Library

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 1990-1994  (232)
  • 1915-1919
  • 1890-1899
  • 1990  (232)
  • Physical Chemistry  (232)
  • 101
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 443-448 
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Two types of equivalents for the aldo and the keto groups have been developed, the Schleyer and the bond separation energy (BSE) equivalents. The equivalents were used to give the heats of formation and the BSE of unstrained models. These equivalents were then used in the calculations of the strain energies for aldehydes and ketones. The results obtained were compared with MM2 values. The equivalents were also used in calculations of the stabilization (destabilization) energies for conjugated carbonyl compounds. The results obtained correlate well with the available experimental data.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 102
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 428-434 
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effect of added alkali metal perchlorates on the rate of lactonization of ω-bromoalkanoate ions was investigated in 99% dimethyl sulphoxide (four-membered ring formation) and in dimethylformamide (DMF) (four- and sixteen-membered ring formation). In all cases the effect of the added metal salts is rate depressing, as a result of the lower reactivity of metal ion-associated species relative to the free ions. Ion-pairing association constants were determined, but the reactivity of ion pairs were so low as to elude direct measurement in most cases. Evidence was also obtained for the formation of ion triplets with Li+ in DMF. The relevance of the present results in connection with the ‘caesium effect’ is briefly discussed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 103
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 470-476 
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Ab initio theoretical calculations were carried out on the three tautomers, NH, OH and CH, of 1,2,6-thiadiazine 1,1-dioxides. Different basis sets were employed in order to obtain an adequate description of these cyclic sulphamide derivatives. A coherent picture is obtained which includes relative stability of tautomers (NH 〉 CH 〉 OH), non-planarity of NH and CH tautomers and electronic distribution (Boys' localized orbitals).
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 104
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990) 
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 105
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 687-693 
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The electrochemical behaviour of seven N-hydroxy-N-arylacetamides (RNOHCOCH3, R = phenyl, 4-chlorophenyl, 3,4-dichlorophenyl, 4-ethoxyphenyl, 4-biphenylyl, 2-fluorenyl and 2-phenanthryl) was investigated by cyclovoltammetry. Each compound showed two different oxidation potentials, attributed to a quasi-reversible one-electron transfer in the range between 0·55 and 0·63 V and an irreversible transfer of a second electron between 0·80 and 1·20 V. Since the one-electron oxidation of N-hydroxy-N-arylacetamides gives the corresponding nitroxides, the kinetics of the self-reaction of these radicals and the concentration dependence of the product pattern were also studied.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 106
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990) 
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 107
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 13-16 
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A model is proposed for the quantification of resonance in thioamides. The percentage resonance and CS and CN bond distances predicted from the model are reported and the results are compared with those for the corresponding amides.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 108
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 55-61 
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Rates of loss of tritium from p-nitrophenylnitromethane-α-t in toluene solution catalyzed by a series of amine bases show that hydrogen exchange in this system occurs at the same rate as ionization of the carbon acid, and that internal return is not taking place. This substantiates a previous suggestion that very large deuterium isotope effects reported for some of these reactions and attributed to extensive tunnelling were determined under conditions where the isotopic label was being lost and are therefore artifacts. This study provides isotope effects which are generally much smaller than those reported previously, but some tunnelling may still be taking place in some of these reactions.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 109
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 41-47 
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The kinetics of the reactions of 1-chloro-, 1-fluoro- and 1-phenoxy-2,4-dinitrobenzene with piperidine, n-butylamine and benzylamine, and in the case of the ether, morpholine were studied as functions of nucleophile, DABCO and pyridine concentrations in tetrahydrofuran and ethyl acetate. The reactions of the ether with n-butylamine and benzylamine in benzene were also studied as functions of nucleophile, DABCO and pyridine concentrations. A comparison with results in the literature indicated that the reactions in tetrahydrofuran and ethyl acetate resemble those in dipolar aprotic solvents when primary amines are the nucleophiles and those in aprotic solvents when the nucleophile is a secondary amine. An explanation is suggested for the observation that whereas the reactions of 1-phenoxy-2,4-dinitrobenzene with piperidine and morpholine in both tetrahydrofuran and ethyl acetate are strongly catalysed by the nucleophiles, they are not catalysed by pyridine and there is either extremely weak or no catalysis by DABCO.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 110
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990) 
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 111
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 81-88 
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: MNDOC-CI results are reported for the photochemical α-cleavage reaction of carbonyl compounds. Potential energy surfaces for some excited singlet and triplet states and cross-sections along the bitopic reaction path show that the activation energy of the α-cleavage reaction is determined by the relative energetic position of the lowest two triplet states. The reactivity of aliphatic ketones depends only on the degree of branching at the α-carbon, because the triplet barrier is due to an (avoided) crossing of two surfaces corresponding to an nπ* and ππ* excitation respectively, which correlates with the stability of the leaving alkyl radical. For conjugated carbonyl compounds, on the other hand, the position of the crossing point is independent of the 3nπ* excitation energy, but if the 3ππ* surface is below the 3nπ* surface all the way along the reaction coordinate, the reaction is determined by the barrier on the 3ππ* surface and any additional stabilization of the 3ππ* state increases the barrier.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 112
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 119-125 
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Nuclear spin polarization effects observed during the electron transfer-induced cleavage of the trans head-to-head dimer of 3,3-dimethylindene are incompatible with the intermediacy of a single dimer radical cation. Instead, they are compatible with the ‘cooperative’ involvement of a localized, doubly linked and a delocalized, singly linked dimer radical cation. The mechanistic consequences for the cycloaddition and cycloreversion of radical cations are discussed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 113
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990) 
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 114
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 143-146 
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Analysis of the topological properties of the electron density distribution of cis-1,2-dinitrosoethene (I) shows that there is a normal covalent, albeit very long, single bond between the nitrogen atoms in the molecule, which is in fact the di-N-oxide of 1,2-diazacyclobutadiene (II). Despite its extraordinary length, the N—N bond is shown to be consistent with the strong correlation between the electron density at the bond critical points and the calculated bond lengths of N—N bonds. The geometry and electronic structure exhibit a number of remarkable features.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 115
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 174-180 
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The kinetics of the oxidation of a number of monosubstituted aryl methyl, alkyl phenyl, dialkyl and diphenyl sulphides by N-chloroacetamide (NCA) to yield the corresponding sulphoxides were studied. The reaction is first order with respect to the sulphide, NCA and hydrogen ions. There is no effect of added acetamide. Protonated NCA has been postulated as the reactive oxidizing species. The rates of oxidation of meta- and para-substituted phenyl methyl sulphides were correlated with Taft's and Swain's dual substituent parameter equations. For the para-substituted compounds, the best correlation is obtained with σI and σR+; the meta-substituted compounds correlate best with σI and σR° values. The reaction constants are negative. The oxidation rates of the ortho-substituted sulphides yield an excellent correlation in a triparametric equation involving Taft's σI and σR+ values and Charton's steric parameter, V. The oxidation of alkyl phenyl sulphides is susceptible to both polar and steric effects of the alkyl group. A mechanism involving the formation of a halogenosulphonium cation in the rate-determining step is proposed.
    Additional Material: 8 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 116
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Vector analysis of dipole moments of two series of nitrones revealed a mesomeric dipole moment compatible with a relatively great contribution of a zwitterionic structure and possible some contribution from a hypervalent structure. The latter was also suggested from a detailed comparison of bond lengths among several classes of compounds, involving the CNO grouping. Since both the C=N and N—O bonds seem to possess an appreciable double bond character, it is suggested that the N atom might be allocated more then eight valence electrons.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 117
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 205-208 
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The equilibrium adduct from the Michael reaction between lithium dimethylphenylacetamide enolate and methyl cinnamate has been studied by means of 7Li, 13C and 1H NMR and IR spectroscopy as well as by electrical conductivity measurements in THF and diethyl ether. The 7Li NMR and the electrical conductivity measurements data are consistent with a triple ion structure of [A-M+A-]- M+ type, favoured in THF. All other spectral data support an intramolecular chelation in the triplet fragment.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 118
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 230-234 
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The Stern-Volmer quenching equation for a photochemical reaction in the presence of internal filtering was obtained by applying the steady-state approximation to the system. The equation was used for the kinetic analysis of the Type II photoreaction of 2-benzoylcyclohexanone yielding 1-phenylhept-6-ene-1,3-dione, the enol form of which acts as an effective internal filter. The kqτ value for quenching of the photoreaction by 2,5-dimethylhexa-2,4-diene was determined to be 9·1 ± 0·5 l mol-1.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 119
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 255-259 
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The lone-pair charge, Qlpf, of a base B is a (theoretically calculated) measure of the amount of charge on the lone pair of B that binds to an acid Av (v = 0, 1) in an acid-base reaction. It is shown how they can be used for the quantitative study of structural effects on gas-phase proton affinities, vertical ionization potentials and hydrogen-bonding basicities.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 120
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 419-427 
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A method for relating averaged NMR parameters with point-by-point geometries for MM2 calculations is given for mobile molecules, e.g. δ-lactones. This method permits the identification of cis/trans geometry in cases where a complete set of isomers is not available. 2-Oxa-3r,4c,5t-triphenylcyclohexanone is prepared by condensation of 1,2-diphenylethanone with 3-phenylpropenal. The initially formed formed biscarbonyl adduct undergoes an internal Cannizzaro reaction forming a hydroxy ester, which lactonizes during work-up. The stereochemistry of the hydride transfer in the Cannizzaro reaction is consistent with the Felkin rule for asymmetric induction. The configurations of this and related lactones were studied through observation of NMR coupling constants, reductions to hemiacetals and molecular mechanics calculations. The most stable conformations are found to be a boat form for the parent lactone and a half-chair form for two isomers. The half-chair and boat forms lie near in energy for all isomers. The calculation techniques outlined illustrate that it is incorrect to consider only chair and boat forms; many intermediate conformations exist. Difficulties with previous IR methods of analysis are discussed.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 121
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The nature of the (Na-DB30C10)+ complex has been studied by 23Na NMR in four non-aqueous solvents: nitromethane (NM), acetonitrile (AN), acetone (AC) and pyridine (PY). The equilibrium constant of formation (Kf) of (Na-DB30C10)+ in AC, AN and PY was determined at 300 K: log Kf = 3·9 ± 0·3, 3·4 ± 0·5 and 3·0 ± 0·1, respectively. In cases such as in pyridine, where exact values of the rate constants for the chemical exchange could not be calculated, limiting values were determined giving k-1 (the rate constant for complex dissociation) 〉 6·6 × 10-4 s-1 and kc (the rate constant for the formation of the complex) 〉 5 × 107 l mol-1 s-1. Evidence was found for the formation of a 2 : 1 (Na2-DB30C10)+2 complex in nitromethane. It has been previously shown that for (Na-DB24C8)+ the first coordination sphere of Na+ is exclusively filled by the oxygens of the crown ether, whereas for (Na-DB18C6)+ there is participation of at least one solvent molecule. The first coordination sphere of Na+ in (Na-DB30C10)+ consists of one or several molecules of solvent in addition to a number of oxygens from the crown ether. The soft wrapping of the Na+ by DB30C10 is in constrast with the hard wrapping of Na+ by DB24C8 and of K+ by DB30C10.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 122
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The kinetics of the gas-phase elimination of two 2-haloethyl methanesulphonates were determined in a static system over the temperature range 310-380°C and pressure range 26-174 Torr. The reactions in seasoned vessels, with the free-radical inhibitor propene and/or toluene always present, are homogeneous and unimolecular, and follow a first-order rate law. The rate coefficients are given by the Arrhenius equations: for 2-bromoethyl methanesulphonate log k1 (s-1) = (11·70 ± 0·43)-(172·8 ± 4·8) kJ mol-1 (2·303RT)-1 and for 2-chloroethyl methanesulphonate log k1 (s-1) = (11·67 ± 0·50)-(173·9 ± 6·0) kJ mol-1 (2·303RT)-1. The bromo compound was found to be more reactive than the chloro compound. At 340°C, for Br k1 = 9·46 × 10-4 s-1 and for Cl k1 = 7·12 × 10-4 s-1. Apparently, electronic factors seem to be operating in these elimination reactions.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 123
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 477-481 
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Ab initio calculations were carried out on systems with a geometrically constrained relationship between a double bond and a homoallylic substituent X, as in YC=CCCX. The axial-equatorial equilibria in 3-substituted methylenecyclohexanes and 4-substituted cyclohexenes are determined largely by the homoallylic interaction between X and the double bond. The homoallyic substituent was chosen to be OCH3, and the nature of the double bond was varied by changing Y (H, CH3, F, Cl, CN). NMR experiments previously had found very significant dependences of the axial-equatorial equilibrium on the nature of the X and Y substituents. Electrostatic calculations, based on Mulliken charges, reproduce the experimental (NMR) substituent effects on the axial-equatorial equilibrium and suffice to explain all the observations.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 124
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 493-502 
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The stoichiometry of solvates formed in some binary solvent systems is presented and types of interactions in such systems are discussed based on changes in viscosity and dielectric properties.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 125
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 587-593 
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An analysis of the energy components of the conjugation energy between the substituent and the phenyl group in aniline and nitrobenzene showed that there are two types of conjugation: the conjugation energy in aniline, with an electron-donating substituent, is given by the decrease in the kinetic energy of elctrons, whereas that in nitrobenzene, with an electron-withdrawing substituent, is caused by the decrease in the potential energy. Physical interpretations are given of the arrows in the organic electron theory of these compounds.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 126
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 611-619 
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An MNDO study was made of the gas-phase thermal isomerization of isoxazole to explore theoretically the proposed reaction mechanism. The results showed that isoxazole isomerizes through an azirine, as an intermediate, to oxazole via a nitrile ylide or to ketenimine, with similar activation energies, and that the first step is rate limiting, in agreement with the experimental results. These results also show that isomerization to a nitrile is possible, but in this case the energy barrier is grater than the corresponding isomerization to oxazole. The MNDO study also supports a concerted process for the rate-limiting step, as reported earlier on the basis of experimental studies.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 127
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 635-638 
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Ab initio calculations with the 6-31G* basis set were carried out on planar and pyramidalized geometries of the 1,1,3,3-tetrafluoropropenyl anion and on two geometries with one CF2 group rotated out of conjugation. Structures with at least one pyramidalized CF2 group are substantially lower in energy than the corresponding unpyramidalized structures for both rotated and unrotated geometries. At the MP2/6-31G* level of theory, three structures of approximately equal energy all lie 17-18 kcal mol-1 below the planar C2v structure. These include a Cs geometry with one CF2 group rotated out of conjugation, an unrotated C1 structure with unequal CC bond lengths and an unrotated, pyramidalized C2 structure with equal CC bond lengths.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 128
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 651-658 
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The spectroscopic and physicochemical properties of parent azoles substituted on the nitrogen by a proton, a methyl group, a p-aminophenyl group and an acetyl group have been gathered. This information on azol-1-yl substituents has been treated by principal component analysis and partial least-squares analysis. The first result of these analyses is that it has been possible to complete some missing properties of azol-1-yl substituents, such as pKa for proton loss of some azoles and hydrolysis rates of certain azolides. Another significant result of the chemometric approach is the assignment of the 1-acetyltetrazole IR and NMR data to one of the two possible isomers.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 129
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Formation constants, K, for hydrogen bonding of weak C—H donors with hexamethylphosphoric triamide were measured in cyclohexane at 35°C by PMR spectroscopy; data were analyzed by the Higuchi method. Donors include terminal alkynes and series of polyfluoro-, polychloro- and polybromobenzenes. The K values for many of these are too small to measure in CCl4. For RC≡CH, K decreases in the order R = BrCH2 〉 C6H5 〉 C2H5O 〉 tert-butyl. For polyhalobenzenes, K is generally larger for F than Cl or Br, and meta halogens facilitate hydrogen bonding most effectively. Among tetrahalobenzenes, 1,2,3,4-isomers show the least evidence of 2:1 complex formation. Pentachlorobenzene has a smaller K than its 1,2,3,4-tetrachlor analog even after statistical correction; for C6HX5, K decreases in the order F 〉 Cl 〉 Br; the K values for 1,3,5-trihalobenzenes are closely similar; and 1,3,5-tribromo-2,4-dimethylbenzene shows no evidence of hydrogen bonding by PMR. The last three observations suggest that buttressing is important in the C6HX5 structure, at least with Cl and Br. A value of K for benzene was measured, suggesting for the first time that the H atoms of benzene engage in hydrogen bonding. The result compares well with values extrapolated from data for polyfluoro- but not polychlorobenzenes, again probably because of buttressing in the latter.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 130
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 694-696 
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Benzyloxyfluorocarbene resists fragmentation to benzyl fluoride, and can be intercepted by water, fluoride ion, methanol or acrylonitrile. In contrast, benzyloxybromocarbene and benzyloxychlorocarbene fragment to the corresponding benzyl halides, and are not efficiently trapped.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 131
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The method for determining the rates of formation of gaseous pyrolysis products during thermal decompositions by simultaneous thermogravimetric modulated beam mass spectrometry is presented. The analysis procedure that handles both molecular and continuum flow from the reaction cell is described. The technique is illustrated with the isothermal decomposition of HMX. The temporal behaviors of the rates of formation of the pyrolysis products, H2O, HCN, CO, CH2O, NO, N2O, methylformamide, C2H6N2O, and octahydro-1-nitroso-3, 5, 7-trinitro-1, 3, 5, 7-tetrazocene, formed during the isothermal decomposition of HMX at 211°C, are presented. The results show that a complex condensed-phase reaction mechanism controls the decomposition.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 132
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 243-252 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rate constants and activation parameters for the direct addition reaction of methyloxirane or ethyloxirane to alkyl-2-hydroxyalkyl sulfides or successive oxypropylene and oxybutylene adducts in the presence of basic catalysts were determined at 373-403 K. This reaction was found to be of the first order with respect to alkyloxirane, sulfide, and catalyst.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 133
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 321-329 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Kinetic parameters of the reaction of ozone with aliphatic alcohols of different structures are obtained. The ratio between the relative reactivities of the primary: secondary: tertiary alcohols was found to be 1:15:138. The bond energy changes in the same sense as the activation energy. The rate-controlling step of ozone reaction with alcohols is the abstraction of a hydrogen atom being in α-position with respect to the OH group. The pre-exponential factors (A) are calculated by the collision and activated complex methods and compared with the experimentally obtained values. The results from the calculations represent convincing evidence that the mechanism of the rate-controlling step of the reaction is associated with the formation of an activiated complex which has a linear shape ensuring free rotation of its fragments.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 134
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Excitation of Ru(bipy)32+ ion by visible radiation of wavelength λ = 436 nm in aqueous medium in presence of inorganic peroxides, peroxomonosulfate (PMS), peroxodisulfate (PDS), and peroxodiphosphate (PDP) was found to generate Ru(bipy)33+. The kinetics of this photochemical oxidation of Ru(bipy)32+ by each peroxide was followed spectrophotometrically and found to obey a total second-order, first-order each in [Ru(bipy)32+] and [peroxide]. In the absence of light, thermal reaction of PMS and PDS with Ru(bipy)32+ occurred but only when at 1.0 M [H+] and 〉 10-2M [peroxide]. The reaction of PMS with the complex is found to be cyclic, ie., Ru(bipy)33+ formed oxidizes PMS itself and such a reaction was not observed in the case of PDS and PDP. The effects of pH, [peroxide], and [Ru(bipy)32+] on the visible light induced oxidation of Ru(bipy)32+ by these peroxides are investigated. The results are discussed with suitable reaction mechanisms.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 135
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction rates of ethanolysis of ionized phenyl salicylate, PS-, have been studied in the presence of different concentrations of various inorganic and organic salts in ethanol-water solvent of different compositions. The observed pseudo first-order rate constants,k1, reveal a nonlinear increase with increase of thecontent of ethanol until it becomes ca. 85%, v/v. The rate constants, k1, begin to decrease with increase of ethanol content beyond ca. 85%, v/v. The observed data obtained at ethanol contents of 〈ca. 55%, v/v, follow the relationships k1 = k[EtOH]T/(1 + K[EtOH]T ) where k and K represent the second-order rate constant for thereaction of PS- with monomeric ethanol, EtOH, and association constant for dimerization of monomers of ethanol, respectively, and [EtOH]T is the total concentration of ethanol. The calculated values of k and K obtained in the presence of 0.01 M tetraalkylammonium ions, R4N+, show ca. 15% and 40%, respectively, decrease with increase of the chain lengths of alkyl groups, R. The following conclusions have been derived from the observed data. (i) Lithium chloride causes ethanol structure-making effect while NaCl, KCl, and CsCl show ethanol structure-breaking effect. (ii) Tetraalkylammonium halide salts such as Me4NCl, Et4NI, andn-Bu4NI reveal ethanol structure-breaking effect due to the transfer of some water molecules from solvation shells of ethanol and R4N+ when favorable hydrophobic interaction between hydrophobic sites of ethanol and R4N+ results in. This effect is, however, partially off set by the direct interaction between monomeric ethanol and R4N+. Both inorganic and organic cations are preferentially solvated by only water molecules in EtOH-H2O solvents with EtOH contents of 〈ca. 55%, v/v. The effects of 0.01 M LiOH on k1 values obtained within the ethanol content range of 35% to 97%, v/v, seemed to be unaffected due to the presence of 0.01 M NaCl.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 136
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990) 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 137
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 175-186 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The photolysis of trans-3,4-dimethylcyclopentanone has been investigated in the gas phase at 100°C using light of 206 and 193 nm. The photolytic products are propene, 1,2-dimethylcyclobutane, and the butene isomers. Small quantities of 3,4-dimethylpent-4-enal were also detected. Relative yields of these products were determined as a function of the ketone pressure and also of that of added nitrogen. A mechanism for the photochemical decomposition based on that suggested for the photolysis of cyclopentanone using short wavelength radiation, is consistent with the experimental results and is simpler than that required to account for the long wavelength photolysis reported earlier.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 138
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 379-397 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A laser flash photolysis-resonance fluorescence technique has been employed to study the kinetics of reactions (1)-(4) as a function of temperature. In all cases, the concentration of the excess reagent, i.e., HBr or Br2, was measured in situ in the slow flow system by UV-visible photometry. Heterogeneous dark reactions between XBr (X = H or Br) and the photolytic precursors for Cl(2P) and O(3P) (Cl2 and O3, respectively) were avoided by injecting minimal amounts of precursor into the reaction mixture immediately upstream from the reaction zone. The following Arrhenius expressions summarize our results (errors are 2σ and represent precision only, units are cm3 molecule-1 s-1): k1 = (1.76 ± 0.80) × 10-11 exp[(40 ± 100)/T]; k2 = (2.40 ± 1.25) × 10-10 exp[-(144 ± 176)/T]; k3 = (5.11 ± 2.82) × 10-12 exp[-(1450 ± 160)/T]; k4 = (2.25 ± 0.56) × 10-11 exp[-(400 ± 80)/T]. The consistency (or lack thereof) of our results with those reported in previous kinetics and dynamics studies of reactions (1)-(4) is discussed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 139
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 431-448 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction rate constants for the hydrolysis of organic esters and amides were determined at temperatures of 100-240°C in aqueous solutions buffered at pH values between 5.5 and 7.3. Experiments are modeled assuming alkaline hydrolysis with a thermodynamic solution model included to account for the temperature dependence of hydroxide ion concentration. In most cases, the ester hydrolysis second order rate constants agree well with published values from experiments in strongly basic solutions at pH values from 11 to 14 and temperatures from 25-80°C, despite the large extrapolations required to compare the data sets. The amide hydrolysis rate constants are about one order of magnitude higher than the extrapolated results from other investigators, but the reaction rate increased proportionally with hydroxide ion concentration, suggesting that an alkaline hydrolysis mechanism is also appropriate. These data establish the validity of the alkaline hydrolysis mechanism and can be used to predict hydrolysis reaction rates in neutrally-buffered solutions such as many groundwater and geothermal fluids.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 140
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 253-259 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The basis dehydrobromination of p-substituted 2-phenylethyl bromides promoted by hydroxide ion has been studied in micelles of N-hexadecyl-N,N,N-trimethylammonium nitrate (CTANO3). The pseudophase ion exchange model can be adapted to explain the kinetic results at low hydroxide ion concentration, i.e., less than 0.075 M of NaOH. At high hydroxide ion concentration in solution the applied model does not describe the kinetic results unless the empirical variations are applied for the mol ratio of reactive ion to micellar head group (β) and the binding constant of the organic reagent to the micelle (Ks).
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 141
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 399-414 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A laser flash photolysis-resonance fluorescence technique has been employed to study the kinetics of the important stratospheric reactions Cl(2PJ) + O3 → ClO + O2 and Br(2P3/2) + O3 → BrO + O2 as a function of temperature. The temperature dependence observed for the Cl(2PJ) + O3 reaction is nonArrhenius, but can be adequately described by the following two Arrhenius expressions (units are cm3 molecule-1 s-1, errors are 2σ and represent precision only): k1(T) = (1.19 ± 0.21) × 10-11 exp [(-33 ± 37)/T] for T = 189-269K and k1(T) = (2.49 ± 0.38) × 10-11 exp[(-233 ± 46)/T] for T = 269-385 K. At temperatures below 230 K, the rate coefficients determined in this study are faster than any reported previously. Incorporation of our values for k1(T) into stratospheric models would increase calculated ClO levels and decrease calculated HCl levels; hence the calculated efficiency of ClOx catalyzed ozone destruction would increase. The temperature dependence observed for the (2P3/2) + O3 reaction is adequately described by the following Arrhenius expression (units are cm3 molecule-1 s-1, errors are 2σ and represent precision only): k2(T) = (1.50 ± 0.16) × 10-1 exp[(-775 ± 30)/T] for T = 195-392 K. While not in quantitative agreement with Arrhenius parameters reported in most previous studies, our results almost exactly reproduce the average of all earlier studies and, therefore, will not affect the choice of k2(T) for use in modeling stratospheric BrOx chemistry.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 142
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 483-490 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rates of hydrolysis of hydroxamic acids with perfluorooctanoic acid as a reactive counterion surfactant and also with sodium sulfonate surfactants plus HCl have been determined in both water and aqueous acetonitrile solvents. The pseudophase ion exchange model satisfactorily explains the micellar effects for both the reactive and non-reactive counterion surfactants in both solvent systems.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 143
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990) 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 144
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 449-453 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of hydrolysis of Cu(II)-salicylamide complex have been studied in sodium hydroxide solution (0.5 to 2.5M). The observed pseudo-first-order rate constants vary according to the empirical equation 1/kobs = B1 + B2/[ŌH] up to 2.0 M sodium hydroxide concentration. The mechanism of base-catalyzed hydrolysis has been proposed and it is concluded that the reaction proceeds by the interaction of complex with the nucleophile, forming tetrahedral intermediate which then breaks down to products. The rate equation has been derived. Thermodynamic parameters have also been reported.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 145
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 491-504 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of the thermal decomposition of acetylacetone has been studied in a shock tube in the temperature range of 1120-1660 K. Detailed analyses of CO and H2O formation data indicate that H2O is formed by a four-center molecular channel, whereas CO is formed by the rapid dissociation of CH3CO produced by the C—C bond dissociation of acetylacetone. The Arrhenius equations for H2O and CH3CO formation channels are k2 = 1014.24±0.21 exp(-60,800 ± 1,220/RT)sec-1 and k3 = 1017.05±0.28 exp(-74,600 ± 1,680/RT) sec-1, respectively. The results of the study suggest that the six-center molecular channel for the production of acetone and ketene is not important under the condition used in this investigation.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 146
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 513-535 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mechanism of NH3 pyrolysis was investigated over a wide range of conditions behind reflected shock waves. Quantitative time-history measurements of the species NH and NH2 were made using narrow-linewidth laser absorption. These records were used to establish an improved model mechanism for ammonia pyrolysis. The risetime and peak concentrations of NH and NH2 in this experimental database have also been summarized graphically.Rate coefficients for several reactions which influence the NH and NH2 profiles were fitted in the temperature range 2200 K to 2800 K. The reaction and the corresponding best fit rate coefficients are as follows: \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm NH}_{\rm 2} + {\rm H} \to {\rm NH + H}_{\rm 2} $$\end{document} with a rate coefficient of 4.0 × 1013 exp(-3650/RT) cm3 mol-1 s-1, \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm NH}_{\rm 2} + {\rm NH} \to {\rm N}_{\rm 2} {\rm H}_{\rm 2} + {\rm H}$$\end{document} with a rate coefficient of 1.5 × 1015T-0.5 cm3 mol-1 s-1 and \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm NH}_{\rm 2} + {\rm NH}_{\rm 2} \to {\rm NH + NH}_{\rm 3} $$\end{document} with a rate coefficient of 5.0 × 1013 exp(-10000/RT) cm3 mol-1 s-1. The uncertainty in rate coefficient magnitude in each case is estimated to be ±50%. The temperature dependences of these rate coefficients are based on previous estimates.The experimental data from four earlier measurements of the dissociation reaction \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm NH}_{\rm 3} + {\rm M} \to {\rm NH}_{\rm 2} {\rm + H + M} $$\end{document} were reanalyzed in light of recent data for the rate of NH3 + H → NH21 + H2, and an improved rate coefficient of 2.2 × 1016 exp(-93470/RT) cm3 mol-1 s-1 in the temperature range 1740 to 3300 K was obtained. The uncertainty in the rate coefficient magnitude is estimated to be ± 15%.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 147
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 633-639 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction rates of SO3 with CH3OH in He were measured at total pressures of 0.7-1.6 torr in flow tubes. The concentration of SO3 was monitored by the SO2* fluorescence from excitation of SO3 at 147 nm. The reaction rate constant of SO3 + CH3OH in the gas phase is determined to be (1.17 ± 0.16) × 10-13 cm3 molec-1 s-1 at room temperature.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 148
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rate constants for the reactions of OH radicals and Cl atoms with diethyl sulfide (DES), di-n-propyl sulfide (DPS), and di-n-butyl sulfide (DBS) have been determined at 295 ± 3 K and a total pressure of 1 atm. Hydroxyl radical rate data was obtained using the absolute technique of pulse radiolysis combined with kinetic spectroscopy. The chlorine atom rate constants were measured using a conventional photolytic relative rate method. The rate constant for the reaction of Cl atoms with dimethyl sulfide (DMS) was also determined. The following rate constants were obtained: \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{l} k({\rm OH + DES) = (}11.6 \pm 2) \times 10^{ - 12} {\rm cm}^{\rm 3} {\rm molecule}^{{\rm - 1}} {\rm s}^{{\rm - 1}} \\ k({\rm OH + DPS) = (}21.5 \pm 3) \times 10^{ - 12} {\rm cm}^{\rm 3} {\rm molecule}^{{\rm - 1}} {\rm s}^{{\rm - 1}} \\ k({\rm OH + DBS) = (}37.4 \pm 5) \times 10^{ - 12} {\rm cm}^{\rm 3} {\rm molecule}^{{\rm - 1}} {\rm s}^{{\rm - 1}} \\ k({\rm Cl + DMS) = (}32.2 \pm 3) \times 10^{ - 11} {\rm cm}^{\rm 3} {\rm molecule}^{{\rm - 1}} {\rm s}^{{\rm - 1}} \\ k({\rm Cl + DES) = (}44.1 \pm 4) \times 10^{ - 11} {\rm cm}^{\rm 3} {\rm molecule}^{{\rm - 1}} {\rm s}^{{\rm - 1}} \\ k({\rm Cl + DPS) = (}51.8 \pm 4) \times 10^{ - 11} {\rm cm}^{\rm 3} {\rm molecule}^{{\rm - 1}} {\rm s}^{{\rm - 1}} \\ k({\rm Cl + DBS) = (}64.6 \pm 2) \times 10^{ - 11} {\rm cm}^{\rm 3} {\rm molecule}^{{\rm - 1}} {\rm s}^{{\rm - 1}} \\ \end{array} $$\end{document}
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 149
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 665-671 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The relative rate technique has been used to measure rate constants for the reaction of chlorine atoms with nitro methane, nitro ethane, nitro propane, nitro butane, nitro pentane, ethyl nitrate, isopropyl nitrate, n-propyl nitrate, 2-pentyl nitrate, and 2-heptyl nitrate. Decay rates of these organic species were measured relative to one or more of the following reference compounds; n-butane, ethane, chloroethane, and methane. Using rate constants of 2.25 × 10-10 5.7 × 10-11, 8.04 × 10-12, and 1.0 × 10-13 cm3 molecule-1 s-1 for the reaction of Cl atoms with n-butane, ethane, chloroethane, and methane, respectively, the following rate constants were derived, in units of cm3 molecule-1 s-1: nitro methane, 〈7 × 10-15; nitro ethane, (2.05 ± 0.14) × 10-13; nitro propane, (1.13 ± 0.05) × 10-11; nitro butane, (5.13 ± 0.68) × 10-11; nitro pentane, (1.40 ± 0.14) × 10-10; ethyl nitrate, (3.70 ± 0.24) × 10-12; n-propyl nitrate, (2.15 ± 0.13) × 10-11; i-propyl nitrate, (3.94 ± 0.48) × 10-12; 2-pentyl nitrate, (1.00 ± 0.06) × 10-10; and 2-heptyl nitrate, (2.84 ± 0.50) × 10-10. Quoted errors represent 2σ and do not include possible systematic errors due to errors in the reference rate constants. Experiments were performed at 295 ± 2 K and atmospheric pressure (≃740 torr) of synthetic air. The results are discussed with respect to the previous literature data and to the modeling of these compounds in the atmosphere.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 150
    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 reCedex 2, Franceactions of O(3P) atoms with a series of symmetric aliphatic ethers have been determined using the flash photolysis resonance fluorescence technique over the temperature range 240-400 K. The Arrhenius parameters derived from these data are (in units of cm3 molecule -1 s-1): \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{rcl} {\rm dimethyl ether,}k &=& (5.39 \pm 1.94) \times 10^{ - 12} {\rm exp[(} - {\rm 1320} \pm 120)/T]; \\ {\rm diethyl ether,}k &=& (1.42 \pm 0.18) \times 10^{ - 11} {\rm exp[(} - {\rm 1070} \pm 40)/T]; \\ {\rm di -}n{\rm - propyle ether,}k &=& (1.41 \pm 0.21) \times 10^{ - 11} {\rm exp[(} - {\rm 960} \pm 50)/T]; \\ {\rm di -}n{\rm - butyl ether,}k &=& (1.37 \pm 0.29) \times 10^{ - 11} {\rm exp[(} - {\rm 880} \pm 70)/T]; \\ {\rm di -}n{\rm - pentyl ether,}k &=& (1.26 \pm 0.84) \times 10^{ - 11} {\rm exp[(} - {\rm 780} \pm 200)/T]; \\ \end{array} $$\end{document}The error limits are two standard deviations derived from the least-squares fit. Rate constants for several other ethers were determined only at 298 K. The values obtained were (in units of 10-14 cm3 molecule-1 s-1): tetrahydrofuran (37.5 ± 1.1); 1,4-dioxane 1(6.81 ± 0.46); diethoxymethane (40.4 ± 1.8); ethyl -t-butyl ether (37.0 ± 1.3); and methyl-t-amylether (57.3 ± 2.3).
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 151
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 905-914 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The stability of some Schiff-bases formed between PLP and different amino acids has been investigated in a wide range of pH. The kinetic constants of formation of these compounds and their hydrolysis rate constants have been determined. Results show that the α-position of the carboxyl group of amino acid plays an important role on the mechanism of water attack upon the C=N—bond. The absence of ionic groups in the surroundings of that bond must be an important factor of stability. Bulky hydrophobic substituents in the amino acid, near the amine part, protect the imine bond against hydrolysis.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 152
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 999-1014 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics and nitroarene product yields of the gas-phase reactions of naphthalene-d8, fluoranthene-d10, and pyrene with OH radicals in the presence of NOx and in N2O5—NO3—NO2—air mixtures have been investigated at 296 ± 2 K and atmospheric pressure of air. Using a relative rate method, naphthalene-d8 was shown to react in N2O5—NO3—NO2—air mixtures a factor of 1.22 ± 0.10 times faster than did naphthalene, with the 1- and 2-nitronaphthalene-d7 product yields being similar to those of 1- and 2-nitronaphthalene from naphthalene. From the measured PAH concentrations and the nitroarene product yields, formation yields of 2-, 7-, and 8-nitrofluoranthene-d9 and 2- and 4-nitropyrene of 0.03, 0.01, 0.003, 0.005, and 0.0006, respectively, were determined from the OH radical-initiated reactions. Effective rate constants for the reactions of fluoranthene-d10 and pyrene with N2O5 in N2O5—;NO3—NO2—air mixtures of ca. 1.8 × 10-17 cm3 molecule-1 s-1 and ca. 5.6 × 10-17 cm3 molecule-1 s-1, respectively, were derived. Formation yields of 2-nitrofluoranthene-d9 and 4-nitropyrene of ca. 0.24 and ca. 0.0006, respectively, were estimated for these reaction systems. 2-Nitropyrene was also observed to be formed in these N2O5—NO3—NO2 reactions, but was found to be a function of the NO2 concentration and, therefore, would be a negligible product under ambient NO2 concentrations. These product and kinetic data are consistent with ambient air measurements of the nitroarene concentrations.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 153
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 791-813 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Molecular modulation spectroscopy combined with ultraviolet spectroscopic techniques have been used to observe the behavior of the CH3O2 radicals generated in the gas phase by near-ultraviolet modulated photolysis of flowing Cl2—CH4—O2 mixtures. The kinetics of the disproportionation reaction (1) and the absorption cross-sections of CH3O2 were measured by computer fitting of the modulated absorption traces obtained in the wavelength range 220 to 270 nm at 300 K and 240 torr. The rate constant for the elementary self-reaction k1 = k1(a) + k1(b) + k1(c) was determined to be (3.61 ± 0.55) × 10-13 cm3 molecule-1 s-1. The parameter kobs/σ (where kobs is the observed apparent second-order rate constant) was measured from the decay curves in the dark phase of the modulated photolysis period in the wavelength range 230-260 nm, and had a value 1.16 × 105 cm2 s-1 at 250 nm. At 250 nm the absorption cross-section was determined as σ(CH3O2) = 4.14 × 10-18 cm2 molecule-1, leading to a value of kobs, = (4.8 ± 0.5) × 10 13 cm3 molecule-1 s-1. In addition, the absorption spectrum of CH3O2 was measured in the range 210-295 nm using diode array spectroscopy. A detailed review of all previous studies concerning the kinetics and spectrum of the CH3O2 radical is presented, and a recommended spectrum, representing an average from selected recent studies, is proposed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 154
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990) 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 155
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 113-133 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An aged kineticist was awakened in 1989 from a 50-year slumber. After arduous study he sized-up the present situation, with occasional reflections on the state of knowledge in 1939.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 156
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990) 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 157
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990) 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 158
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 351-358 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The absolute second-order rate coefficient for the reaction, O(3P) + CH3OOH → products, was measured to be k1 = (1.06 ± 0.26) × 10-14 cm3 molec-1 s-1 at 297 K, where the quoted error is 2σ including precision and estimated systematic errors. The possible presence of (CH3CH2)2O in our sample of CH3OOH leads to a large error in k1 which reflects the relatively large uncertainty indicated. O(3P) was generated in excess CH3OOH by photolyzing a small amount of O3 at 532 nm, where CH3OOH does not photolyze. The rate of removal of O(3P) in the experiments was monitored by resonance fluorescence detection. The increased reactivity of O(3P) with CH3OOH relative to H2O2 is interpreted as due to H abstraction from the CH3 group.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 159
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990) 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 160
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 577-590 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction mechanisms for oxidation of CH3CCl2 and CCl3CH2 radicals, formed in the atmospheric degradation of CH3CCl3 have been elucidated. The primary oxidation products from these radicals are CH3CClO and CCl3CHO, respectively. Absolute rate constants for the reaction of hydroxyl radicals with CH3CCl3 have been measured in 1 atm of Argon at 359, 376, and 402 K using pulse radiolysis combined with UV kinetic spectroscopy giving k(OH + CH3CCl3) = (5.4 ± 3) 10-12 exp(-3570 ± 890/RT) cm3 molecule-1 s-1. A value of this rate constant of 1.3 × 10-14 cm3 molecule-1 s-1 at 298 K was calculated using this Arrhenius expression. A relative rate technique was utilized to provide rate data for the OH + CH3 CCl3 reaction as well as the reaction of OH with the primary oxidation products. Values of the relative rate constants at 298 K are: k(OH + CH3CCl3) = (1.09 ± 0.35) × 10-14, k(OH + CH3CClO) = (0.91 ± 0.32) × 10-14, k(OH + CCl3CHO) = (178 ± 31) × 10-14, k(OH + CCl2O) 〈 0.1 × 10-14; all in units of cm3 molecule-1 s-1. The effect of chlorine substitution on the reactivity of organic compounds towards OH radicals is discussed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 161
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990) 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 162
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 719-740 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hydrogen peroxide formation in the photooxidation of CO—NOx, ethene—NOx, and propene—NOx mixtures has been determined in the TVA 31 cubic meter smog chamber under the following conditions: [NOx] ca. 22-46 ppb; ethene = 0.22-1.1 ppm, [propene] = 0.12-0.97 ppm; [H2O] ca. 8 × 10-3 ppm. Ethene, propene, NO, NOx, PAN, HCHO, and CH3CHO were also monitored. Computer modeling was performed using the gas phase ethene and propene mechanism of the Regional Acid Deposition Model. There is good agreement between the model predicted and observed H2O2 concentrations. However, to successfully model all the propene—NOx experimental results, organic nitrate formation from the reaction of peroxy radicals with NO must be included in the mechanism.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 163
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990) 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 164
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 815-827 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A treatment of ionic-atmosphere effects upon symmetrical electron-transfer reactions resulting from added electrolyte is outlined. Relationships are derived on the basis of the extended Debye-Huckel model for the increase in the activation free energy, ΔGia*, associated with reorganization of the ionic atmosphere for homogeneous-phase reactions involving a pair of spherical reactants with varying internuclear distance R. Similar relationships apply to the energetics of symmetrical optical electron transfer, since the increase in the optical transition energy, ΔEopia, should equal the corresponding ionic atmosphere reorganization energy, Eria; under the anticipated linear response conditions, Eria = 4ΔGia*. The predicted ΔGia* (and hence ΔEopia) values increase sharply with increasing R, as a consequence of the diminished “sharing” of the ionic cloud surrounding the donor and acceptor sites under these conditions. Outer-sphere electrochemical reactions, featuring a single “near-isolated” reactant, are predicted to feature substantially larger ΔGia* values than for homogeneous processes proceeding with the reaction partners in contact. The influence of more specific “ionic atmosphere” effects upon ΔGia*, especially involving reactant-electrolyte ion pairing, is also discussed. Unlike that of the nonspecific ionic atmosphere, the nuclear reorganization process associated with counterion transport between donor and acceptor sites coupled with electron transfer is nonlinear in nature, so that Eria ≠ 4ΔGia*. Some recent experimental data for electrolyte effects upon the rate constants for ferrocenium-ferrocene self exchange and related systems are examined in the light of these considerations.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 165
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 871-887 
    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 O3 with a series of monoterpenes and related compounds have been determined at 296 ± 2 K and 740 torr total pressure of air or O2 using a combination of absolute and relative rate techniques. Good agreement between the absolute and relative rate data was observed, and the rate constants obtained (in units of 10-17 cm3 molecule-1 s-1) were: α-pinene, 8.7; β-pinene, 1.5; Δ3-carene, 3.8; 2-carene, 24; sabinene, 8.8; d-limonene, 21; γ-terpinene, 14; terpinolene, 140; α-phellandrene, 190; α-terpinene, 870; myrcene, 49; trans-ocimene, 56; p-cymene, 〈0.005; and 1,8-cineole, 〈0.015. While these rate constants for α- and β-pinene and sabinene are in good agreement with recent absolute and relative rate determinations, those for the other monoterpenes are generally lower than the literature data by factors of ca. 2-10. The measured rate constants for the monoterpenes are reasonably consistent with predictions based upon the number and positions of the substituent groups around the 〉C=C〈 bond(s).
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 166
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 975-980 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No Abstract Found.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 167
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990) 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 168
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 21-35 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Measurements rate constants for abstraction of hydrogen from ethylene by methyl and ethyl radicals relative to the corresponding rate constants for abstraction from hydrogen, over the temperature range 650-770 K, are reported. The methodis based on the effect of the addition of small quantities of hydrogen on the rates of formation of methane and ethane in the thermalchain reactions of ethylene. On the assumption that methane and ethane are formed by the following reactions: measurements of the relative rates of formation of methane and ethane in the presence and absence of hydrogen gave the following ratios of rate constants: (R = 8.314 Joule mol-1 K-1) \documentclass{article}\pagestyle{empty}\begin{document}$$\begin{array}{l} {\rm log(}k_1 /k_2) = 1.3 \pm 0.15 + 4000 \pm 2000/2.3RT \\ {\rm log(}k_3 /k_4) = 1.6 \pm 0.15 - 0 \pm 2000/2.3RT \end{array}$$\end{document} With values from the literature for k1 and k3 the following values were obtained for k2 and k4: \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{l} {\rm log}k_2 {\rm (}L{\rm mol}^{{\rm - 1}} {\rm s}^{{\rm - 1}}) = 8.7 \pm 0.2 - 63000 \pm 3000/2.3RT \\ {\rm log}k_4 {\rm (}L{\rm mol}^{{\rm - 1}} {\rm s}^{{\rm - 1}}) = 8.2 \pm 0.2 - 62200 \pm 3000/2.3RT \\ \end{array} $$\end{document}
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 169
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 81-94 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of oxidation of cyclohexanone(chxn), 2-butanone(but), and 1,3-dihydroxy-2-propanone (dhp) have been investigated in aqueous acidic media. A first-order dependence in complex is obtained at high acid and low oxidant concentration for these ketones. However, a zero-order rate prevails at high oxidant and low acid concentration, and this rate has been shown to be the acid catalyzed enolization rate of the ketone. A general rate expression has been derived to explain these behaviors and plausible mechanism has been offered by assuming the enol as the reactive species.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 170
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 103-111 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of cationic and anionic surfactants on the reaction of Basic Blue 3 (2,7-bis(diethylamino)phenazoxonium chloride, 1) with hydroxide ion has been studied. Cetyltrimethylammonium bromide (CTAB), cetyl and tetradecyltrimethylammonium chloride (CTAC and MTAC) enhance the rate of basic hydrolysis whereas sodium dodecyl sulfate (SDS) has an inhibitory effect. The extent of micellar catalysis is reduced by the addition of organic solvents. The results have been analyzed on the basis of the pseudophase ion-exchange model [1-3].
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 171
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 187-206 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A detailed master equation simulation has been carried out for the thermal unimolecular decomposition of C6H10 in a shock tube. At the highest temperatures studied experimentally [J. H. Kiefer and J. N. Shah, J. Phys. Chem., 91, 3024 (1987)], the average thermal vibrational energy is greater than the reaction threshold and therefore 〈ΔE〉 (up and down steps) is positive for molecules at that energy, rather than negative; the converse is true at lower temperatures. The calculated incubation time, in which the decomposition rate constant rises to 1/e of its steady state value, is found to be only weakly dependent on temperature (at constant pressure) between 1500 K and 2000 K and to depend almost exclusively on 〈ΔE〉d (down steps, only), and not on collision probability model. Simulations of the experimental data show the magnitude of 〈ΔE〉d depends weakly on assumed collision probability model, but is nearly independent of temperature. The second moment 〈ΔE〉½ is found to be independent of both temperature and transition probability model. The experimental data are not very sensitive to the possible energy-dependence of 〈ΔE〉d for a wide range of assumptions. It is concluded that the observed experimental “delay times” probably can be identified with the incubation time; further experiments are desirable to test this possibility and obtain more direct measures of the incubation time.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 172
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 219-241 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A single kinetic mechanism for methanol pyrolysis is tested against multiple sets of experimental data for the first time. Data are considered from static, flow, and shock tube reactors, covering temperatures of 973 to 2000 K and pressures of 0.3 to 1 atmosphere. The model results are highly sensitive to the rates of unimolecular fuel decomposition and of various chain termination reactions that remove CH2OH and H radicals, as well as to experimental temperature uncertainties. The secondary fuel decomposition reaction CH3OH = CH2OH + H, which has previously been included only in mechanisms for high temperature conditions, is found to have a significant effect at low temperatures as well, through radical recombination. The reaction CH3O + C = CH3 + CO2, rather than CH3OH + H = CH3 + H2O, is found to be the dominant source of CH3 at low temperatures. The reverse of CH3 + OH = CH2OH + H is important to CH3 production at high temperatures.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 173
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The solvolysis of cis(chloro)(1-amino-propan-2-ol)bis(ethylenediamine)cobalt(III) in aqueous alcoholic media using methanol, propan-2-ol, t-butanol as cosolvents, resulted in the formation of the (N,O) chelated productcis[Co(en)2(NH2CH2CHOHCH3)]3+. The pseudo first order rate constant decreased with increasing molfraction (Xorg) of alcohols, the decrease being less marked as the bulkiness of hydrophobic moiety of alcohol increased. The plots of log kobs vs. reciprocal of the bulk dielectric constant of the solvents, log kobs vs. Grunwald-Winstein solvent parameter and log kobs, vs. Xobs under isodielectric condition (Ds = 50, at 50°C) for CH3OH/H2O, C2H5OH/H2O, (CH3)2CHOH/H2O, (CH3)3C—OH/H2O, (CH2)2(OH)2/H2O, and (CH3)2 C = O/H2O in water rich media indicated that both solvent structural effects and presumably the hydrophobic interaction appreciably mediate the reaction. The calculated values of the relative transfer free energy at 25°C[ΔGt(C3-)-ΔGt(i.s)(s←w)] where C3+ and i.s. denote the dissociative transition state {cis[Co(en)2(NH2CH2CHOHCH3)]3+}* and the initial state, respectively, indicated that the tripositive transition state is more effectively solvated by the mixed solvent media, than the dipositive initial state, the effect appeared to be more significant with increasing Xorg. The plots of activation enthalpy and entropy against Xorg exhibited maxima and minima indicating that enthalpy and entropy changes associated with the solvent shell reorganization of the reactant contribute to the overall activation parameters.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 174
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 359-378 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title reaction was studied in a discharge flow system using mass flow and modulated molecular beam sampling with phase-sensitive detection in order to obtain time-resolved mass spectrometric analysis. At total conversion exceeding 30%, the major products are methane and ethane when initially hydrogen atoms are in excess; when butene is in excess, the major products are ethane and propylene. No hydrocarbons with more than 4 carbon atoms were detected in the products. The reaction is a complicated one since the simplest reaction scheme that successfully simulates the experimental results comprises 20 elementary reactions. The simulation, coupled with sensitivity analysis, shows that with hydrogen atoms in excess, significant amounts of propylene formed in the initial decomposition of the butyl radical react further with hydrogen atoms to form methane and ethane. When butene is in excess, approximately [C3H6] ≈ [CH4] + ½[C2H6] which means that this propylene does not react further and almost all methyl radicals end up as CH4 or C2H6. At small conversion, simulation shows that the major product by far is propylene regardless of the [H]/[butene] ratio. The absence of higher hydrocarbons in the products is at variance with earlier results of Rabinovitch and coworkers; however the present work leads to a comparable value for the average rate constant ka = ωD/S where D and S is the amount of products arising from the decomposition and stabilization, respectively, of the butyl radical and ω is the collision frequency.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 175
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 415-426 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of chlorination of a number of ortho-, meta-, and para-substituted phenols by N-chloro-3-methyl-2,6-diphenylpiperidin-4-one (NCP) in acid medium have been investigated. The reaction is of first order with respect to oxidant and the order with respect to the substrate varies depending on the nature of the substituent present in the ring. With cresols and m-chlorophenol the order is unity, with p-methoxyphenol, zero and with the other phenols, a fraction. Isokinetic and Exner plots give straight lines with fine correlation coefficients. But the Hammett plot gives a curve that was concave downwards, instead of a straight line. The observed Hammett plot deviation has been accounted for suitably. Regression analyses of the rate data of ortho-substituted phenols by using Taft and Charton equations to separate steric effects from electronic effects have been carried out. In this reaction, the localized electronic effect plays a major role while steric and resonance effects play a minor role.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 176
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of CH2O with NO2 has been studied with a shock tube equipped with two stabilized ew CO lasers. The production of CO, NO, and H2O has been monitored with the CO lasers in the temperature range of 1140-1650 K using three different Ar-diluted CH2O-NO2 mixtures. Kinetic modeling and sensitivity analysis of the observed CO, NO, and H2O production profiles over the entire range of reaction conditions employed indicate that the bimolecular metathetical reaction, NO2 + CH2O → HONO + CHO (1) affects most strongly the yields of these products. Combination of the kinetically modeled values of k1 with those obtained recently from a low temperature pyrolytic study, ref. [8], leads to \documentclass{article}\pagestyle{empty}\begin{document}$$ k_1 = 8.02 \times 10^2 T^{2.77} e^{ - 6910/T} {\rm cm}^{\rm 3} /{\rm mol sec} $$\end{document} for the broad temperature range of 300-2000 K.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 177
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 537-541 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rate constant for abstraction of hydrogen from isobutane by methyl radicals has been re-examined making use of new measurements at temperatures above 660 K. Most of the data over the temperature range 300-855 K can be accommodated by the following values for the rate constants for abstraction from primary and tertiary hydrogen atoms: \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm log}k_{4T} ({\rm L mol}^{{\rm - 1}} {\rm s}^{{\rm - 1}}) = 8.15 - \frac{{33800}}{{2.3RT}}\quad (R = 8.314{\rm J mol}^{{\rm - 1}} {\rm K}^{{\rm - 1}}) $$\enddocument} \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm log}k_{4P} ({\rm L mol}^{{\rm - 1}} {\rm s}^{{\rm - 1}}) = 8.88 - \frac{{48400}}{{2.3RT}}$$\enddocument} This activation energy for abstraction of the tertiary hydrogen atom in isobutane is essentially the same as expressed in a previous evaluation, which considered data only below 500 K, but the magnitude of the rate constant is about 0.25 log units greater.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 178
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 591-602 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The gas-phase reaction of methacrolein with the OH radical, in the presence of NOx, was investigated at 298 ± 2 K and atmospheric pressure of air. Hydroxyacetone, methylglyoxal, a peroxyacyl nitrate identified as CH2 = C(CH3)C(O)OONO2 (peroxymethacryloyl nitrate), formaldehyde, CO, and CO2 were observed to be the major products. The product yield data for these compounds show that OH radical addition to the 〉C = C〈 bond accounts for ca. 50% of the overall reaction, with the remaining ca. 50% proceeding via H - atom abstraction from the —CHO group. The data suggest that the alkoxy radical formed following the addition of OH to the terminal carbon atom, decomposes primarily to give the formyl radical plus hydroxyacetone. A lower limit ratio of 5: 1 has been estimated for OH radical addition to the terminal carbon atom of the double bond relative to addition on the inner carbon atom.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 179
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 641-664 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ethylene oxidation and pyrolysis was modeled using a comprehensive kinetic reaction mechanism. This mechanism is an updated version of one developed earlier. It includes the most recent findings concerning the kinetics of the reactions involved in the oxidation of ethylene. The proposed mechanism was tested against ethylene oxidation experimental data (molecular species concentration profiles) obtained in jet stirred reactors (1-10 atm, 880-1253 K), ignition delay times measured in shock tubes (0.2-12 atm, 1058-2200 K) and ethylene pyrolysis data in shock tube (2-6 atm, 1700-2200 K). The general prediction of concentration profiles of minor species formed during ethylene oxidation is improved in the present model by using more accurate kinetic data for several reactions (principally: HO2 + HO2 → H2O2 + O2, C2H4 + OH → C2H3 + H2O, C2H2 + OH → Products, C2H3 → C2H2 + H).
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 180
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 683-688 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The initial rate of any general nth order (n not necessarily integer) chemical reaction can be accurately and easily computed from the slope of a chord joining two points on the progress curve. Expressions for calculating the intermediate concentration corresponding to this initial rate are provided. Examples of the technique applied to second- and third-order reactions as well as an example of a reaction with fractional order (n = 0.6) are given.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 181
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The pyrolysis of 2% CH4 and 5% CH4 diluted with Ar was studied using both a single-pulse and time-resolved spectroscopic methods over the temperature range 1400-2200 K and pressure range 2.3-3.7 atm. The rate constant expressions for dissociative recombination reactions of methyl radicals, CH3 + CH3 → C2H5 + H and CH3 + CH3 → C2H4 + H2, and for C3H4 formation reaction were investigated. The simulation results required considerably lower value than that reported for CH3 + CH3 → C2H4 + H2. Propyne formation was interpreted well by reaction C2H2 + CH3 → P-C3H4 + H with k = 6.2 × 1012 exp(-17 kcal/RT) cm3 mol-1 s-1.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 182
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 786-786 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 183
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 843-861 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mixtures of NO and NO/H2 in Ar were shock-heated and photolyzed with an ArF excimer laser. Measurements in these experiments of N-atom profiles using atomic resonance absorption spectrophotometry (ARAS) permitted the determination of two rate coefficients. The rate coefficient for the reaction was found to be 4.29 × 1013 exp(-787/T) cm3 mol-1 sec-1 (±20% at 1400 K to ±10% at 3500 K). This is the first direct high temperature measurement of this rate coefficient in the exothermic direction. The rate coefficient for the reaction was found to be 1.60 × 1014 exp(-12650/T) (±35% from 1950 to 2850 K). To our knowledge, this is the first direct measurement of this rate coefficient.A study of the N-atom ARAS absorption behavior revealed a noticeable pressure dependence, as well as a weak temperature dependence, in the Beer-Lambert law absorption coefficient. Proper consideration of these effects is important when the N-atom ARAS diagnostic is used for absolute concentration measurements.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 184
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 863-869 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of the oxidation of water with bismuth(V) in presence of silver(I) has been investigated in a mixture of HClO4 (1.0 mol dm-3) and HF (1.5 mol dm-3). The reaction is second order, viz., first order with respect to bismuth(V) and silver(I), each, and the second order rate constant is (6.6 ± 0.7) × 10-3 dm3 mol-1 s-1. However, rate is independent of hydrogen ion concentration. A comparative analysis of these results with the results obtained for pdp, pds, and Ce(IV), reactions with silver(I) has also been made to correlate the rate constants and the redox-potentials of the oxidant couples.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 185
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 915-934 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Recent experimental results on the thermal decomposition and the reverse recombination of alkyl and haloalkyl peroxynitrates are modelled with an SACM formalism. The molecules RO2NO2 with R = CH3, CF3, CF2Cl, CFCl2, CCl3, and C2H5 are considered. Detailed and simplified reduced falloff expressions are compared. Limiting low (ko) and high pressure (kx) rate constants, such as derived from a fit of these falloff expressions to the experiments, are compared with absolute predictions, based on general knowledge about energy transfer (〈ΔE〉 in ko) and on a recently proposed simple SACM estimate for kx. The analysis also allows for a derivation of the bond energies of the mentioned molecules.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 186
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 951-961 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In lowest approximation, a certain chemical reaction is described by a system of first-order linear differential equations with unknown constant coefficients. One can therefore write down an expression for the state of the system at time t, and from this find the endpoint of the reaction in terms of the initial state and the rate constants. The relative values of some rate constants can then be estimated from experimental data.A better approximation in which the differential equations are nonlinear is also considered, and it turns out that because of symmetry in the reaction, the relationship between the final state and the ratios of the rate constants is unchanged. Although the differential equations now appear much less tractable, the problem of relating the rate constants to the endpoint of the reaction can be formulated and solved in terms of probabilities.The results illustrate an important property of reaction schemes in which some of the steps are reversible. More generally, this is a property of differential equations: provided that they continue to satisfy certain linear constraints, the parameters of a linear system of ordinary differential equations can vary without affecting the asymptotic solution.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 187
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 1-19 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This article is concerned with the Stern-Volmer dependence on the NO2, SO2, and CS2fluorescence self-quenching within a wide range of pressure variations of these gases. Besides, the pressure-dependences of the photolysis rate of these substances have been investigated. The deviations from linearity in the Stern-Volmer dependences and photolysis rate of NO2, SO2, and CS2in the highpressure region have been revealed. These deviations correspond to increasing effective rate constant of the collision quenching ofexcited molecules NO2, SO2, and CS2.A model to describe the deviations observed has been proposed. The model assumes the formation of excimer particles which may dissociate in a monomolecular way and may be quenched at collisions. The estimates of the lifetimes of excimer particles yield the values of the order of several nanoseconds.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 188
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 59-67 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using a relative rate technique, rate constants for the gas-phase reactions of the OH radical with the three cresols and the six dimethylphenols have been determined at 296 ± 2 K and atmospheric pressure. The rate constants for the cresols, which range from 4.3 × 10-11 cm3molecule-1 s-1to 6.8 × 10-11 cm3molecule-1 s-1, are in good agreement with previous literature data. The rate constants for 2,3-, 2,4-, 2,5-, 2,6-, and 3,4-dimethylphenol are all in the range (6.6-8.1) × 10-11 cm3 molecule-1 s-1, with the rate constant for 3,5-dimethylphenol being somewhat higher at 1.13 × 10-10 cm3 molecule-1 s-1. Rate constants estimated from the number, identity, and positions of the substituent groups around the aromatic ring agree to within a factor of approximately 2 with these experimentally determined rate constants.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 189
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 95-97 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 190
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The pyrolysis products formed during the isothermal decomposition of HMX at 211°C are H2O, HCN, CO, CH2O, NO, N2O, methylformamide, C2H6N2O, octahydro-1-nitroso-3,5,7-trinitro-1,3,5,7-tetrazocine, and a nonvolatile residue. The temporal behaviors of these products during the decomposition are presented. The method for using time-of-flight (TOF) velocity spectra to assist mass-spectrometry measurements in identifying the different gaseous products formed from the pyrolysis of a material by determining the approximate molecular weights of the different gaseous products contributing to the different m/z values in the mass spectrum of the mixture is described. The ion fragmentation of HMX as a function of electron energy shows complete fragmentation of the HMX molecular ion for electron energies ≥ 12.4 eV. No fragments from the pyrolysis of HMX other than those mentioned above are observed.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 191
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 211-217 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of the gas phase elimination of 2-bromo-2-butene were determined in a static system over the temperature range of 340-380°C and pressure range of 37-134 torr. The reaction in seasoned vessels, even in the presence of a free radical inhibitor, is catalyzed by hydrogen bromide. Under maximum catalysis of HBr, the kinetics were found to be of order 1.0. The reaction, when maximally catalyzed with HBr, appears to undergo a molecular elimination of HBr which follows first-order kinetics. The products are 1,2-butadiene and hydrogen bromide. The rate coefficients. under maximum catalysis, are given by the Arrhenius equation log k1(s-1) = (13.57 ± 0.56) - (200.4 ± 6.8) kJ mol-1 (2.303RT)-1. The catalyzed pyrolysis of 2-bromo-2-butene appears to proceed through a six-membered cyclic transition-state type of mechanism.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 192
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 261-287 
    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 has been studied. The results indicate that this reaction is autocatalyzed by both manganese(II) ion (formed as a reaction product) and colloidal manganese dioxide (formed as an intermediate). The apparent rate constants corresponding to the noncatalytic and autocatalytic reaction pathways are given, respectively, by the following equations \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{l} k_1 = (k_1^{bc} /[{\rm H}^{\rm +}] + k_1^{nc} + k_1^{ac} [{\rm H}^{\rm +}]^3)[{\rm HCOOH]} \\ k_2 = (k_2^{bc} /[{\rm H}^{\rm +}] + k_2^{nc} + k_2^{ac} [{\rm H}^{\rm +}]^3)[{\rm HCOOH]} \\ \end{array} $$\end{document} The activation energies associated with the true rate constants, k1bc, k1nc, k1ac, k2bc, k2nc, and k2ac are 37.2, 62.5, 70.9, 52.5, 40.8, and 59.9 kJ mol-1, respectively. The percentage of the total reaction corresponding to each pathway is given for typical experimental conditions. Mechanisms in agreement with the kinetic data are proposed for the six different reaction pathways observed.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 193
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 299-305 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to compare the catalytic activity of bromine with those of iodine and iodine monohalides, kinetic studies on the reaction, Et3SiOBun + BusOH ⇌ Et3SiOBus + BunOH, were undertaken. Pseudo first-order rate constants were determined at 0°, 10°, 15°, 20°, and 30°C by means of gas chromatography on the reaction mixtures containing both butanols in excess. From the observed rate constants, the catalytic coefficients of bromine were evaluated as follows: \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{l} k_{2_{{\rm Br}_{\rm 2}}} = 6.6 \times 10^7 {\rm exp}(- 44.5 \times 10^3 /RT); \\ k_{ - 2_{{\rm Br}_{\rm 2}}} = 8.1 \times 10^7 {\rm exp}(- 43.0 \times 10^3 /RT). \\ \end{array} $$\end{document}The enthalpies and entropies of activation were estimated to be (42.0 - 42.2) kJ/mol, -(103 - 104) J/K (forward reaction), and (40.4 - 40.7) kJ/mol, - (101 - 102) J/K (reverse reactions). These data suggest that bromine is much more active than iodine and iodine monohalides, and its high activity was interpreted on the basis of the structure of the reaction intermediate.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 194
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 289-297 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of the recombination reaction corresponding to the FSO3 + FSO3 ⇔ F2S2O6 equilibrium system has been studied. A time-resolved absorption spectroscopy technique was employed to monitor the appearance of thermally generated FSO3 radicals at 450 nm following a small temperature jump induced after partial laser photodissociation of F2S2O6 at 193 rim. The recombination rate constants have been determined over the temperature range 415-525 K and a N2 pressure range 10-600 torr. The reaction was found to be in its first order regime. The resulting limiting high pressure rate constants were combined with previous values measured in this laboratory at lower temperatures yielding the expression krec, x = (4.5 ± 0.2) × 10-14 (T/300)(1.0 ± 0.1) cm3 molecule-1 s-1 between 293 and 525 K. The temperature coefficient of krec, x is smaller than the one derived from steady-state experiments of the thermal dissociation of F2S2O6 and the equilibrium constant of the system. A recently formulated version of the canonical statistical adiabatic channel model was used to interprete the rate constants.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 195
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 331-349 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The oxidation of serine (HORCO2H) by acid permanganate was investigated both in the absence and presence of sodium dodecyl sulfate (SDS). It has been observed that the presence of surfactant enhanced the reaction rate. The reaction is first order with respect to [Serine] and [MnO4-]. The reaction is retarded by the hydrogen ion in the absence of SDS but catalyzed in the presence of SDS. The overall rate expression for the reduction of Mn(VII) may be written as \documentclass{article}\pagestyle{empty}\begin{document}$$ - \frac{{d[{\rm Mn(VII)}]_{{\rm total}}}}{{dt}} = \{ k'_{4f} + k'_{2f} /[{\rm H}^{\rm +}]\} [{\rm Serine]}_{\rm 0} [{\rm Mn(VII)]}_{{\rm total}}. $$\end{document} In the presence of SDS of the rate law is \documentclass{article}\pagestyle{empty}\begin{document}$$- \frac{{d[{\rm Mn(VII)}]_{{\rm total}}}}{{dt}} = \{ k[{\rm H}^{\rm +}] + k'\} [{\rm SDS}][{\rm Serine]}_{\rm 0} [{\rm Mn(VII)]}_{{\rm total}}. $$\end{document} The reaction appears to involve a parallel consecutive reaction mechanism in which Mn(IV) appears as the reaction intermediate. k′4f signifies the rate constant for the reaction path leading to the formation of Mn(IV) from Mn(VII) as reaction intermediate, whereas k′2f signifies the rate constant for the reaction path leading to the reduction of Mn(VII) to Mn(II) without prior formation of Mn(IV). A mechanism satisfying the various kinetic parameters has been proposed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 196
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990) 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 197
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 505-512 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rate constants have been measured by pulse radiolysis for the reactions of the NO3 radical with five cyclic ethers and a series of alcohols. Rate constants ranged from 3.5 × 104 M×1 s×1 for deuterated methanol to 1.1 × 107 M-1 s-1 for tetrahydrofuran. The rate constants for the reactions of NO3 with the alcohols 1-propanol to 1-heptanol were found to be linearly dependent on the number of CH3 groups with a group reactivity of 6.4 × 105 M-1 s-1.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 198
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 547-575 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Data from several smog chamber reaction vessels have been analyzed in an attempt to elucidate the chemical species which are responsible for chamber specific background phenomena, and the nature of the processes which determine the heterogeneous interactions of those species. There is good evidence for the emission of a compound which yields both NOx, and free radicals (probably HONO) and emissions of reactive organics (e.g. HCHO) may also be deduced. Total integrated chamber emission of these compounds may be as high as 20 to 60 ppb during a typical smog chamber experiment. In addition to the direct emission of these contaminants, the surface reaction of NO2 and H2O to HONO is examined. In some cases this reaction may have as great an effect on a smog chamber experiment as the emission of trace contaminants. Overall chamber perturbations to gas phase chemistry have been estimated for several experiments and were found to be less than 20 percent in the majority of cases, although higher perturbations were found in experiments involving compounds of low reactivity such as butane.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 199
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 613-631 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The decomposition kinetics of disilane with added butadiene, trisilane both neat and with added butadiene, trimethylsilane or H2, and normal and iso-tetrasilane both neat and in the presence of added butadiene are reported. Arrhenius parameters of the primary dissociation reactions are determined: A-factors suggest that polysilane decompositions (1) have similar intrinsic activation entropies (ΔS
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 200
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 673-681 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The molecular modulation spectroscopic technique was employed to study the kinetics of NO3 radicals produced in the 253.7 nm photolysis of flowing gas mixtures of HNO3/CH4/O2 at room temperature. By computer fitting of the NO3 temporal behavior, a rate coefficient of (2.3 ± 0.7) × 10-12 cm3 molecule-1 s-1 was obtained for the reaction between NO3 and CH3O2 at 298 K.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...