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  • Articles: DFG German National Licenses  (224)
  • 1985-1989  (224)
  • 1987  (224)
  • Biochemistry  (133)
  • Physical Chemistry
Source
  • Articles: DFG German National Licenses  (224)
Material
Years
  • 1985-1989  (224)
Year
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Experimental toxicology of formaldehyde (1987)
    Springer
    Journal of cancer research and clinical oncology 113 (1987), S. 305-309 
    Details
    ISSN: 1432-1335
    Keywords: Formaldehyde ; Mutagenicity ; Metabolism ; Biochemistry ; Carcinogenicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Formaldehyde is a reactive chemical which undergoes spontaneous reactions with various cellular constituents. Mutagenicity data may be interpreted on the background of this behavior. Mice are better able to reduce the irritating effect of formaldehyde than rats and to reduce their ventilation rate when formaldehyde acts on the respiratory tract. Subacute exposure of rats to concentrations higher than 2 ppm inhibits mucociliary clearance of the nasal epithelium and leads to progressive histological and ultrastructural lesions at this site. The occurrence of squamous cell carcinomas of the nasal epithelium of rats after 2 years inhalation of 14.3 ppm formaldehyde (CIIT study) is probably the result of chronic and recurrent local toxicity; this is supported by species differences in susceptibility to the tissue damaging and carcinogenic effect of formaldehyde (rat, mouse, hamster). Data on formaldehyde-DNA interaction further support the argument that a direct risk extrapolation from the formaldehyde effects in rats to those expected for man is not possible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00397713
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  • 2
    Electronic Resource
    Electronic Resource
    Myoadenylate deaminase deficiency: absence of correlation with exercise intolerance in 452 muscle biopsies (1987)
    Springer
    Journal of neurology 234 (1987), S. 385-389 
    Details
    ISSN: 1432-1459
    Keywords: Myoadenylate deaminase ; Histochemistry ; Biochemistry ; Neuromuscular diseases ; Exertional myalgia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A histochemical assay was routinely performed of myoadenylate deaminase (MAD) in muscle biopsy specimens. MAD was absent in 13 cases, i.e. 2.9% of the specimens. In 10 cases the deficiency was confirmed biochemically. The diagnoses in the 13 patients were: polyneuropathy (n=5), infantile spinal muscular atrophy (n=3), congenital myopathy with type 2 fibre atrophy, facioscapulohumeral myopathy, polymyositis, myotonic dystrophy and hyperornithinaemia with gyrate atrophy of the retina. In contrast, 35 unrelated patients presenting with exercise-related muscle cramps or pains showed normal histochemical MAD activity. The biopsy specimens in all of these patients were essentially normal and in none of them was the diagnosis of a neuromuscular disease made. The results failed to confirm the association of MAD deficiency with aches, cramps and pains or exertional myalgia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00314082
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  • 3
    Electronic Resource
    Electronic Resource
    Computer enumeration and generation of physical trees (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 549-554 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A computer-oriented method for the enumeration and generation of physical trees is presented. Physical trees depict acyclic chemical structures, but the term physical is used to stress the process by which the structures are produced.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080435
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  • 4
    Electronic Resource
    Electronic Resource
    Announcement (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 562-562 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080437
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  • 5
    Electronic Resource
    Electronic Resource
    Masthead (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987) 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080501
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  • 6
    Electronic Resource
    Electronic Resource
    Towards a quantum chemical software package utilizing transferable fragments as molecular building blocks (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 555-561 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Computer programs have been developed or are under development for the IBM personal computer that enable their users to get information on atomic charges, electrostatic potentials, conformational and other properties of molecular systems containing H, C, N, O, F, Si, P, S, or Cl atoms. The zero-order wavefunction is constructed of strictly localized molecular orbitals with fixed atomic orbital coefficients. The wave function can be refined by optimizing these coefficients, i.e., considering inductive effects via a coupled set of 2 × 2 secular equations within the CNDO/2 approximation. Delocalization and exchange effects are accounted for by expanding the wavefunction on a basis of the aforementioned strictly localized orbitals, instead of conventional atomic orbitals, and solving the corresponding SCF equations. Our method has been applied to the study of large systems. We calculated the electrostatic field of the complex of β-trypsin and basic pancreatic trypsin inhibitor and it has been found that strong field regions more or less coincide with hydration sites. A further potential application of protein electrostatic fields is in NMR spectroscopy. We found a linear correlation between CαH or backbone NH proton chemical shifts and the protein field at the site of the corresponding proton. At last, we propose a simple method to mimic the bulk around atomic clusters modeling crystalline and amorphous silicon. Based on this method we found a linear correlation between atomic net charges and bond angle distortions in silicon clusters with 35 atoms.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080436
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  • 7
    Electronic Resource
    Electronic Resource
    Strain energy minimization study of the mechanism of, and the barrier to, conformational interconversion in five-membered diamine chelate rings (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 651-657 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The method of Lagrangian multipliers is used to constrain torsion angles during molecular mechanics refinement for the purpose of plotting strain energy against a reaction coordinate. A complete two-dimensional analysis of the conformational interconversion from δ- to λ-[Co(ethane-1,2-diamine) (NH3)4]3+ reveals a mechanism in which the transition state geometry has an envelope conformation and an inversion barrier of 15.7 kJ mol-1. Substitution at the carbon atoms, variation of the metal-nitrogen distance, and replacement of the amine ligands with bidentate amines only slightly alters the inversion barrier. Substitution at the nitrogen atoms of the bidentate ligand increases the inversion barrier significantly to 24.6 kJ mol-1 for (N,N,N′,N′-tetramethylethane-1,2-diamine) [(NH3)4]3+.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080510
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  • 8
    Electronic Resource
    Electronic Resource
    Two approaches to the calculation of molecular resonance states: Solution of scattering equations and matrix diagonalizationPresented at the Symposium on Computation and Mathematical Chemistry, Saskatoon, Canada, June 1-4, 1986. (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 683-699 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: We have analyzed two approaches to reproduce the resonance expansion of the scattering matrix appropriate for the calculation of molecular resonance states. The first is based on the resonance theory of Siegert-Humblet-Rosenfeld (SHR) and the second on the Fano-Feshbach formalism. The direct method of calculating the resonance expansion characteristics, devised on the basis of the SHR theory, makes it possible to obtain the energies and partial widths (detailed decay rate constants) of resonances. The Fano-Feshbach formalism, on the other hand, elucidates the resonance state as a concept and facilitates the interpretation of calculation results. The use of computational methods is illustrated by the study of the decay of a model triatomic system and of gas-phase nucleophilic substitution reactions. Used in the latter case is the division of all degrees of freedom of the reacting system into the adiabatic and dynamic ones along with an algorithm of inclusion of the restricted dynamical treatment in the calculation of reaction rate constants.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080514
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  • 9
    Electronic Resource
    Electronic Resource
    The inverse problem of isomer enumerationPresented at the Symposium on Computation and Mathematical Chemistry, Saskatoon, Canada, June 1-4, 1986. (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 700-717 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The present article addresses the problem of identifying the structure of a parent compound through its chemical fingerprints such as the various numbers of isomeric substitution patterns, along the lines of Kekulé when he arrived at his benzene formula. In a pioneering paper (1929), Lunn and Senior laid out the conceptual framework for the permutation group description of substitution isomerism. It remained, however, for Pólya's celebrated contribution (1937) to initiate the actual mathematical realization of their vision. Pólya supplied the tools for solving the isomer enumeration problem: given a (symmetrical) parent compound, enumerate its spectrum of substitution patterns. The converse problem, though ranked the more interesting one by Lunn & Senior, hardly received any mathematical attention. The present article offers a complete and effective solution.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080515
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  • 10
    Electronic Resource
    Electronic Resource
    Molecular graphs as topological objects in spacePresented at the Symposium on Computation and Mathematical Chemistry, Saskatoon, Canada, June 1-4, 1986. (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 718-726 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Stereochemistry deals primarily with distinctions based on rigid geometry, e.g., bond angles and lengths. But some chemical species have molecular graphs (such as knots, catenanes, and nonplanar graphs K5 and K3.3) that reside in space in a topologically nontrivial way. For such molecules there is hope of using topological methods to gain chemical information. Viewing a molecular graph as a topological object in space makes it unrealistically flexible; but if one proves that a certain graph is “topologically chiral” or that two graphs are “topological diastereomers,” then one has ruled out interconversion under any physical conditions for which the molecular graph still makes sense. In this paper, we consider several kinds of topological questions one might ask about graphs in space, methology and results available, and specific topological properties of various molecules.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080516
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  • 11
    Electronic Resource
    Electronic Resource
    Hartree Fock instabilities of sulfur-nitrogen ring systems: S2N2Presented at the Symposium on Computation and Mathematical Chemistry, Saskatoon, Canada, June 1-4, 1986 (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 727-735 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The Hartree-Fock instablities of S2N2 are reported and compared with those of S3N3- and S4N42+. These unsaturated sulfur nitrogen planar rings are π electron rich and although the symmetry adapted HF solutions are singlet stable at the experimental bond lengths they become unstable with only a very modest increase in bond length. The broken symmetry solutions for S2N3, S3N3-, and S4N42+ are of planar C2v type with one of the nitrogens stripped of its π electrons, producing a π hole.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080517
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  • 12
    Electronic Resource
    Electronic Resource
    Masthead (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987) 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080601
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  • 13
    Electronic Resource
    Electronic Resource
    Ab-initioMRD-CI calculations on a C—NO2 decomposition pathway of nitrobenzenePresented at the Symposium on Computation and Mathematical Chemistry, Saskatoon, Canada, June 1-4, 1986. (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 736-743 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: To study molecular decomposition pathways it is necessary to use ab initio multireference determinant-configuration interaction or MCSCF (multiconfiguration SCF) calculations. The MRD-CI (multireference double excitation-configuration interaction technique of Buenker and Peyerimhoff) calculations on the decomposition pathway of nitrobenzene were carried out using all of the occupied molecular orbitals in the region of the bond being dissociated, plus all of the virtual orbitals. An effective CI Hamiltonian was used into which were folded the effects of all of the occupied molecular orbitals from which excitations were not allowed. So far we have investigated the lowest 1A1, 3A1, 1A2, 3A2, 1B1, 3B1, 1B2, 3B2 states and are investigating the higher states. Our results show a wealth of structure in the potential energy surfaces for the various electronic states of nitrobenzene as a function of distance. A number of the states are predissociative and change dominant configuration one or more times along these potential energy surfaces.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080518
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  • 14
    Electronic Resource
    Electronic Resource
    Hamiltonian dynamics of chemical reactions. Consecutive first-order reactions and reactions possessing one autocatalytic intermediatePresented at the Symposium on Computation and Mathematical Chemistry, Saskatoon, Canada, June 1-4, 1986. (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 744-751 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A recently proposed Hamiltonian approach to phenomenological chemical kinetics [T. Georgian and G.L. Findley, Int. J. Quantum Chem., Quantum Biol. Symp. 10, 331 (1983); T. Georgian, J.M. Halpin, and G.L. Findley, Int. J. Quantum Chem., Quantum Biol. Symp. 11, 347 (1984)] is applied to all consecutive first-order, single-step reactions, and to all reactions possessing one autocatalytic intermediate. The reaction Hamiltonians presented are shown to be consistent with the phenomenological rate equations and the relationship between reaction form and the form of the reaction potential is discussed. In particular, we show: (1) that the interaction between consecutive reactions manifests itself as a coupling term in the reaction potential, a term which may be eliminated via transition to “normal reaction coordinates” for the chemical system; and (2) that coupled sets of autocatalytic reactions give rise to coupling terms in the reaction Hamiltonian which are characteristic of the reaction mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080519
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  • 15
    Electronic Resource
    Electronic Resource
    Column design. 3. Theoretical studies of a chiral stationary phase used in column chromatography (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 753-760 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Conformational features of a chiral stationary phase used in column chromatography are discussed. The syn forms invoked in chiral recognition models are consistent with MNDO and MM2 calculations. It is speculated that the inherent flexibility of the syn form makes these phases effective templates for analyte binding.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080602
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  • 16
    Electronic Resource
    Electronic Resource
    Ab initio study of the He(1S)-Li2(X̃, 1∑g+) interaction by the SCF and MP2 methods (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 761-771 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Ab initio electronic structure calculations have been carried out for the He(1S)-Li2 (X̃, 1∑g+) interaction both by the single-configuration SCF and correlated second-order MP2 methods using an extended basis set. From these calculations, an estimate of the isotropic (V0) and first two anisotropic (V2 and V4) terms of the He-Li2 potential surface has been obtained. An assessment of the leading induced-dipole-induced-dipole dispersion energy is presented from the MP2 energies. Where possible, a comparison is made with previous unpublished ab initio calculations by Staemmler and Stahl using the CEPA method.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080603
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  • 17
    Electronic Resource
    Electronic Resource
    CNDO Force constants for glucose (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 772-777 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Force constants for both anomers of glucose are evaluated using CNDO/Force method.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080604
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  • 18
    Electronic Resource
    Electronic Resource
    Electrostatic interaction of a solute with a continuum. Improved description of the cavity and of the surface cavity bound charge distribution. (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 778-787 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Algorithms for a finer description of cavities in continuous media and for a more efficient selection of sampling points on the cavity surface are described. Applications to the evaluation of solute surface and volume and to the calculation of the solute-solvent electrostatic interaction energy, as well as of the cavitation energy are shown as examples.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080605
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  • 19
    Electronic Resource
    Electronic Resource
    A study of basis set effects on structures and electronic structures of phosphine oxide and fluorophosphine oxide (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 788-793 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A variety of basis sets have been used for geometric and electronic structure studies. Electronic effects were measured using integrated spatial electron populations (ISEP). The two largest basis sets used, 6-31G* and DZ+P, give significantly different results. Use of two d-orbital sets (6-31G*[dd]) or decontraction of the 2sp shell on phosphorus has little further effect. d-Orbitals on oxygen are required for consistent electronic structure results, and d-orbitals on fluorine have a small but significant effect. Use of diffuse functions, required for anions, is not recommended with small basis sets on neutral molecules. Large negative charges (≈-1.5) on oxygen are given by all of the larger basis sets by the ISEP procedure and indicate that the PO bond in these compounds is largely semi-polar. The best simple symbolic representation of phosphine oxide is H3P+—0-, rather than H3P=0.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080606
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  • 20
    Electronic Resource
    Electronic Resource
    Basis set and correlation effects on computed positive ion hydrogen bond energies of the complexes AHn · AHn + 1+1: AHn = NH3, OH2, and FH (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 810-815 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Basis set expansion and correlation effects on computed hydrogen bond energies of the positive ion complexes AHn · AHn + 1+1, for AHn = NH3, OH2 and FH, have been evaluated. The addition of diffuse functions on nonhydrogen atoms is the single most important enhancement of split-valence plus polarization basis sets for computing hydrogen bond energies. Basis set enhancement effects appear to be additive in these systems. The correlation energy contribution to the stabilization energies of these complexes is significant, with the second order term being the largest term and having a stabilizing effect. The third order term is smaller and of opposite sign, while the fourth order term is smaller yet and stabilizing. As a result, computed MP4 stabilization energies are bracketed by the MP2 and MP3 energies. The overall effect of basis set enhancement is to decrease hydrogen bond energies, whereas the addition of electron correlation increases stabilization energies.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080609
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  • 21
    Electronic Resource
    Electronic Resource
    A powerful truncated Newton method for potential energy minimizationThis work would not have been possible without the expert contibutions of Charles Peskin and Suse Broyde. (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 1025-1039 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: With advances in computer architecture and software, Newton methods are becoming not only feasible for large-scale nonlinear optimization problems, but also reliable, fast and efficient. Truncated Newton methods, in particular, are emerging as a versatile subclass. In this article we present a truncated Newton algorithm specifically developed for potential energy minimization. The method is globally convergent with local quadratic convergence. Its key ingredients are: (1) approximation of the Newton direction far away from local minima, (2) solution of the Newton equation iteratively by the linear Conjugate Gradient method, and (3) preconditioning of the Newton equation by the analytic second-derivative components of the “local” chemical interactions: bond length, bond angle and torsional potentials. Relaxation of the required accuracy of the Newton search direction diverts the minimization search away from regions where the function is nonconvex and towards physically interesting regions. The preconditioning strategy significantly accelerates the iterative solution for the Newton search direction, and therefore reduces the computation time for each iteration. With algorithmic variations, the truncated Newton method can be formulated so that storage and computational requirements are comparable to those of the nonlinear Conjugate Gradient method. As the convergence rate of nonlinear Conjugate Gradient methods is linear and performance less predictable, the application of the truncated Newton code to potential energy functions is promising.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080711
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  • 22
    Electronic Resource
    Electronic Resource
    An efficient newton-like method for molecular mechanics energy minimization of large molecules (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 1016-1024 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Techniques from numerical analysis and crystallographic refinement have been combined to produce a variant of the Truncated Newton nonlinear optimization procedure. The new algorithm shows particular promise for potential energy minimization of large molecular systems. Usual implementations of Newton's method require storage space proportional to the number of atoms squared (i.e., O(N2)) and computer time of O(N3). Our suggested implementation of the Truncated Newton technique requires storage of less than O(N1.5) and CPU time of less than O(N2) for structures containing several hundred to a few thousand atoms. The algorithm exhibits quadratic convergence near the minimum and is also very tolerant of poor initial structures. A comparison with existing optimization procedures is detailed for cyclohexane, arachidonic acid, and the small protein crambin. In particular, a structure for crambin (662 atoms) has been refined to an RMS gradient of 3.6 × 10-6 kcal/mol/Å per atom on the MM2 potential energy surface. Several suggestions are made which may lead to further improvement of the new method.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080710
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  • 23
    Electronic Resource
    Electronic Resource
    On the out-of-plane deformation of aromatic rings, and its representation by molecular mechanics (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 1051-1056 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: It has been found that the previous MM2 (or MMP2) description of out-of-plane deformation of aromatic rings sometimes yields distortions which are much too large. As a result, rotational barriers involving distortions of such rings may be calculated to have values which are too low. Examples are collected and discussed. An alternative formulation, which appears to significantly reduce the calculational error, is presented.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540080713
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    Electronic Resource
    Scientific and engineering applications with personal computer, r. annino and r.d. driver. wiley, new york, 1986, $45.00, 577 pp. (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 1066-1067 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080715
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    Electronic Resource
    Electronic Resource
    Molecular orbital calculations on solvents and other small molecules: Correlation between electronic and molecular properties ν, αMOL, π*, and β. (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 1084-1089 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Molecular orbital calculation by the MINDO/3 method are reported for 50 compounds used as solvents in chemical reactions. Relationships between various parameters of electronic structure and molecular properties such as dipole moment, polarizability and Taft solvent parameters are presented. Comparison between experimental values of π* and calculated values is given.
    Additional Material: 5 Tab.
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    URL: http://dx.doi.org/10.1002/jcc.540080803
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    Electronic Resource
    Systematic drug receptor mapping: A new approach to the analysis of conformational energy calculations of flexible molecules with application to dopaminergic and adrenergic agonists (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 1075-1083 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The computer program PRODIS is used to find low energy conformations of flexible molecules by searching the potential energy surface(s) of one or more torsion angles via rigid rotation. The n-dimensional grid of energy versus torsion angles is then converted to a Boltzman probability distribution, with the probability being represented not as a function of torsion angle, but rather a distance between two atoms. These atoms are chosen by comparison with a known, active analogue in which certain atoms have previously been determined as requirements for drug activity. PRODIS produces a list of low energy conformations, their corresponding interatomic distances and the Boltzman probability for each distance ±0.125, as well as the total probability for each conformation. The user also specifies a target interatomic distance and range (usually derived from a more rigid analogue) for which PRODIS lists all conformations and their Boltzman probability that meet this distance.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540080802
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  • 27
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    Electronic Resource
    On the use of constraints in molecular mechanics. II. The Lagrange multiplier method and non-full-matrix Newton-Raphson minimization (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 1099-1103 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: It is shown how the Lagrange Multiplier method for constrained minimization can be implemented in a molecular mechanics program using the common approximations to the full-matrix Newton-Raphson minimization. The method reduces the number of cycles to achieve convergence, and also stabilizes the refinement process. Increases in computer memory requirements are small. As an application, the conformational surface of cycloheptane is calculated.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540080805
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    Electronic Resource
    Electronic Resource
    Molecular mechanics study of myelin basic protein (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 1104-1108 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Myelin basic protein (MBP) is the major extrinsic protein of the myelin sheath in the central nervous system. We have examined the predicted structure of segments of MBP using the molecular mechanics program ECEPP83 developed by Scheraga and coworkers as modified by Chuman, Momany, and Schafer. We have focused upon segments containing the Pro-Pro-Pro sequence (residues 100-102), which have been predicted from standard algorithms to exist in a hairpin loop connecting anti-parallel beta-strands. Both the shorter (98-105, 99-105, and 100-105) and longer segments (87-109, 87-118, and 87-120) have been examined. These results indicate potential for a chain reversal in this region. The shorter segments have been studied by others using NMR techniques and the results are compared.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540080806
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  • 29
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    An evaluation of the performance of diffuse function-augmented basis sets for second row elements, Na-ClPart IV of a series on Efficient Diffuse Function-Augmented Basis Sets for Anion Calculation. (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 1109-1116 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The energetic effects of the addition of diffuse functions to molecules with second-row elements are much less dramatic than those for their first-row counterparts. Although diffuse functions on second-row elements have little effect on the geometries and vibrational frequencies of neutral molecules, significant changes are found for anions. While the largest basis set, 6-31 + G*, generally performs best, the results at 3-21 + G* are comparable, and this basis can be recommended for practical applications.
    Additional Material: 10 Tab.
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  • 30
    Electronic Resource
    Electronic Resource
    Semi-empirical calculations of molecular trajectories: Method and applications to some simple molecular systems (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 1117-1123 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The MNDO Hamiltonian as incorporated within MOPAC has been utilized to predict dynamics for some simple reactions. In one option, the intrinsic reaction coordinate has been followed along the path of steepest descent from the transition state backward to reactants and forward to products. In a second option, dynamics of isolated molecular systems have been calculated. In each case, the potential surface (as predicted by the MNDO Hamiltonian) is calculated in situ as the atomic trajectories are calculated from Newton's Laws of Motion. Several specific examples are given and discussed.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540080808
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    Electronic Resource
    Cooperative effects in extended hydrogen bonded systems involving O—H groups. Ab initio studies of the cyclic S4 water tetramer (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 1090-1098 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The additional energy stabilization due to cooperative effects was calculated in extended hydrogen bonded systems O—H⃛O—H⃛O—H with unidirectional (homodromic) orientation of the O—H groups. Ab initio restricted Hartree Fock, MP2 and MP3 calculations with geometry optimization and BSSE correction have been performed using the GAUSSIAN 83 program package for the ground states of the linear water dimer with Cs symmetry and the cyclic water tetramer with S4 symmetry. The latter represents the smallest possible, experimentally observed cooperative structure. A new definition for a cooperativity parameter is proposed. The definition is based on the two-body, non-neighbour interaction energy, plus three- and four-body contributions, including one-body deformation terms in relation to the total interaction energy of the water tetramer. The advantage of this definition is its independence of the reference system, which is necessary in complicated molecular systems with an undefined number of hydrogen bonds, such as disordered or flip-flop systems. According to this definition the energy gain based on cooperativity in the S4 water tetramer is 29% with the MP3/6-31G** approximation, (30% with HF/4-31G* and 46% with HF/3-21G). The largest contribution of 18% is due to the three-body term on the MP3/6-31G** level, followed by the two-body, non-neighbour term with 11%. The four-body term and the deformation term are in the order of 1% and cancel each other because they have opposite sign.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540080804
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    Electronic Resource
    Nonbonded interactions. 1. Anisotropic hydrogen-hydrogen interactions (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 1124-1130 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The hydrogen-hydrogen nonbonded potential which may be derived from the calculated interactions between hydrogen molecules has been obtained. The best three-parameter Buckingham function gave an RMS error of 0.18 kcal/mol in fitting Price and Stone's ab initio data for 130 pairs of hydrogen molecules, which may be compared with an RMS error of 0.74 kcal/mol using the parameters in the MM2 force field. Burton's basis set is also considered. A better fit to these data requires that the angular relationship between the bonds be included. The data for hydrogen as well as experimental data for chlorine show that these atoms appear “larger” normal to the bond axis than along the axis, and this is probably also the case for other atoms. When simple angular terms are added it is possible to fit the Price and Stone data set with an RMS error of less than 0.06 kcal/mol. The preferred function was: V = [a0 + a1(sin θ1 + sin θ2)4 + a2r]e-3r - [c0 + c1(1 + sinθ1sinθ2)]/r5. Deficiencies in the current ab initio data are discussed.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540080809
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    An analysis of the structural and energetic properties of deoxyribose by potential energy methods (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 1199-1224 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: We discuss the three fundamental issues of a computational approach in structure prediction by potential energy minimization, and analyze them for the nucleic acid component deoxyribose. Predicting the conformation of deoxyribose is important not only because of the molecule's central conformational role in the nucleotide backbone, but also because energetic and geometric discrepancies from experimental data have exposed some underlying uncertainties in potential energy calculations. The three fundamental issues examined here are: (i) choice of coordinate system to represent the molecular conformation; (ii) construction of the potential energy function; and (iii) choice of the minimization technique. For our study, we use the following combination. First, the molecular conformation is represented in cartesian coordinate space with the full set of degrees of freedom. This provides an opportunity for comparison with the pseudorotation approximation. Second, the potential energy function is constructed so that all the interactions other than the nonbonded terms are represented by polynomials of the coordinate variables. Third, two powerful Newton methods that are globally and quadratically convergent are implemented: Gill and Murray's Modified Newton method and a Truncated Newton method, specifically developed for potential energy minimization. These strategies have produced the two experimentally-observed structures of deoxyribose with geometric data (bond angles and dihedral angles) in very good agreement with experiment. More generally, the application of these modeling and minimization techniques to potential energy investigations is promising. The use of cartesian variables and polynomial representation of bond length, bond angle and torsional potentials promotes efficient second-derivative computation and, hence, application of Newton methods. The truncated Newton, in particular, is ideally suited for potential energy minimization not only because the storage and computational requirements of Newton methods are made manageable, but also because it contains an important algorithmic adaptive feature: the minimization search is diverted from regions where the function is nonconvex and is directed quickly toward physically interesting regions.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540080817
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    Electronic Resource
    A modeling study of the oxidation of propionaldehyde in the negative temperature coefficient regime (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 457-486 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A chemical kinetic reaction mechanism has been developed which describes the oxidation of propanal within the temperature range 400-700 K. This mechanism has been tested against data obtained by four experimental groups over a wide range of initial conditions. The induction period and the absolute rate of propanal consumption are predicted to within a factor of 2 for initial densities of oxygen and propanal ranging over factors of 400. The existence and location of the negative temperature coefficient in the consumption of propanal are also simulated properly. The yields of all major and most minor products are predicted to within a factor of 2 for the wide variety of initial conditions tested. Sensitivity analyses were carried out at 553 and 713 K to identify the reactions primarily responsible for controlling the rate of propanal consumption and the distribution of products.
    Additional Material: 11 Ill.
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    URL: http://dx.doi.org/10.1002/kin.550190506
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    Electronic Resource
    Kinetic study of the reaction of IO with CH3SCH3 (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 503-512 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction IO + CH3SCH3 → products (3) was studied at room temperature and near 1 Torr pressure of He, using the discharge flow mass spectrometric technique. The rate constant was found to be k3 = (1.5 ± 0.5) × 10-11 cm3 molecule-1 s-1. CH3S(O)CH3 was detected as a product suggesting the following channel: IO + CH3SCH3 → CH3S(O)CH3 + I. The rate constant of the reaction IO + IO → products (1) was also measured: k1 = (3 ± 0.5) × 10-11 at 298 K and 1 Torr pressure. The atmospheric implication of reaction (3) is discussed. The results indicate that this reaction could be a potential important sink of CH3SCH3 in marine atmosphere.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/kin.550190603
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    Kinetics of the acyl migration in some adducts of acyl-1, 4-benzoquinones: Part I (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 49-60 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rates of migration of acetyl, propionyl, isobutyryl, and benzoyl substituent in Diels-Alder adducts of acyl-1, 4-benzoquinones, (enediones), (I), to form the corresponding 2-acyl hydroquinones, (II), in 50% (v/v) ethanolic pyridine have been studied in detail. Rate dependence on pyridine concentration has been established and maximum rate was found at pyridine a volume percent of 25 in an ethanolic reaction mixture. The study indicated first-order dependence on reactants and fractional dependence on pyridine concentration. The effect of substituents of the acyl group on the rate showed that electronic factors play an important role on the stability of the transition state. A plausible mechanism, which is consistent with the results has been postulated and suitable rate law in consonance with the postulated mechanism have been derived.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/kin.550190106
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    Electronic Resource
    Thermal reactions of acetonitrile at high temperatures. Pyrolysis behind reflected shocks (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 61-79 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal decomposition of acetonitrile was studied behind reflected shocks in a single pulse shock tube over the temperature range 1350-1950 K at overall densities of approximately 3 × 10-5 mol/cc. Methane and hydrogen cyanide are the major reaction products. They are formed by an attack of H and CH3 radicals on acetonitrile. The initiation step of the pyrolysis is the self dissociation of acetonitrile: for which the following rate constant was obtained: k1 = 6.17 × 1015exp(-96.6 × 103/RT)sec-1. Where R is given in units of cal/K mol. Additional reaction products which appear in the pyrolysis are: C2H2, C2H4, CH2=CHCN, CH≡CHCN, C2H5CN, C2N2, and C4H2. Acetylene is formed from methane pyrolysis and becomes a major reaction product at high temperatures. Acrilonitrile and cyanoacetylene are secondary products originating from the CH2CN radical. Rate parameters for the formation of the reaction products are given.
    Additional Material: 13 Ill.
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    URL: http://dx.doi.org/10.1002/kin.550190107
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    Electronic Resource
    The reaction of acetylperoxy radicals with NO2 (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 115-128 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Acetylperoxy radicals were produced by the flash photolysis of chlorine in the presence of acetaldehyde and oxygen. By adding various concentrations of nitrogen dioxide, the rate constant for the reaction producing PAN was measured to be k4 (153 Torr) = (2.29 ± 0.05) × 109 L/mol s.The effect of pressure has been studied over the range 76-612 Torr and the data fitted to a fall-off curve with k4∘ = 1.85 × 1013 L2/mol2 s. and k4x = 3.67 × 109 L/mol s. With a calculated value of the dissociation constant, k-4∘ = 268 L/mol s and of the equilibrium constant, K4 = 1.04 × 1012 L/mol, the expected strong collision value for k4∘ is 2.79 × 1014 L2/mol2 s.The ultraviolet absorption spectrum of PAN has been characterized in the range 205-260 nm.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/kin.550190204
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    Structure-reactivity relationships and the rate-determining step in the reactions of methyl salicylate with primary amines (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 415-434 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The aqueous cleavage of methyl salicylate has been studied in the buffer solutions of various primary mono- and di-amines as well as secondary amines at 30°C. Both ionized (MS-) and nonionized (MSH) methyl salicylate are reactive toward primary mono- and di-amines. The second-order rate constants for the reactions of MS- with primary mono- and di-amines of pKa 〉 9.4 exhibit Bronsted plot of slope (βnuc) of 0.82. This high value of βnuc is attributed to an intramolecular proton transfer in a thermodynamically unfavorable direction in the rate-determining step in a stepwise process for the formation of monoanionic tetrahedral intermediate. However, a concerted process for the formation of a monoanionic tetrahedral intermediate in the reactions of MS- with amine nucleophiles wherein expulsion of leaving group is a rate-determining step is not completely ruled out. The α-effect nitrogen nucleophiles hydroxylamine and hydrazine reveal, respectively, ca. 104- and 103-fold higher reactivity compared to other amine nucleophiles of comparable basicity. The value of βnuc of 1.03 obtained for the reactions of primary monoamines with MSH is ascribed to the expulsion of leaving group as the rate-determining step. The significantly lower value of βnuc of 0.60 obtained in the reactions of MSH with both monoprotonated and unprotonated diamines is explained in terms of possible occurrence of intramolecular general acid-base catalysis. Intramolecular general base catalysis is responsible for the enhanced nucleophilic reactivity of primary amines toward MS-. Dimethylamine, piperidine, morpholine, and piperazine have no detectable nucleophilic reactivity toward MS-.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/kin.550190504
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    Kinetics of the gas-phase thermal elimination of N-alkyl-pyrazoles (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 571-578 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetic study of the gas-phase thermal elimination reactions of N-ethyl-3,5 dimethyl-pyrazole (I), N-ethyl-pyrazole (II), N-sec-butyl-pyrazole (III), and N-tert-butyl-pyrazole (IV) using a flow system is reported. After obtaining activation parameters for I we carried out competitive reactions with II, III and IV using I as internal standard to obtain their Ea. The values of Δ(ΔHfo) calculated for II, III and IV agree with the little differences in Ea experimentally found.
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    URL: http://dx.doi.org/10.1002/kin.550190608
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    The kinetics of oxiranes addition to bis/2-hydroxyalkyl/disulfides and bis/2-hydroxyalkyl/sulfides in the presence of N,N-dimethylcyclohexylaminePart IV of the series: Organic Sulfur Compounds, Part III: A. Sokołowski and B. Burczyk, Angew. Makromol. Chem., 129, 143 (1985). (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 615-626 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rate constants for the reaction of oxiranes with bis/2-hydroxyalkyl/disulfides, bis/2-Hydroxyalkyl/sulfides, and 1,6-Hexanediol in the presence of N,N-dimethylcyclohexylamine were studied at the temperature range of 50-90°C. A mechanism of these reactions has been proposed and its kinetic equation has been presented.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/kin.550190704
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    Electronic Resource
    Exchange reactions in selectively excited Br2(B3Πou+) (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 639-647 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Laser-controlled bimolecular isotopic exchange reactions in bromine leading to alterations in natural isotopic abundance ratios have been directly observed using laser-modulated molecular beams and mass analysis. Several instances of selective excitation and subsequent rapid isotope exchange are observed within the 7 GHz gain curve of the exciting 514.5 nm line of an argon-ion laser. These exchange processes are attributed to the direct photochemical participation of excited molecular states in the B3Πou+ system of Br2.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/kin.550190706
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    The decomposition kinetics of disilane and the heat of formation of silylene (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 715-724 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The static system decomposition kinetics of disilane (\documentclass{article}\pagestyle{empty}\begin{document}${\rm Si}_{\rm 2} {\rm H}_{\rm 6} \mathop {\longrightarrow}\limits^1 {\rm SiH}_{\rm 2} + {\rm SiH}_{\rm 4}$\end{document}, 538-587 K and 10-500 Torr), are reported. Reaction rate constants are weakly pressure dependent, and best fits of the data are realized with RRKM fall-off calculations using logA1,∞ = 15.75 and E1,∞ = 52,200 cal. These parameters yield AHf0(SiH2)298 = (63.5 - Eb, c) kcal mol,-1 where Eb, c is the activation energy for the back reaction at 550 K, M = 1 std state. Five other silylene heat-of-formation values (ranging from 63.9 - Eb, c to 66.0 - Eb, c kcal mol-1) are deduced from the reported decomposition kinetics of trisilane and methyldisilane, and from the reported absolute and relative rate constants for silylene insertions into H2 and SiH4. Assuming Eb, c = 0, an average value of ΔHf0(SiH2) = 64.3 ± 0.3 kcal mol-1 is obtained. Also, a recalculation of the activation energy for silylene insertion into H2, based in part on the new disilane decomposition Arrhenius parameters, gives (0.6 + Eb, c) kcal mol-1, in good agreement with theoretical calculations.
    Additional Material: 4 Tab.
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    The maximally inhibited gas phase pyrolysis kinetics of primary alkyl bromides. The taft correlation of alkyl substituents (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 781-785 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/kin.550190810
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  • 45
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    Electronic Resource
    Masthead (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987) 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550190901
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  • 46
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    Absolute rate constants for the reaction of Br atoms with i-C4H10 (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 829-839 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/kin.550190904
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  • 47
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    Kinetic study of the iodine-catalyzed alcoholysis of Butoxytriethylsilane: n-butoxy group - s-butoxy group exchange reaction (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 841-849 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to appreciate the excellent catalytic effect of iodine on the alcoholyses of alkoxysilanes more precisely, the rates of the reaction, Et3SiOBun + BusOH ⇌ Et3SiOBus + BunOH, were determined at various iodine concentrations.Both forward and reverse reactions are first order with respect to butoxysilane and to butanol, and pseudo first-order rate constants were measured at 40°, 30°, and 20°C on reaction mixtures containing both butanols in excess by means of gas-liquid chromatography. The observed rate constants as a function of iodine concentration gave linear relationships, and from these data the catalytic coefficients of iodine were evaluated: \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {k_{2_{{\rm I}_2 } } = 7.4 \times 10^7 \exp (- 55.7 \times 10^3 /RT)} & {({\rm forward\, reaction})} \\ \end{array} $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {k_{{ -2} _{{\rm I} _2 } } = 9.7 \times 10^7 \exp (- 54.3 \times 10^3 /RT)} & {({\rm reverse\, reaction})} \\ \end{array} $$\end{document} The enthalpies and the entropies of activation were estimated to be 53.2 kJ mol-1, -103 J K-1 mol-1 (forward, 30°C) and 51.8 kJ mol-1, minus;100 J K-1 mol-1 (reverse, 30°C).
    Additional Material: 2 Ill.
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  • 48
    Electronic Resource
    Electronic Resource
    High-temperature collisional energy transfer in highly vibrationally excited molecules II: Isotope effects in isopropyl bromide systems (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 851-867 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Values for 〈ΔEdown〉, the average downward energy transferred from the reactant to the bath gas upon collision, have been obtained for highly vibrationally excited undeuterated and per-deuterated isopropyl bromide with the bath gases Ne, Xe, C2H4, and C2D4, at ca. 870 K. The technique of pressure-dependent very low-pressure pyrolysis (VLPP) was used to obtain the data. For C3H7Br, the 〈ΔEdown〉 values (cm-1) are 490 (Ne), 540 (Xe), 820 (C2H4), and 740 (C2D4), and for C3D7Br, 440 (Ne), 570 (Xe), 730 (C2H4), and 810 (C2D4). The uncertainties in these values are ca. ±10%. The 〈ΔEdown〉 values for the inert bath gases Ne and Xe show excellent agreement with the theoretical predictions of the semi-empirical biased random walk model for monatomic/substrate collisional energy exchange [J. Chem. Phys., 80, 5501 (1984)]. The relative effects of deuteration of the reactant molecule on 〈ΔEdown〉 also compare favorably with the predictions of this theoretical model. Extrapolated high-pressure rate coefficients (s-1) for the thermal decomposition of reactant are 1013.6±0.3 exp(-200 ± 8 kJ mol-1/RT) for C3H7Br and 1013.9±0.3 exp(-207 ± 8 kJ mol±1/RT) for C3D7Br, which are consistent with previous studies and the expected isotope effect.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/kin.550190906
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  • 49
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    Isomerization of n-hexyl and s-octyl radicals by 1,5 and 1,4 intramolecular hydrogen atom transfer reactions (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 895-921 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: n-Hexyl and s-octyl radical isomerizations by intramolecular hydrogen atom shift have been studied in the presence of high methyl radical concentration where isomerized alkyl radicals reacted predominantly by combination and disproportionation reactions with methyl radicals.By assuming the rate coefficient of 1-hexyl radical recombination to be equal to that of ethyl self-combination, the rate coefficient of log(k1/s-1) = (9.5 ± 0.3) - (11.6 ± 0.3) kcal mol-1/RT ln 10 has been derived for the 6sp isomerization of n-hexyl radicals, 1-hexyl → 2-hexyl (1).Investigation of s-octyl radical isomerization was complicated by fast interconversion between 3-octyl, 2-octyl, and 4-octyl radicals. Use of the methyl trapping technique and systematic variation of methyl radical concentration made possible the determination of log(k2/s-1) = (9.4 ± 0.7) - (11.2 ± 1.0) kcal mol-1/RT ln 10 for the 6ss isomerization of 3-octyl and the estimation of log(k3/s-1) = 10.5-17 kcal mol-1/RT ln 10 for the 5ss isomerization of 2-octyl radicals, where 3-octyl → 2-octyl (2), and 2-octyl → 4-octyl (3).
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/kin.550191003
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  • 50
    Electronic Resource
    Electronic Resource
    Masthead (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987) 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550190201
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  • 51
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    Characterization of solid solutions composed of oxides of Cu, Zn, and Cr for methanol synthesis (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 105-113 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Solid solutions of Cu2O alone and Cu2O with ZnO or Cr2O3 in ZnO · Cr2O3 as well as solid solutions of ZnO in Cu2O · Cr2O3 have activities and selectivities for methanol synthesis comparable to solid solutions of Cu2O in ZnO. Addition of a secondary phase to these solid solutions limits the grain growth and produces higher surface areas.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/kin.550190203
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  • 52
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    The mechanism and rate parameters for the pyrolysis of n-hexane in the range 723-823 K (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 81-103 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The pyrolysis of n-hexane has been investigated in the ranges 723-823 K and 10-100 Torr at up to 3% decomposition. The reaction is homogeneous and free from the self-inhibition by olefin products observed for several other alkanes. The products of the reaction are hydrogen, methane, ethane, ethene, propene, but-1-ene, and pent-1-ene, with smaller amounts of propane. It is shown that the results are in quantitative agreement with a conventional Rice-Herzfeld chain mechanism terminated by the combination and disproportionation of ethyl radicals, but with the mechanism extended so as to include the unimolecular isomerizations via a six-membered cyclic transition state between 1-hexyl and 2-hexyl (1-methylpentyl) radicals.The overall rate constant of initiation is estimated to be given by \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm log(}k_1 /{\rm s}^{ - {\rm 1}}) = 17.77 - (83.8\,{\rm kcal\, mol}^{ - {\rm 1}})/(2.3{\rm }RT) $$\end{document} The rate constant for the reaction is given by \documentclass{article}\pagestyle{empty}\begin{document}$$ \log (k_9 /{\rm cm}^{\rm 3}\, {\rm mol}^{ - 1} {\rm s}^{ - 1}) = 13.30 - (17.9{\rm \, kcal\, mol}^{ - 1})/(2.3{\rm }\,RT) $$\end{document} which when combined with published data gives an Arrhenius plot curved upwards at low values of 1/T as has been observed for several other hydrogen abstraction reactions of methyl and of ethyl. Estimates are made of rate constants and ratios of rate constants for several reactions of the free radicals involved in the reaction. It is suggested that the minor product propane arises mainly from a hydrogen abstraction by 1-propyl from hexane with a contribution from a minor termination process involving ethyl and methyl.
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    URL: http://dx.doi.org/10.1002/kin.550190202
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  • 53
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    A critical review of the chemical kinetics of SF4, SF5, and S2F10 in the gas phase (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 129-142 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The gas phase chemical kinetics of SF4, SF5, and S2F10 are reviewed with particular emphasis on relevance to the general problem of the dielectric breakdown of SF6. Specific reaction systems treated are SF4 + F2, SF5 + SF5, and the pyrolysis of S2F10. Computer modeling calculations were carried out to arrive at the best estimates of rate parameters. Based on the results of these calculations, sets of recommended rate parameters are provided. The major discrepancies and problems in establishing the kinetic data base are described. Thermochemical consequences of different model calculations are given.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/kin.550190205
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  • 54
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    The kinetics and mechanism of alkaline hydrolysis of N-substituted phthalimides (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 143-153 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The aqueous cleavage of N-(2-bromoethyl)phthalimide (NBEPH), N-(3-bromopropyl)phthalimide (NBPPH), and N-carbethoxyphthalimide (NCPH) have been studied within the [ŌH] range of 5 × 10-4 M to 2 × 10-3 M, pH range of 8.82 to 10.62 and 8.06 to 8.66, respectively. The observed pseudo-first-order rate constants, kobs, reveal a linear relationship with [ŌH] with essentially zero intercept. The alkaline hydrolysis of N-(hydroxymethyl)phthalimide (NHMPH) has been studied within the [ŌH] range of 5.64 × 10-6 M to 2.0 M. The [OH]-rate profile reveals that both ionized and nonionized NHMPH are reactive toward ŌH. The second-order rate constant, kOH, for the reaction of ŌH with non-ionized NHMPH is ca. 104 times larger than that with ionized NHMPH. The values of kOH obtained for NBEPH, NBPPH, NCPH, and nonionized NHMPH show a reasonable linear relationship with Taft substituent constants, and the slope (ρ*) of the plot is 1.01 ± 0.10. The low value of ρ* of 1.01 is attributed to nucleophilic attack as the rate-limiting. The kOH value for ionized NHMPH reveals nearly 103-fold negative deviation from the linear Taft plot.
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    URL: http://dx.doi.org/10.1002/kin.550190206
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  • 55
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    Electronic Resource
    Masthead (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987) 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550190301
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  • 56
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    Kinetics and mechanism of electron transfer from phenolate anion to hexacyanoferrate (III) in aqueous alkaline media (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 155-170 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A kinetic reinvestigation of the title redox system in aqueous alkaline media at 35°C and an ionic strength of 0.5 mol dm-3 shows that the reaction follows a pseudosecond-order Fe(CN)63- disappearance. While varying [phenol]0 and [OH-] exhibit a linear influence on the pseudo-second-order rate constant, varying[Fe(CN)63-]0 and [Fe(CN)64-]0, initially taken, have a complicated inhibitory effect on the same. The major phenoloxidation products isolated under a chosen condition are 2,2′- and 4,4′- dihydroxydiphenyl. Results are interpreted in terms of a probable mechanism which envisages a reversible formation, by the first one-electron transfer, of a reactive phenoxy radical (PhO·) which on the second one-electron transfer forms a less reactive ion-pair intermediate (stabilized by the Fe(CN)64- produced) to decompose rate-determiningly to phenoxonium cation (PhO+) and Fe(CN)64-, the product-formation steps being very rapid and kinetically indistinguishable.
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    URL: http://dx.doi.org/10.1002/kin.550190207
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  • 57
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    On the errors of Arrhenius parameters and estimated rate constant values (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 171-181 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A detailed statistical study is presented, based on simulated experimental data, on the estimation of activation parameters using the Arrhenius equation: k = A exp(B/T). The close correlation of the two parameters is shown, which requires the computation of the covariance matrix for the representation of uncertainties. This matrix facilitates the correct estimation of the confidence interval for interpolated (or extrapolated) values of rate coefficients. It is proposed that the full correlation matrix should be published in any article dealing with the determination of Arrhenius parameters.The importance of correct weighting is emphasized. Nonlinear fitting to the Arrhenius equation can be carried out without weighting only in case the (absolute) error of rate coefficient is independent of the temperature. Simulated experiments show that noncorrect weighting shifts the average values of fitted parameters and increases the variance of the parameters as well.With respect to the modified Arrhenius equation: k = A · Tn exp(B/T), statistical analysis shows that the physically meaningful estimation of all three parameters is impossible. Nonlinear fitting of three parameters is suggested for interpolation (and extrapolation) of rate coefficients, whereas in case of activation parameter estimation, the fixing of “n” on the basis of theoretical considerations is advised followed by the estimation of the remaining two parameters.
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    URL: http://dx.doi.org/10.1002/kin.550190302
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  • 58
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    Neighboring group participation in the pyrolysis kinetics of 4-chloro-1-butanol in the gas phase (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 183-189 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The pyrolysis of 4-chloro-1-butanol has been studied in a static system, seasoned with allyl bromide, and in the presence of the free radical suppressor toluene. The working temperature and pressure ranges were 400-450°C and 43-164 Torr, respectively. The reaction is homogeneous, unimolecular, and follows a first-order rate law. The temperature dependence of the rate coefficients is given by the following Arrhenius equation: log k1(s-1) = (13.34 ± 0.50) - (221.1 ± 6.7) kJ mol-1 (2.303RT)-1. The products tetrahydrofuran, formaldehyde, and propene, arise by the participation of the neighboring OH group in 4-chloro-1-butanol pyrolysis. The reaction is best explained in terms of an intimate ion pair type of mechanism.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/kin.550190303
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  • 59
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    Erratum (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 487-487 
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    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550190507
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  • 60
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    Kinetics, mechanism, and stereochemistry of Diels-Alder reactions of carbonyl-substituted ethenes with cyclohexa-1,3-diene in the gas phase (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 1063-1072 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of the Diels-Alder additions of CH2 — CHCHO, CH2—C(CH3)CHO, and CH2—CHC(CH3)O to cyclohexa-1,3-diene (CHD) have been studied in the gas phase. The stereochemistry and the mechanism of these reactions are discussed. In contrast with other Diels-Alder additions involving CHD as diene, a biradical mechanism does not fit the experimental results.
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    URL: http://dx.doi.org/10.1002/kin.550191203
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  • 61
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    Photoenhancement of the nitrous acid formation in the surface reaction of nitrogen dioxide and water vapor: Extra radical source in smog chamber experiments (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 539-551 
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    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The surface reaction of NO2 and H2O vapor to emit HONO into the gas phase was studied in the evacuable and bakeable photochemical chamber under the irradiation of UV-visible light (≳ 290 nm). Kinetic analysis of the NO, NO2, and HONO with the aid of computer modeling strongly suggested that the formation of HONO by the surface reaction is photoenhanced. When a linear regression was assumed, the photoenhancement factor defined by {(k′21/k21) - 1} was expressed as (6.8 ± 2.5)k1 under our experimental conditions, where k1 is the primary photolysis rate of NO2, and k21, k′21 are the second-order-equivalent rate constants of the HONO formation reaction in dark and under irradiation, respectively. The discussion was made that this photocatalitic enhancement of HONO formation would explain the nature of the extra OH radical flux in the smog chamber experiments, which has been discussed as “unknown radical source” and has still been unexplained by the surface dark reaction of NO2 and H2O to emit HONO.
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    URL: http://dx.doi.org/10.1002/kin.550190606
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  • 62
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    Electronic Resource
    Masthead (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987) 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550190701
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  • 63
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    Kinetic study of gas-phase reactions with CF2Cl2 and CFCl3. Analysis using the transition state theory (TST) of the chlorine atom transfer reactions by CF3 and CH3 radicals from halomethanes (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 627-638 
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    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The following gas-phase reactions: were studied by the competitive method with CF3I as the source of radicals. The kinetic parameters obtained in the temperature range 533-613 K and 503-613 K respectively for chlorine atom transfer reactions are given by: \documentclass{article}\pagestyle{empty}\begin{document}$$ \log k_1 /k_c ^{1/2} ({\rm cm}^{\rm 3}\, {\rm mol}^{{\rm - 1/2}} s^{ - 1/2}) = (6.19 \pm 0.10) - (16900 \pm 100)/\theta $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ \log k_2 /k_c ^{1/2} ({\rm cm}^{\rm 3}\, {\rm mol}^{{\rm - 1/2}} s^{ - 1/2}) = (6.52 \pm 0.10) - (14890 \pm 100)/\theta $$\end{document} where θ = 2.303 RT (cal mol-1).The Arrhenius A values were calculated for seven chlorine atom transfer reactions (CF2Cl2, CFCl3, CCl4 with CF3 radicals; CF3Cl, CF2Cl2, CFCl3 and CCl4 with CH3 radicals) by using the thermochemical kinetic version of the Transition State Theory (TST).
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  • 64
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    Self-inhibition or the lack of it in the pyrolyses of neopentane and n-hexane (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 649-658 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Published data show that in its early stages (up to 3% decomposition), the pyrolysis of n-hexane in the ranges 723-823 K and 10-100 Torr is not inhibited by the olefin products, in contrast with neopentane pyrolysis which is very strongly inhibited in similar conditions. Detailed consideration of the chain mechanisms for the two pyrolyses shows that the reactivity of the chain terminating radical towards hydrogen abstraction from an allylic C—H bond in product olefin is the factor which determines whether or not observable self-inhibition occurs. Thus, n-hexane pyrolysis, whose chain decomposition is terminated by recombination and disproportionation of ethyl, is not significantly self-inhibited, whereas that of neopentane which is terminated by recombination of methyl is very strongly inhibited because methyl is 14× more reactive than ethyl. The implications for other alkanes are briefly discussed.
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    The kinetics and mechanisms of the gas phase elimination of 4-(methylthio)-1-butyl acetate and 1-chloro-4-(methylthio)-butane (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 683-690 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The gas phase elimination of 4-(methylthio)-1-butyl acetate and 1-chloro-4-(methylthio)-butane has been investigated in a seasoned, static reaction vessel over the temperature range of 310-410°C and the pressure range of 46-193 Torr. The presence of the inhibitors propene, cyclohexene, and/or toluene had no effect on the rates. The reactions are homogeneous, unimolecular, and obey a first-order rate law. The rate coefficients are given by the following Arrhenius equations: for 4-(methylthio)-1-butyl acetate, log k1(s-1) = (12.32 ± 0.29) - (192.1 ± 3.6) kJ/mol/2.303RT; for 1-chloro-4-(methylthio)-butane, log k1(s-1) = (12.23 ± 0.59) - (175.7 ± 6.8) kJ/mol/2.303RT. The CH3S substituent in 1-chloro-4-(methylthio)-butane has been found to participate in the elimination reaction, where tetrahydrothiophene and methyl chloride formation may result from an intimate ion-pair type of mechanism. The yield of a cyclic product in gas phase reactions provides additional evidence of an intimate ion pair mechanism through neighboring group participation in gas phase elimination of special types of organic halides.
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    Kinetics of the permanganate oxidation of formic acid in aqueous solution (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 741-755 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of the permanganate oxidation of formic acid in aqueous perchloric acid at 30°C were examined by the spectrophotometric method. The chemical reaction 2MnO4- + 3HCOOH + 2H+ → 2MnO2 + 3CO2 + 4H2O, appears to proceed via several parallel reactions. The overall rate equation has been obtained by using statistical multilinear regression analysis of the 660 cases studied, and the presence in the rate equation of two new terms in relation to previous studies shows that both permanganate autocatalytic effects and acid media inhibition must be taken into account when the reaction proceeds at constant ionic strength.
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    On the mechanism of the azide-bromine reaction in aqueous medium (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 777-780 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550190809
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    A structure-activity relationship for the estimation of rate constants for the gas-phase reactions of OH radicals with organic compounds (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 799-828 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A previous technique for the calculation of rate constants for the gas-phase reactions of the OH radical with organic compounds has been updated and extended to include sulfur- and nitrogen-containing compounds. The overall OH radical reaction rate constants are separated into individual processes involving (a) H-atom abstraction from C—H and O—H bonds in saturated organics, (b) OH radical addition to 〉C=C〈 and —C≡C— unsaturated bonds, (c) OH radical addition to aromatic rings, and (d) OH radical interaction with —NH2, 〉NH, 〉N—, —SH, and —S— groups. During its development, this estimation technique has been tested against the available database, and only for 18 out of a total of ca. 300 organic compounds do the calculated and experimental room temperature rate constants disagree by more than a factor of 2. This suggests that this technique has utility in estimating OH radical reaction rate constants at room temperature and atmospheric pressure of air, and hence atmospheric lifetimes due to OH radical reaction, for organic compounds for which experimental data are not available. In addition, OH radical reaction rate constants can be estimated over the temperature range ca. 250-1000 K for those organic compounds which react via H-atom abstraction from C—H and O—H bonds, and over the temperature range ca. 250-500 K for compounds containing 〉C=C〈 bond systems.
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    The mechanism of thermal eliminations part XXIII: [1] The thermal decomposition of pyruvic acid (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 709-713 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal decomposition of pyruvic acid into carbon dioxide and acetaldehyde is a unimolecular first-order reaction and takes place according to the rate equation, logk = 13.53-41,250/4.575 K. These parameters contrast markedly with those recently reported, viz. logk = 7.19-27,700/4.575 K and confirm that the latter, which gave an unacceptably low value for the frequency factor, are anomalous. The lower reactivity of pyruvic acid compared to oxalic acid is interpreted in terms of normal electronic effects.
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    Masthead (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987) 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550190401
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  • 71
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    Laser pyrolysis studies of OH reaction rates with several butenes at 1200 K (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 269-276 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using a laser pyrolysis/laser fluorescence method, we have measured the rate constants for OH reacting with 1-butene, t-2-butene, isobutene, and 2,3-dimethyl-2-butene near 1200 K. The butene rate constants are large, ranging from 2.0-3.7 × 10-11 cm-3 s-1, and increase with the number of allylic hydrogens. Transition-state theory considerations indicate these allylic hydrogens are easily abstracted, in contrast to prior observations on propene.
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  • 72
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    Kinetics of cerium(IV) oxidation of macrocyclic complexes of chromium(III) and fate of chromium(IV) intermediates (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 277-298 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Kinetics and mechanism of the cerium(IV) oxidation of Cr(III) complexes of a series of macrocyclic (or pseudomacrocyclic) ligands with [14]-membered intraligand ring-sizes have now been investigated at I = 1.0 M (LiClO4) Temp. 30°C. The complexes of the formulation Cr(macrocycle)(X)(H2O)(3-n)+ where X = CHCl2 and H2O, n = 0 or 1 undergo oxidation to Cr(VI) with the formation of chromium(IV) intermediates. The observed kinetic parameters for the Ce(IV) oxidation of Cr(III) macrocyclic complexes have been discussed in terms of changes brought about by the macrocyclic ligands on the Cr(III) - Cr(IV) redox potentials and in specific rates for Cr(IV) - Cr(V) conversion. On the basis of this study, it has been suggested that the trapping of Cr(IV) is easier when a macrocyclic ligand having a symmetrical intra-ligand ring size and unsaturation in the cyclic structure is coordinated equatorially. Cyclic voltammetric studies indicate the formation of Cr(IV) transient in the case of electrochemical oxidation of trans-Cr(Me4[14]tetraene)(H2O)23+.
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    Kinetics of the gas-phase reactions of NO3 radicals with a series of alkynes, haloalkenes, and α,β-unsaturated aldehydes (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 299-307 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rate constants for the gas-phase reactions of NO3 radicals with a series of alkynes, haloalkenes, and α,β-unsaturated aldehydes have been determined at 298 ± 2 K using a relative rate technique. Using rate constants for the reactions of NO3 radicals with ethene and propene of (1.1 ± 0.5) × 10-16 cm3 molecule-1 s-1 and (7.5 ± 1.6) × 10-15 cm3 molecule-1 s-1, respectively, the following rate constants (in units of 10-16 cm3 molecule-1 s-1) were obtained: acetylene, ≤0.23; propyne, 0.94 ± 0.44; vinyl chloride, 2.3 ± 1.1; 1,1-dichloroethene, 6.6 ± 3.1; cis-1,2-dichloroethene, 0.75 ± 0.35; trans-1,2-dichloroethene, 0.57 ± 0.27; trichloroethene, 1.5 ± 0.7; tetrachloroethene, 〈0.4; allyl chloride, 2.9 ± 1.3; acrolein, 5.9 ± 2.8; and crotonaldehyde, 41 ± 9. The atmospheric implications of these data are discussed.
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    URL: http://dx.doi.org/10.1002/kin.550190404
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  • 74
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    Kinetics, mechanism, and stereochemistry of Diels-Alder reactions of CN-substituted ethenes with cyclohexa-1, 3-diene in the gas phase (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 363-371 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of the Diels-Alder additions of CH2 = CHCN, CH2 = C(CH3) CN, and cis- and trans-CH3CH = CHCN to cyclohexa-1, 3-diene have been studied in the gas phase. The stereochemistry of these reactions is discussed. In terms of a biradical mechanism, a minimum value of 4.1 ± 0.8 kcal mol-1 for the stabilizing effect of a CN group vis-à-vis a methyl group is shown to fit the experimental activation energies.
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    Absolute rate constants for hydrogen abstraction from hydrocarbons by the trichloromethylperoxyl radical (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 309-317 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Absolute rate constants have been measured for the reactions of trichloromethylperoxyl radicals with cyclohexane, cyclohexene, and hexamethylbenzene. The CCl3O2 radicals were produced by pulse radiolysis of air-saturated CCl4 solutions containing various amounts of the hydrocarbons. The rate constants were determined by competition with the one-electron oxidation of metalloporphyrins, using the rate of formation of the metalloporphyrin radical cation absorption to monitor the reaction by kinetic spectrophotometry. The rate constants for hydrogen abstraction from cyclohexane, cyclohexene, and hexamethylbenzene were found to be 1 × 103, 1.0 × 105, and 7.5 × 104 M-1 s-1, respectively.
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    The O + NH3 reaction: A review (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 319-362 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Experimental data for the reaction of O atoms with NH3 have been reviewed with particular attention to the possible effects of secondary reactions on the deduced rate coefficient. A reaction mechanism was assembled and computer calculations carried out to simulate several sets of experiments. The sensitivity of the calculations to uncertainties in the various rate coefficients was assessed. Transition-state theory calculations were carried out on the rate coefficient k1 for the O + NH3 → OH + NH2 reaction. These studies suggest that the reaction stoichiometry is dependent on temperature, initial reagent ratios, and extent of reaction; that available data are not sufficient to determine whether the initial step is H-atom abstraction (producing OH and NH2 radicals) or O-atom addition (producing an NH3O* complex): and that the low temperature values of k1 (T ≤ 400 K) are not consistent with values deduced at higher temperatures if the reaction proceeds by H-atom abstraction. Taking all the evidence into account, it is recommended that the expression 1.1 × 103 T2.1 exp(-2620/T) L mol-1 s-1 be used for k1 until more definitive experimental measurements are made at low temperatures.
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  • 77
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    Masthead (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987) 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550190501
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    Decomposition of the t-butoxy radical  -  I. Studies over the temperature range 402-443 K (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 391-400 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: By allowing the t-butoxy radical to decompose in the presence of nitric oxide, it has been possible to determine rate constants for decomposition by the measurements of the relative rates (2) and (3) Process (3) is clearly pressure dependent. The value of k3(∞) has been determined in the presence of several inert gases (CF4, SF6, N2, and Ar) and a value of k3 interpolated for atmospheric conditions. The results may be compared with those for other relevant alkoxy radicals at room temperature. Extrapolated values for k3 in the presence of CF4 lead to the result \documentclass{article}\pagestyle{empty}\begin{document}$$ k_3 (\infty)/s^{ - 1} = 10^{14.6 \pm 0.6} \exp (- 8052 \pm 604/T) $$\end{document}
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    Disproportionation-combination rate constant ratios for haloalkyl radicals: Evidence for heterogeneous disproportionation (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 401-413 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Disproportionation-combination rate constant ratios, kd/kc, have been determined for R + RCH2CHCl and for the auto disproportionation-combination of RCH2CHCl radicals, R = CF3, C2F5, and C3F7. The kd/kc for R = CF3 and to a lesser degree for R = C2F5 and C3F7 were very sensitive to the surface/volume ratio of the reaction vessel suggesting a heterogeneous component for disproportionation.
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  • 80
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    Collisional energy transfer in highly vibrationally excited molecules: A very low-pressure pyrolysis study of acetyl chloride (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 373-389 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The average downward energy transfer (〈Δ Edown〉) is obtained for highly vibrationally excited acetyl chloride with Ne and C2H4 bath gases at ca. 870 K. Data are obtained by the technique of very low-pressure pyrolysis (VLPP). Fitting these data by solution of the appropriate reaction-diffusion integrodifferential master equation yields the gas/gas collisional energy transfer parameters: 〈Δ Edown〉 values are 220 ± 10 cm-1 (Ne bath gas) and 330 ± 20 cm-1 (C2H4).These energy transfer quantities are much less than those predicted by statistical theories, or those observed for similar sized molecules such as CH3CH2Cl. These results are explained by the qualitative predictions of the biased random walk model wherein the fundamental mechanism of energy transfer is the multiple interactions between the bath gas and the individual atoms of the reactant molecule, during the course of the collision event. The charge distribution of acetyl chloride decreases the number of such interactions, thereby reducing the amount of energy transferred per collision.
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    Artificial-intelligence-based interpretation of feature sensitivities of the Belousov-Zhabotinsky reaction (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 435-455 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new approach is presented for analyzing kinetic models of relaxation-type oscillatory systems on the basis of numerical data. Feature sensitivities of the length of the two kinetic states of the Belousov-Zhabotinsky (BZ) reaction with respect to the rate constants of the model are explained by means of a logic-based inference system. The main kinetic roles of the individual reaction steps on the relaxing components are revealed, and a consistent interpretation of the kinetic states is given by this process. Both the high and the low set of rate constants were studied. According to our analysis, the bromous acid-hypobromous acid reaction is an important Br- producing step of the model, and in the case of the low set, the bromate-bromous acid reaction is not the rate-determining step of the bromous acid autocatalysis.
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    The mechanisms of the homogeneus, unimolecular elimination kinetics of ethyl 4-chlorobutyrate and 4-chlorobutyric acid in the gas phase (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 789-797 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ethyl 4-chlorobutyrate, which is reexamined, pyrolyzes at 350-410°C to ethylene, butyrolactone, and HCl. Under the reaction conditions, the primary product 4-chlorobutyric acid is responsible for the formation of γ-butyrolactone and HCl. In seasoned vessels, and in the presence of a free-radical inhibitor, the ester elimination is homogeneous, unimolecular, and follows a first-order rate law. For initial pressures from 69-147 Torr, the rate is given by the following Arrhenius expression: log k1(s-1) = (12.21 ± 0.26) - (197.6 ± 3.3) kJ mol-1 (2.303RT)-1. The rates and product formation differ from the previous work on the chloroester pyrolysis.4-Chlorobutyric acid, an intermediate product of the above substrate, was also pyrolyzed at 279-330°C with initial pressure within the range of 78-187 Torr. This reaction, which yields γ-butyrolactone and HCl, is also homogeneous, unimolecular, and obeys a first-order rate law. The rate coefficient, is given by the following Arrhenius equation: log k1(s-1) = (12.28 ± 0.41) - (172.0 ± 4.6) kJ mol-1 (2.303RT)-1. The pyrolysis of ethyl chlorobutyrate proceeds by the normal mechanism of ester elimination. However, the intermediate 4-chlorobutyric acid was found to yield butyrolactone through anchimeric assistance of the COOH group and by an intimate ion pair-type of mechanism. Additional evidence of cyclic product and neighboring group participation is described and presented.
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    Masthead (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987) 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080101
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  • 84
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    Recursion formulae for calculation of overlap integrals (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 1-5 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Multi-ζ Slater-type orbitals are frequently used in molecular orbital calculations. Master formulae and numerical tables are available in literature for overlap integrals between s, p, and d atomic orbitals up to principal quantum number (n) = 3 and for some other selected quantum numbers. However, no master formula or numerical table is available for quantum numbers n = 5 and above and involving ƒ orbitals. In this article recursion formulae have been presented for the calculation of the overlap integral between any two s, p, d, and ƒ atomic orbitals formed by a linear combination of Slater-type orbitals. These formulae, when expanded, would give rise to all the master formulae reported in the literature as well as formulae hitherto unreported.
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    Molecular modeling of polymers: I. Correct and efficient enumeration of intrachain conformational energetics (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 28-38 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Polymer conformational analyses can require being able to model the intramolecular energetics of a very long (infinite) chain employing calculations carried out on a relatively short chain sequence. A method to meet this need, based upon symmetry considerations and molecular mechanics energetics, has been developed. Given N equivalent degrees of freedom in a linear polymer chain, N unique molecular groups are determined within the chain. A molecular unit is defined as a group of atoms containing backbone rotational degrees of conformational freedom on each of its ends. The interaction of these N molecular groups, each with a finite number of nearest neighbors, properly describe the intramolecular energetics of a long (infinite) polymer chain. Thus, conformational energetics arising from arbitrarily distant neighbor interactions can be included in the estimation of statistical and thermodynamic properties of a linear polymeric system. This approach is called the polymer reduced interaction matrix method (PRIMM) and the results of applying it to isotactic polystyrene (I-PS) are presented by way of example.
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    URL: http://dx.doi.org/10.1002/jcc.540080104
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  • 86
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    Recent advances in multireference second order perturbation CI: The CIPSI method revisited (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 39-47 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The evolution of the CIPSI method, with the latest modifications recently implemented in our laboratory, is described. A new version, based on a diagrammatic technique, is presented. Test calculations which have been run on water, ethylene, and transacrolein, show that the new method is a powerful tool for the study of medium-size molecular systems.
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    URL: http://dx.doi.org/10.1002/jcc.540080105
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    The role of d functions in ab initio calculations. II. The deformation densities of SO2, NO2, and their ions (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 6-27 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Comparison of the optimized geometries and SCF energies for the series XO2+, XO2, XO2-, XO2-, with X = S,N shows that d(S) functions cause larger bond shortening and energy drop than d functions centered on first-row atoms. This is further emphasized on comparing the separate effects of d(central atom) and d(O) functions for SO2 and NO2-, which are similar only for the first-row molecule. The d(S) functions are also essential for proper prediction of the OSO angles. The deformation densities calculated for each series and the corresponding X-O shared populations, change as expected on adding electrons first into σ* then into π* molecular orbitals. In the regions around nuclei the deformation densities express the behavior of the atomic s and p valence orbitals or of their product inside their radial nodes. Introduction of d functions causes substantial polarization effects. For X = N these are mostly local except in the bonding regions where d(N) and d(O) functions are somewhat interchangeable. However, d(S) functions induce also unique changes in the deformation density near O. They cause π and π′ charge migration from O to S and a σ flow in the opposite direction. These effects are largest for the hypervalent species. The unique populations of the d(S) functions are much larger than those of d(N) and d(O) functions. The contribution of d(S) functions to bonding is related to the larger amplitude at small radii of the atomic 3d(S) orbital as compared with that of 3d(N). The difference in amplitudes is related to penetration effects. Diffuse p functions affect geometries and SCF energies of doubly, but not singly negative ions. However, they mostly describe the diffuse nonbonding clouds and do not affect bonding patterns.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540080103
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    On the importance of size-consistency corrections in semiempirical MNDOC calculations (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 48-50 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Energies obtained by configuration interaction calculations including all double excitations with regard to the Hartree-Fock reference determinant can empirically be corrected to size consistency using either the Langhoff-Davidson (LD) formula or a formula suggested by Pople, Seeger, and Krishnan (PSK). Semiempirical MNDOC calculations suggest that for molecular systems with a large number of electrons and important correlation effects the PSK correction is superior to the LD correction.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080106
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  • 89
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    Ab initio studies on van der Waals molecules. A comparative study with several basis sets of the C2v HeLi2 systemThis work was financially supported by the CAICYT No. 0637/81. (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 51-56 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The potential energy surface of the van der Waals system HeLi2 is computed for the case in which the system has C2v symmetry and at the Li-Li distance (5.005 bohrs). A comparative study of the results for the two methods used, ab initio Hartree-Fock and second-order Møller-Plesset, and several basis sets, ranging from minimal to near Hartree-Fock quality, is also done. The results show the importance of correcting the basis set superposition error, and the need, in order to obtain a good description of the potential, of basis sets with polarization functions on all the atoms, when the Møller-Plesset method is used. At the Hartree-Fock level, the MINI-1 basis gives results almost of the same quality as the near Hartree-Fock basis.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080107
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  • 90
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    Theoretical study of water-pyridine complexes using intermolecular potentials (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 67-80 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Intermolecular potential functions have been used to determine the equilibrium structures of the water-pyridine complexes. The dimer and symmetrical 2:1 water pyridine systems have been studied. Three water models, ST2, TIPS2, and EMPWI have been combined with two different Lennard Jones nonbonded parameters and various charge distributions for the pyridine molecule to describe the systems. For the dimer, results show two distinguishable classes of preferential hydration sites, which are specific sites corresponding to hydrogen-bonded dimer and nonspecific sites located near the hydrophobic regions. Calculations performed on hydrogen-bonded symmetrical complexes show that the planar complex is generally less stable than the complex with water molecules perpendicular to the pyridine plane. For these complexes, the major factor that influences the hydrogen-bonded configurations is the choice of the water model. The importance of atomic charge distributions for the solute over the choice of potential parameters is pointed out. Finally, the effective lone pair representation on the aromatic nitrogen atom is shown to improve the hydrogen bond geometry and the stability of the complexes.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080109
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  • 91
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    Polarization counterpoise corrections to correlated hydrogen bond interaction energies (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 81-83 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Basis set superposition error in hydrogen-bonded systems can exaggerate attraction calculated from self-consistent field energies as well as from electron correlation energies. One cause of this error is the basis set deficiency in describing the charge polarization of one constituent molecule when its bonding partner approaches. That constituent molecule's description is improved partly because of the proximity of the partner's basis functions, independent of real attraction. That polarization-related error is shown to occur primarily at the SCF level and not at correlated levels.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080110
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  • 92
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    Masthead (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987) 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080201
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  • 93
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    Ab initio calculations on the effect of polarization functions on disiloxane (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 84-93 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The effect of polarization functions for ab initio molecular orbital calculations at the 3-21G* level has been studied for disiloxane. Calculated molecular geometry, dipole moment, and the linearization barrier variation were analyzed for different uncontracted polarization functions. It was concluded that variation of the polarization function on oxygen has only a minor influence on the molecular properties of disiloxane, but its presence is required to obtain a bent geometry for the disiloxane bond. The calculated molecular properties of disiloxane are greatly influenced when the polarization function on silicon is varied. Two different values (0.3 and 0.9) for the exponent of the silicon polarization function provide results comparable to the experimental values for disiloxane. The only significant differences between the results obtained from ab initio calculations using the two polarization functions are in net atomic charges. The uncontracted polarization function of silicon with a value of 0.3 for its exponent is transferable to other organosilicon compounds. Calculated molecular geometries of flexible or rigid structures are in very good agreement with the experimental values.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080111
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  • 94
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    Optimized method for the evaluation of the convolutionally distorted decay curves (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 95-106 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A nonlinear least squares procedure based on the Meiron method is described for the evaluation of the convolutionally distorted decay curves consisting of exponentials. Most of the special procedures are well known and the selected ones proved to be the most effective. Some new procedures are introduced to facilitate the evaluation work and literature data are analyzed as an example.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080202
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  • 95
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    Combination of MOMM and VEH methods to calculate electronic properties of polymers (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 107-116 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A Molecular-Orbital-Based Molecular Mechanics method (MOMM) has been employed to calculate the structures of cyclopentadiene, pyrrole, furan, thiophene, dibenzocyclopentadiene (fluorene), dibenzopyrrole, dibenzofuran, and dibenzothiophene. The dimer structures of the above compounds have also been calculated using the same method to derive the unit cells of polycyclopentadiene, polypyrrole, polyfuran, polythiophene, polydibenzocyclopentadiene, polydibenzopyrrole, polydibenzofuran, and polydibenzothiophene. The band structures, densities of states, ionization potentials, band gaps, reduction potentials, and oxidation potentials of these polymers then have been calculated by using the Valence Effective Hamiltonian method (VEH). The structural effects on electronic properties are discussed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080203
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    Reliable Gaussian basis sets for closed-shell atoms (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 117-131 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Medium size Gaussian basis sets for inert-gas atoms (from neon to xenon) have been constructed using the energy optimization method which maintains reliable description of the long-range valence atomic region. These basis sets have been tested in SCF calculations on homonuclear inert-gas dimers. For Ne2, Ar2, and Kr2, the present results have been analyzed carefully and compared with those obtained using extended basis sets (for Kr2 extended benchmark calculations are also reported). Our interation energies agree well with accurate values and are compared with experimental data. For Ne2 and Ar2, detailed studies of basis set superposition error also are presented.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080204
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    Hydration structures and energetics of phospholipid (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 57-66 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Using previously reported ab initio potentials of the intermolecular interaction energies of phospholipid (PL), Lysophosphatidyl Ethanolamine, with one Na+ ion and one water molecule, we performed Monte Carlo simulations for PL-water and PL-Na+-water systems. Water-water and PL-water interaction energetics of PL hydration sites are analyzed to understand, in a qualitative way, why the PL head part shows hydrophilicity and the tail part shows hydrophobicity. The interaction of Na+ with PL, as well as the interaction of water with PL, is visualized from the analysis of the hydration structures near PL, and the radial distribution functions are analyzed for selected hydration sites. The PL molecule shows much stronger interaction with Na+ than with water. The Na+ ion is likely to be strongly bound to PO4-, even to the extent of being trapped, whereas, for water, there exist two strong binding regions near NH3+ and PO4-. Three water molecules near NH3+ are much more strongly bound than four water molecules near the double-bonded oxygens of PO4-. The hydrogens of CH2 adjacent to NH3+ show somewhat strong hydrophilicity, while the hydrogens of CH2 adjacent to PO4- does not show such characteristics. The CH2 groups at the PL tail part give repulsive interactions with water molecules, showing hydrophobicity. Water molecules near the PL tail are stabilized only by water-water interactions.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080108
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  • 98
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    The ellipsoid algorithm as a method for the determination of polypeptide conformations from experimental distance constraints and energy minimization (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 132-141 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A new method for constrained nonlinear optimization known as the ellipsoid algorithm is evaluated as a means of determining and refining the conformations of peptides. Advantages of the ellipsoid algorithm over conventional optimization methods include that it avoids many local minima that other methods would be trapped by, and that it is sometimes able to find optimum solutions in which the constraints are satisfied exactly. The dihedral angles about single bonds were used as variables to keep the dimensionality low (the rate of convergence decreases rapidly with increasing dimensionality of the problem). The method is evaluated on problems involving distance constraints, and for minimization of conformational energy functions. In an initial application, conformations consistent with an experimental set of NMR distance constraints were obtained in a problem involving 48 variable dihedral angles.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080205
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  • 99
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    Quantum mechanical modeling of a transannular interaction in a bicyclic amidinium ion (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 149-157 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A transannular donor-acceptor interaction in a bicyclic azaamidinium salt was modeled by quantum mechanical calculations using a supermolecule complex consisting of a formamidinium cation and an ammonia molecule. Molecular properties are reported at various geometries. These results are compared with the results of similar calculations on the bicyclic cation itself. The model calculations and the bicyclic cation calculations are in good agreement, but both fail to reproduce the experimentally known structure. Results from ab initio calculations on the model system are discussed, as are results from calculations which included iodide as counterion.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080207
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  • 100
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    Comparison of the use of the MNDO and MINDO/3 methods with ab initio methods to study tautomerism in histamine, 2- and 4-methylhistamine (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 142-148 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The semiempirical MNDO and MINDO/3 methods are used to study the various tautomeric forms of histamine, 2-methylhistamine, and 4-methylhistamine. Comparisons of the optimized structures and tautomerization energies are made with values obtained from ab initio Hartree-Fock calculations using the 3-21G and STO-3G basis sets. Based on these results and previous comparisons of STO-3G results with x-ray structures, the present results indicate that while there are some differences in the values of the structural parameters, the changes in structure upon tautomerization and/or protonation are very similar. Further analysis of the MNDO and MINDO/3 structures by means of their utilization in 3-21G and STO-3G calculations indicates that either of these semiempirical methods provides reliable values for the structural parameters. Both methods give good qualitative agreement with the ab initio calculations for the relative energies of the various tautomers in the three compounds. In these studies the MNDO method appears to give better quantitative agreement with the 3-21G and STO-3G results than the MINDO/3 method.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080206
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