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  • 1985-1989  (6,619)
  • Organic Chemistry  (3,492)
  • Engineering  (2,531)
  • Life Sciences  (596)
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  • 101
    Electronic Resource
    Electronic Resource
    The discrete time domain Green's function or Johns matrix  -  A new powerful concept in transmission line modelling (TLM)Invited Paper. (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 2 (1989), S. 215-225 
    Details
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: A new TLM-based concept analogous to the Green's function approach in classical electromagnetic theory is presented. It employs the procedure known as time domain diakoptics. The response of a TLM mesh to a unit impulse excitation at selected input points is interpreted as a discrete Green's function in the time domain, and the term ‘Johns matrix’ is proposed for this characteristic response. As in classical theory, the response of the mesh to an arbitrary excitation is found by convolving the excitation with its Johns matrix. This concept extends the generalized scattering parameter concept into the time dimension, opens unprecedented possibilities for partioning time domain problems at the field level, and permits large-scale preprocessing of substructures for computer-aided design. It also represents and elegant way of modelling broadband absorbing boundary conditions, imperfectly conducting walls and general frequency dispersive boundaries in the time domain.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jnm.1660020405
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  • 102
    Electronic Resource
    Electronic Resource
    Hydrogen-bonding. Part 4. An analysis of solute hydrogen-bond basicity, in terms of complexation constants (log K), using F1 and F2 factors, the principal components of different kinds of basicityPart 3. M. H. Abraham, P. P. Duce, D. V. Prior, R. A. Schulz, J. J. Morris and P. J. Taylor, J. Chem. Soc. Faraday Trans. 1, 84, 865 (1988). (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 243-254 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The principal components factors F1 and F2 in the equation \documentclass{article}\pagestyle{empty}\begin{document}$$ \log K = {\rm BDP}_0 + S_1 F_1 + S_2 F_2 $$\end{document} have been used to obtain S1 and S2 values for sets of hydrogen-bond bases against 32 reference acid/solvent systems. The constants S1 and S2 define an angle θ = tan-1 S2/S1 that is a measure of the electrostatic:covalent bonding ratio in the hydrogen-bond complex. It is shown that θ can vary from 53 (4-fluorophenol in CH2Cl2)to 86 degrees (Ph2NH in CCl4) depending on the reference acid and solvent. This variation in θ can lead to family dependent behaviour in plots of log K for bases against a given reference acid system vs log K for bases against another reference acid system, and precludes the construction of any general scale of hydrogen-bond basicity using log K values. Amongst a quite wide range of reference acid/solvent systems θ varies only from 64 to 73 degrees, and for bases against these reference systems a ‘reasonably general’ scale could be set up. Such a scale could be extended to bases against reference acid/solvent systems outside the 64-73 degree range provided that certain classes of base (e.g. pyridines, alkylamines) were excluded from the additional reference acid/solvent systems.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020307
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  • 103
    Electronic Resource
    Electronic Resource
    Application of Marcus theory to photochemical proton transfer reactions. II. Modifications based on intersecting state models (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 300-322 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Various modifications of the Marcus equation have been applied to the problem of photochemical proton transfer, using available data on general acid-catalyzed photohydration reactions. These include incorporation of asymmetry and tightness parameters, as well as distance variation as a function of exoor endothermicity. The intersecting state model of Formosinho has also been successfully applied to these reactions. The overall conclusion from all of these approaches is that the reactions are characterized by somewhat asymmetric and ‘loose’ transition states, with a small but significant degree of charge development on the in-flight proton at the transition state. Estimates of the intrinsic barriers and work terms place these in the 5-7 kcal and 2-3 kcal ranges respectively. A simple valence bond configuration mixing model leads to similar qualitative conclusions about the nature of the transition states in these reactions.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020403
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  • 104
    Electronic Resource
    Electronic Resource
    A theoretical and experimental investigation of acid catalyzed rearrangements of small [n]cyclophanes (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 331-348 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The difference in reactivity of small [n]cyclophanes towards CF3CO2H is discussed in terms of charge densities, strain energies and proton affinities. These data are calculated with MNDO and MINDO/3 for para-, meta- and ortho-cyclophanes and for their ipso-protonation products; an attempt is made to transform gas phase ΔHf0 values into liquid phase ΔH0f values. Experimental evidence is presented that the acid catalyzed rearrangement of [5]paracyclophane to its ortho-isomer proceeds via two consecutive 1,2-carbon shifts without deprotonation; intermediate adducts were identified by NMR-spectroscopy. Thus, a gradual shift in reaction pattern in the series [4]-, [5]- and [6]paracyclophane is observed experimentally, in line with the calculational results.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020405
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  • 105
    Electronic Resource
    Electronic Resource
    Masthead (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989) 
    Details
    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
    URL: http://dx.doi.org/10.1002/poc.610020501
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  • 106
    Electronic Resource
    Electronic Resource
    Free-radical reactions of cyclic ethers and sulfides with bromotrichloromethane (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 367-376 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The relative rates of hydrogen atom abstraction from a series of twelve saturated cyclic ethers and sulfides were determined at 70°C. The abstracting radical could be generated from bromotrichloromethane both photolytically or by the thermal decomposition of AIBN. The reaction rates did not show a dependence upon method of radical generation. Reaction occurred only at the position adjacent to the heteroatom. The reactivity of the cyclic ethers was in the order C4H8O 〉 C6H12O 〉 C3H6O 〉 C5H10O. This trend would indicate appreciable influence by ring strain, however, the slightly greater reactivity of tetrahydrofuran relative to oxepane suggests a contribution by stereoelectronic factors as well. The reactivity of the cyclic sulfides, which reacted faster than the corresponding ethers, was in the order C4H8S 〉 C5H10S 〉 C6H12S. This would imply little influence of ring strain. The major structural effect would be that of variable electron donating ability of the sulfur atom. The rate of reaction of thietane was also determined. It was found to preferentially undergo SH2 attack at the sulfur atom followed by ring opening rather than hydrogen abstraction. The reactivities of both series of compounds were decreased by the inductive effect of a second heteroatom beta to the reaciton site.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020502
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  • 107
    Electronic Resource
    Electronic Resource
    Group transfers 4. Arylselenide aniondiaryl diselenide exchange (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 410-416 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Barriers for group transfers between nucleophiles have been postulated to be lowered when the transferring group can carry a considerable negative charge. Furthermore, anions readily subject to one electron oxidation appear to lead to lower barriers than do those of high oxidation potential. These suggestions are pursued here on the identity reaction ArSe- + ArSeSeAr → ArSeSeAr + ArSe-. Indeed the reaction is very fast, as shown by the appearance of only a single peak in the 77Se-NMR in an acetonitrile solution containing both ArSeNa and ArSeSeAr. The rate constant can be only very roughly estimated at low temperatures and dilute solutions, and is likely diffusion controlled for Ar = phenyl and p-methoxyphenyl. A stable intermediate (ArSe)3-, analogous to Br3-, is indicated, but quantitative stability could not be determined, from either the NMR or the UV spectra. Some properties of 77Se-NMR are discussed.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020506
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  • 108
    Electronic Resource
    Electronic Resource
    Lack of protonation of benzene and toluene by trifluoromethanesulfonic acid and its significance for evaluating superacid strengths (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 425-427 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Distribution between pentane and trifluoromethanesulfonic acid (TFMSA) and carbon-13 NMR measurements showed that benzene and toluene are not protonated to any significant extent in TFMSA. This finding contradicts previous reports, and validates the ranking of superacids based on the extent of benzene protonation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020508
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  • 109
    Electronic Resource
    Electronic Resource
    Bifunctionally catalyzed 1,3-proton transfer of a propene by a sec-amidine studied by deuterium isotope effects. A stepwise two-proton transfer mechanism (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 429-447 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A two-hydron transfer mechanism involving hydron transfers from carbon to nitrogen and from nitrogen to carbon was studied. The rearrangement of 1,3,3-triphenylpropene (1) into 1,1,3-triphenylpropene (2) catalyzed by 2,10-diazabicyclo[4.4.0]dec-1-ene (3) in benzene at 25·00°C was studied by 2H-labeling experiments and kinetic 2H-isotope effects. The synthesis and purification of [6,10-2H2]-2,10-diazabicyclo[4.4.0]dec-1-ene ([6,10-2H2]-3), [3-2H]-1,3,3-triphenylpropene ([3-2H]-1), [3-2H]-1,1,3-triphenylpropene ([3-2H]-2) and [3,3-2H2]-1,1,3-triphenylpropene ([3,3-2H2]-2) together with their precursors are reported. Partial reaction of [3-2H]-1 with [6,10-1H2]-3 gave 42% conversion into product 2, which was shown by 1H NMR to be composed of 88% [3-1H]-2 and 12% [3-2H]-2. Partial reaction of [3-1H]-1 with [6,10-2H2]-3 gave 43% of 2, composed of 73% [3-1H]-2 and 27% [3-2H]-2.These results clearly show that a substantial fraction of the reaction takes place in a bifunctional manner but isotope exchange and/or monofunctionally catalyzed reactions interfere. The following kinetic deuterium isotope effects on the rearrangement 1 → 2 were measured: kHH/kDH = 6·56; kHH/kHD = 1·19; kHH/kDD = 7·08; kHD/kDD = 5·94; and kDH/kDD = 1·08.On the basis of these results, a concerted two-hydron transfer mechanism is excluded. Instead, a stepwise mechanism is favored, in which at first the 3-hydron of 1 is abstracted by 3 yielding an ion pair(s), the carbanion of which in a separate step is then hydronated to yield the product 2.The abstraction of the 3-hydron from 1 might be hydrogen bond assisted. The two hydron transfer transition states are together rate limiting, although they limit the rate to different extents. A detailed mechanistic analysis is presented together with the results of an investigation of the nature of the catalyst. The dimerization constant for 3 was determined by 1H NMR to be 1·67 l mol-1 at 25·0°C. Isotopomer composition was measured by 1H NMR and GLC was used for the separation of the substrate and products. Computer-assisted capillary GLC was used for the kinetics.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020602
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  • 110
    Electronic Resource
    Electronic Resource
    Cross-interaction constants as a measure of the transition state structure (part V).For Part IV, see ref. 3. The transistion state structure for reactions of phenacyl benzenesulphonates with benzylamines in methanol (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 484-490 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The Kinetics of reactions of phenacyl benzenesulphonates with benzylamines were investigated in methanol at 45·0 °C and the cross-interaction constants λXY, λYZ and βXZ were determined in order to elucidate the transition-state structure. The unusually small magnitude of λXY can only be accounted for by the resonance ‘shunt’ effect of the α-CO group of the phenacyl system. Large |λYZ| values indicate a small degree of bond breaking whereas relatively large |βXZ| values compared with those for the dissociative SN2 reaction indicate a relatively tight transition state for the reactions. Further, the similar magnitudes of βXZ values compared with those of the corresponding aniline nucleophile series suggest a similar transition-state structure for the two armatic amine nucleophile series.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020607
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  • 111
    Electronic Resource
    Electronic Resource
    Amines as leaving groups in nucleophilic aromatic substitution reactions. II.For Part 1, see Reference 1. Hydrolysis of N-(2,4,6-trinitrophenyl)amines (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 507-518 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The hydrolysis reactions of N-(2,4,6-trinitrophenyl)piperidine (2) and N-(2,4,6-trinitrophenyl)-morpholine (3) were studied. Two kinetic processes well separated in time are observed in both reactions. The fastest process, which is reversible, leads to the formation of a species of λmax 260 and 410 nm and is attributed to the formation of a σ complex of stoichiometry 1 : 2 due to the addition of a second HO- to the σ complex of 1 : 1 stoichiometry. The slowest process leads quantitatively to picrate ion. The equilibrium constants for the formation of the σ complexes of 1:1 and 1:2 stoichiometries and the rate of formation and decomposition of the latter complex were determined. The kinetic data for the slow process lead to the conclusion that the picrate ion is formed from the attack of HO- on the two σ complexes, confirming previous findings. There are some differences in the calculated rates for 2 and 3 which may be an indication that the elimination of the amine is partially rate determining.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020703
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  • 112
    Electronic Resource
    Electronic Resource
    Decarboxylation of 6-nitrobenzisoxazole-3-carboxylate ion in cationic micelles: Effect of head group size (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 553-558 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The rate of decarboxylation of 6-nitrobenzisoxazole-3-carboxylate ion increases sharply with increasing head group size in a series of cetyltrialkylammonium bromides (C16H33NR3Br: R = Me, CTABr; R = Et, CTEABr; R = n - Pr, CTPABr; R = n - Bu, CTBABr) with rate enhancements of 102 (CTABr) and 2·8 × 103 (CTBABr). Micellized tetradecylquinuclidinium bromide and hexadecyl-N-methylmorpholinium bromide are slightly better catalysts than CTABr, as is 1,3-bis(N-cetyl-N,N-dimethylamino)propane dibromide, but p-octyloxybenzyltrialkylammonium bromides (alkyl = Me, n - Bu) are less effective than the corresponding CTA+ surfactants. These differences in catalytic efficiency depend on the head group structure and the extent to which the cationic head groups become less accessible to water rather than the overall micellar structure.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020707
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  • 113
    Electronic Resource
    Electronic Resource
    Thermodynamic and spectroscopic properties of 2-pyrrolidinones. 3.For Part 2, see P. Ruostesuo and P. Pirilä-Honkanen, submitted for publication, J. Sol. Chem. NMR spectroscopic studies on 2-pyrrolidinone in different solvents (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 565-572 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 1H, 13C, 15N and 17O NMR chemical shifts, 1JNH and 1JCH coupling constants and line widths (Δν1/2) of the 14N and 17O resonance lines were determined for 2-pyrrolidinone neat and for several 2-pyrrolidinone-solvent systems. The 17O NMR chemical shift of 2-pyrrolidinone was clearly most sensitive to the solvent effects, but changes with the solvent were also observable in the 13C (C=O) and 15N NMR chemical shifts, the 1JNH coupling constants and especially the line widths of the 14N and 17O resonance lines. In general, the results reflected a hydrogen bonding effect between the oxygen atom of 2-pyrrolidinone and the proton-donating solvents and a weak molecular interaction of the NH proton of 2-pyrrolidinone with the proton-accepting solvents. The results are compared with the NMR data for the corresponding binary mixtures of 1-ethyl-2-pyrrolidinone.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020709
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  • 114
    Electronic Resource
    Electronic Resource
    Anionic nucleophile-cation radical combination reactions. The super-electrophilic properties of cation radicals in solution (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 580-584 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Rate constants were determined for the combination reactions of a series of cation radicals derived from substituted anthracenes with acetate, p-nitrobenzoate, trifluoroacetate, nitrate and perchlorate ions. Rate constants, depending on the identities of the cation radicals and the nucleophiles, ranging from about 200 to 2 × 1010 1 mol-1 s-1 were observed in acetonitrile at 293 K. The key steps in the reaction are (1) reversible complex formation between the anion and the cation radical followed by (2) irreversible bond formation \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {\rm{Ar}^{ + \cdot } + \rm{X}^ - \rightleftharpoons {{\rm{Ar}^{ + \cdot } } \mathord{\left/ {\vphantom {{\rm{Ar}^{ + \cdot } } {\rm{X}^ - }}} \right. \kern-\nulldelimiterspace} {\rm{X}^ - }}} &&&&& {(1)} \\ {{{\rm{Ar}^{ + \cdot } } \mathord{\left/ {\vphantom {{\rm{Ar}^{ + \cdot } } {\rm{X}^ - }}} \right. \kern-\nulldelimiterspace} {\rm{X}^ - }} \to \rm{Ar}^ \cdot - \rm{X}} &&&&& {(2)} \\ \end{array} $$\end{document}.The preliminary results show that cation radical-anionic nucleophile reactions can be very facile. The cation radicals of 9-nitro- and 9-cyanoanthracene are particularly reactive, giving rise to rate constants close to the diffusion-controlled limit with all anionic nucleophile studied and even react moderately rapidly with perchlorate ion. The reaction with perchlorate ion can be compared to the behavior of stable carbenium ions that coexist with the anion in solution and in crystalline salts.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020711
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  • 115
    Electronic Resource
    Electronic Resource
    Analysis of solvent effect on SN2 reactions by different theoretical models (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 611-622 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The solvent effect on two SN2 reactions was evaluated by discrete, continuum and discrete-continuum models. The potential energy profiles were found to change dramatically on introduction of the solvent effect. The double-well shape which characterizes the F- + CH3F → FCH3 + F- reaction in the gas phase becomes unimodal when the solvent is introduced, in good agreement with experimental data. The solvation parameters are found to intervene in the reaction coordinate. Recent Monte Carlo and molecular dynamics calculations are discussed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020804
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  • 116
    Electronic Resource
    Electronic Resource
    Comparative kinetic study of solvent effects in the reactions of 1,2-dinitrobenzene with butylamine and piperidine (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 631-645 
    Details
    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 aromatic nucleophilic substitution (SNAr) reactions of 1,2-dinitrobenzene (1,2-DNB) with butylamine (BA) and piperidine (PIP) were investigated as a function of the amine concentration and temperature, in chloroform, ethyl acetate, tetrahydrofuran (THF), acetonitrile (ACN), dimethylformamide (DMF), dimethyl sulphoxide (DMSO). benzene, toluene, chlorobenzene and diisopropyl ether.In the set of solvents consisting of ethyl acetate, THF, ACN, DMF and DMSO, neither reaction is catalysed (kA = k1). The sequence and range of reactivity for BA and PIP are similar in these solvents. These results indicate that reactions in which nitro in the leaving group behave differently from SNAr reactions with other leaving groups, such as halogens or alkoxy groups, since an intramolecular hydrogen bond may be expected between the leaving nitro group and the ammonium H of the nucleophiles. The correlations of the rate coefficients obtained with Taft and Kamlet's solvatochromic method support these conclusions.On the other hand, these reactions show mild acceleration with relatively non-polar solvents such as the aromatics and diisopropyl ether. The donor properties of these solvents and experiments with solvent mixtures suggest the formation of electron donor-acceptor complexes between them and 1,2-DNB. Hence the preferential solvation of 1,2-DNB by the donor solvent accounts for the mechanism observed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020806
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  • 117
    Electronic Resource
    Electronic Resource
    Selective 1,2-addition of organocerium(III) reagents to α,β-unsaturated carbonyl compounds (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 93-102 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Organocerium(III) reagents reacted with α,β-unsaturated carbonyl compounds to give 1, 2-addition products (allylic alcohols) in good to high yields. The reaction was studied from a mechanistic point of view by the use of (E)- and (Z)-1-(4′-methoxyphenyl)-3-phenyl-2-propen-1-ones and 4,4-ethylenedioxy-2,6-dimethyl-2,5-cyclohexadienone as the probe compounds. A polar pathway was suggested for the reaction with the former enones. On the other hand, the operability of single electron transfer processes was demonstrated in the reaction with the latter probe compound.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020202
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  • 118
    Electronic Resource
    Electronic Resource
    Formation of 1:1 adducts between bis(1,2-diaryl-1,2-ethylenedithiolato)metal(0) (metal = NI, PD, and PT) and quadricyclane and their photodissociation (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 131-145 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Bis(1,2-diaryl-1,2-ethylenedithiolato)metal(0) complexes (1; metal = Ni, Pd, and Pt) react with quadricyclane (Q) to give selectively 1:1 adducts which are identical with the adducts between 1 and norbornadiene (NBD). In the adducts, two sulfur atoms of the different dithiolato ligands are added to one of the double bonds of NBD. The reactions of 1 with Q are 103-104 times faster than those with NBD. The more electropositive dithiolatometal complexes react faster with Q and NBD. The adducts are dissociated to the free dithiolatometal complexes and NBD by UV-irradiation (254-436 nm). Upon irradiation with 254 nm light, the photodissociation occurs before the decomposition of the dithiolatometal complexes.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020206
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    Gas phase reactivities of isomeric ions: Methylenediphenylcyclopropane and diphenylmethylenecyclopropane (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 117-130 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Gas phase ion/molecule reactions have been used to probe the structure of ions obtained by electron impact upon 1-(diphenylmethylene)cyclopropane and 2,2-diphenyl-1-methylenecyclopropane. The resulting ions of molecular composition C16H14 (m/z 206+) were reacted with charge transfer reagents (6·9 〈 IP 〈 8·8eV), giving evidence for the presence of isomeric ions with different reactivities. The less reactive ion is identified as a trimethylenemethane species (TMM+) in which one cyclopropane bond is broken; the more reactive ions are assigned as vertical ions in which the cyclopropane ring is unaffected. The vertical ions have recombination energies of 8·44 ± 0·05eV, whereas TMM+ has one of 7·41±0·05eV. The TMM+ fraction is not constant; it increases with increasing IP of the reagent. This is attributed to a reagent-catalyzed isomerization of the vertical ion to TMM+. In addition, the reagent ions are observed to undergo a unique reaction with the neutral methylenecyclopropane derivatives: electron transfer and ring opening to yield TMM+. These findings limit the application of the customary equilibrium measurements as a method to determine the substrate IP.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020205
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  • 120
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    General base catalysis of photo-smiles rearrangement of 1-(4-nitrophenoxy)-2-anilinoethane in aqueous solution. Identity of the proton-donating intermediate (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 177-182 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 4-O2NC6H4OCH2CH2NHPh undergoes clean base-catalyzed Smiles photorearrangement to 4-O2NC6H4N(Ph)CH2CH2OH in dimethyl sulfoxide-water (25:75). A linear plot of φ-1 vs [OH-]-1 indicated that the limiting quantum yield at high [OH-] is 0·12 and that uncatalyzed photorearrangement does not occur. Rate constants for the deprotonation step were determined for a variety of bases having conjugate acid pKa values in the range 5-10. When plotted according to the Brønsted Catalysis Law, these data gave a non-linear plot approaching slopes of zero and unity above and below a pKa of 6-7. This indicates that the proton-donating intermediate in this photo-Smiles rearrangement is the zwitterion diradical (pKa ≈ 7) rather than the Meisenheimer complex (pKa ≈ 2).
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020209
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  • 121
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    Theoretical study of pyrazole elimination of N-alkyl pyrazoles (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 225-231 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The gas-phase pyrazole elimination of N-alkyl pyrazoles has been studied using MNDO semi-empirical molecular orbital (MO) theory with complete geometry optimization of all stationary points. We found that the activation energies (Ea) of the concerted processes are around 80 kcal/mol, 25 Kcal/mol higher than experimental values. But the differences in Ea between compounds with different substituents are in good agreement with the experimental ones.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020305
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  • 122
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    Photostimulated reactions of neopentyl halides with nucleophiles by the SRN1 mechanism (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 255-262 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The photostimulated reaction of neopentyl halides with different nucleophiles by the SRN1 mechanism of nucleophilic substitution has been studied. Neopentyl halides do not react with carbon nucleophiles, diethylphosphite, diphenylphosphonite and azide ions, but they react with arsenide and selenide ions. The photostimulated reaction of neopentyl bromide with diphenylarsenide ions gave only the straightforward substitution product neopentyldiphenylarsine. On the other hand, the photostimulated reaction of bromobenzene with dineopentyl arsenide ions gave three arsines: dineopentylphenylarsine, neopentyldiphenylarsine and triphenylarsine. Neopentyl chloride reacts under irradiation with diphenylphosphide ions giving good yields of the substitution product.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/poc.610020308
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    Masthead (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989) 
    Details
    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
    URL: http://dx.doi.org/10.1002/poc.610020401
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  • 124
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    Theoretical studies on the hydrolysis of urea in acid solution (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 281-299 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Mechanisms of the hydrolysis of urea have been investigated using the MNDO and AMI methods. All geometries were fully optimized and the transition states were characterized by calculating force constants. The results showed that: (i) The unimolecular decomposition process via the direct intramolecular proton transfer is preferred to both the A1 and the bimolecular nucleophilic attack by water, in agreement with the experimental results of Shaw et al. in the low acidity medium. (ii) The diprotonated form of urea exists as an equilibrium species, which undergoes the A2 type hydrolysis more favorably than the monoprotonated form, as Moodie et al. found in the intermediate acidity medium. (iii) The A2 hydrolysis of the monoprotonated form is very similar to those of acetamide and methyl carbamate. (iv) As the number of the solvate water molecules increases, the activation barrier for the A2 process of the monoprotonated form increases while that for the unimolecular decomposition of the free base form decreases, indicating a possibility of the barrier height reversal in the bulk solvent in favor of the latter process, thus accommodating all the experimentally found trends in the urea hydrolysis. The A1 mechanisms involving six-membered ring type intermediates can be ruled out as untenable since no such equilibrium species was obtained by both the MNDO and AM1 calculations.
    Additional Material: 17 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020402
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  • 125
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    Lack of manifestation of an anomeric effect in 2-diphenylphosphinoyl-1, 3-dioxane and 2-diphenylphosphinoyl-1, 3-oxathiane1Dedicated to Prof. Xorge A. Domínguez, Tecnológico de Monterrey, on the occasion of his 60th birthday. (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 349-358 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The spectroscopic evidence for the predominance of the equatorial conformers in the title compounds was confirmed by the study of derivatives containing counterpoise substituents, and by chemical equilibration of anancomeric models. ΔG27o°C [P(O)Ph2] ≳ 3·2 kcal/mol was determined in the dioxane, and ΔG55o°C [P(O)Ph2] = 1·42 ± 0·12 kcal/mol in the oxathiane. It follows then that the strong anomeric interaction observed previously in S—C—P segments does not show up in the six-membered heterocycles 2 and 7, which contain O—C—P moieties. This may be due to an inherent inability of oxygen to act as an electron donor to the axial P(O)Ph2 substituent, or to a dominant repulsive steric interaction in the axial conformers.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/poc.610020406
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  • 126
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    Oxygen-17 NMR study on substituted α, α, α-trifluoroacetophenonesPart VI of Nuclear Magnetic Resonance Studies. For Part V, see. K.-T. Liu, Tetrahedron Lett. 1207-1208 (1977). (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 363-366 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An excellent linear correlation of oxygen-17 substituent chemical shifts (SCS) for twelve α, α, α-trifluoroacetophenones with single σ+ constants, δ = 24·6σ+ + 556·3 (correlation coefficient 0·998) has been observed. However, from this plot, an SCS of 34·3 ppm for 1,1,1-trifluoroacetone will give a corresponding σ+ (γ+) value of 1·44 for a methyl group, which is not in agreement with 0·63-0·79 obtained from solvolytic rate data.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020408
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  • 127
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    Photochemistry of matrix-isolated norbornadiene (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 383-388 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Norbornadiene, isolated in argon, xenon and nitrogen matrices at 20 K, was irradiated with UV light. Characterized by UV-VIS-IR absorption spectroscopy the photoproduct, representing a single species, was assigned to quadricyclane. This result is compared with the literature data on photochemistry of norbornadiene in the gas and liquid phase. The role of the rigid matrix environment on selectivity of the photochemical reaction is discussed.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020504
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    Masthead (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989) 
    Details
    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
    URL: http://dx.doi.org/10.1002/poc.610020601
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    Binding of pyridoxal-5′-phosphate and pyridoxamine-5′-phosphate: Electrochemical characterization (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 448-454 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The interaction between pyridoxal-5′-phosphate (PLP) and pyridoxamine-5′-phosphate (PMP) was studied by d.c. and differential pulse polarography. Two reduction waves (or two peaks) were observed. The first wave corresponds to the reduction of the adduct and the second to the reduction of free PLP. The behaviour was similar in analogous Schiff bases. The effects of pH, PMP concentration and the capillary characteristics were studied. The apparent formation constant as a function of the pH was calculated. Thermodynamic parameters were estimated at pH 7 and 0 · 1 M ionic strength. The polarographic and kinetic results show that the overall electrode process appears to be irreversible in a basic medium.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020603
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  • 130
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    Dipole moments and electron distribution of acyl chlorides and acyl bromides (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 476-483 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Dipole moments of para-substituted benzoyl chlorides and bromides, partly measured in benzene and partly recalculated from elderly literature, were analysed in terms of bond moments and additional contributions expressing the conjugation. Although the gross moments are similar, their decomposition yields different pictures for acyl chlorides and bromides. Only in the latter can significant electron transfer from the halogen be observed. On the other hand, conjugation with the benzene nucleus is strong in both aromatic acyl chlorides and bromides, but stronger in chlorides. There is agreement with the evidence from some other physical quantities but not from all.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020606
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  • 131
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    Aromatic substitution by free benzyl cations from the nuclear decay of multi-tritiated toluene. Competitive benzylation of benzene and toluene in the gas phase and in solution (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 467-475 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Benzyl cations, free of counter ions, have been generated from the nuclear decay of tritium atoms contained exclusively in the side-chain of multi-labelled toluene and allowed to react in competition experiments with benzene and toluene. The aromatic substitution was studied in both the gaseous and liquid phase, employing pure aromatics or aromatics dissolved in n-hexane, carbon tetrachloride and nitromethane as the reaction medium. In the gaseous systems, at 20 Torr total pressure, High meta substitution of toluene indicates extensive isomerization of the excited intermediates, while the increase of the kT/kB value in the Presence of NH3 suggests that selective transalkylation competes with proton transfer to ammonia from the benzyl cation adducts with benzene, but not with toluene. High positional and low substrate selectivities were measured in solution, the decrease in kT/kB (from 2·8 to 1·7) in the different solvents being accompanied by an increase in the o/2p ratio. Competition experiments between benzene and methanol indicate that the reaction is not diffusion controlled. The influence of the reaction medium on the substrate selectivity is explained by postulating the formation of a cation-solvent adduct, where the solvent molecule undergoes displacement by the substrate. Positional selectivity would be controlled in a subsequent step.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/poc.610020605
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  • 132
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    Micellar catalysis of organic reactions. 24.For Part 23, see T. J. Broxton, J. R. Christie and R. P.-T. Chung, J. Org. Chem. 53, 3081 (1988). Comparison of SNAr reactions in hydroxy-functionalized micelles and in the presence of cyclodextrins (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 519-530 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The basic hydrolysis of 2,4-dinitrochlorobenzene (DNCB) and 2,4-dinitrofluorobenzene (DNFB) was studied in the presence of β-cyclodextrin (CDOH) and in the presence of hydroxy-functionalized micelles containing either a primary hydroxy group [hexadecyl-2-hydroxyethyldimethylammonium bromide (CHEDAB)] or a secondary hydroxy group [headecyl-2-hydroxypropyldimethylammonium bromide (CHPDAB) and 2-hydroxyhexadecyltrimethylammonium bromide (2-OHCTAB)].In all systems a biphasic reaction was observed. The first phase consisted of a competition between the additive (either micelle or cyclodextrin) and hydroxide ion for the aromatic substrate, and the second phase consisted of the hydrolysis of the trapped aryl micellar or cyclodextryl ether.The percentage of trapping of the aromatic substrate by the cyclodextrin was similar to that found for reactions in the hydroxy-functionalized micelles (CHPDAB and 2-OHCTAB) which contained secondary hydroxy groups. The relative rates of reaction for DNFB and for DNCB, i.e. F/Cl rate ratios, in the presence of CDOH were similar to those obtained in the presence of 2-OHCTAB but less than that obtained in the presence of CHEDAB. These results support the assumption that in CDOH the secondary hydroxy groups of C-2 or C-3 are involved in covalent bond formation with the aromatic substrate rather than the primary hydroxy group of C-6. All the reactions studied proceed much more slowly in the presence of CDOH than in the presence of the hydroxy-functionalized micelles. This may reflect a catalytic effect of the positively charged surface present in the micelles but not in the cyclodextrin.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020704
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    Hydrogen-bonding 8.Part 7; M. H. Abraham, P. L. Grellier, D. V. Prior, P. P. Duce, J. J. Morris and P. J. Taylor. J. Chem Soc., Perkin Trans. 2, (in press). Possible equivalence of solute and solvent scales of hydrogen-bond basicity of non-associated compounds (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 540-552 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Using the solvatochromic indicator method, a scale of solvent hydrogen-bond basicity, β1 (General), has been set up using a series of double regression equations, \documentclass{article}\pagestyle{empty}\begin{document}$$ \nu = \nu _0 + s\pi _1^* + b\beta _1 $$\end{document} for 11 aniline-type indicators. A similar solvent scale, β1 (Special), has been constructed by the homomorphic comparison method using only results by Laurence et al. on the indicators 4-nitroaniline and 4-nitro-N,N-dimethylaniline. Results are available from our previous work on a general solute scale, β2H, and we have also obtained a special solute scale, β2 (pKHB) from available log K values for hydrogen-bond complexation of bases with 4-fluorophenol in CCl4. However, the two solute β2 scales are virtually identical.It is shown that there is a general connection between β1(General) and β2H, with r = 0·9775 and s.d. = 0·05 for 32 compounds, and between β1(Special) and β2H, with r = 0·9776 and s.d. = 0·06 for the same 32 compounds. The latter correlation over 60 compounds yields r = 0·9684 and s.d. = 0·07. However, there are so many compounds in these regressions for which the differences in the solvent and solute β values are larger than the total expected error of 0·07 units that the use of β1 to predict β2 or vice versa is a very hazardous procedure. About 70 new β1 values obtained by the double regression method are also reported.
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    URL: http://dx.doi.org/10.1002/poc.610020706
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    Molecular mechanics (MM2) calculations on siloxanesThis paper is taken from Ref. 1. (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 573-579 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The MM2 force field has been extended so that calculations may be carried out on siloxanes. The parameters chosen give a good fit to available experimental data.
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    URL: http://dx.doi.org/10.1002/poc.610020710
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    Energy-minimum structure of the hydrocarbon portion of [45] (1,2,3,4,5)ferrocenophane (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 602-610 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In order to assist in the interpretation of the D5h molecular structure of [45] (1,2,3,4,5)ferrocenophane (1) obtained from x-ray crystallographic analysis, a hypothetical hydrocarbon C30H40 (2) was derived from 1 by removing the iron atom and subjected to geometry optimization by molecular mechanics. A stable D5 conformer was found for 2, which has a g+ g- g+ helical bridge conformation and a ring-ring distance almost identical with that in 1 and ferrocene itself. Optimization of a perhydrogenated hydrocarbon model gave a highly strained C1 structure.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020803
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    The double photodissociation of a geminal dichloride: Evidence for the stepwise formation of a diaryl carbene (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 623-630 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Photolysis of dichlorodiphenylmethane in glassy 2-methyltetrahydrofuran at 77 K results in the formation of diphenylcarbene and the diphenylchloromethyl radical, which were detected by their fluorescence emission and excitation spectra. The relative yields of the carbene and biradical are shown to vary dramatically as a function of photolysis time. The photolability of the diphenylchloromethyl radical is also demonstrated. These results were interpreted in terms of a two-step mechanism, in which the diphenylchloromethyl radical is an intermediate in the formation of diphenylcarbene.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020805
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    Self-catalysis and molecular complexes in aromatic nucleophilic substitution reactions: Reaction between 1,3,5-trinitrobenzene and 1,8-diazabicyclo [5.4.0] undec-7-ene in toluene (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 653-659 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The formation of a σ-like complex by reaction between 1,3,5-trinitrobenzene and 1,8-diazabicyclo [5.4.0]-undec-7-ene was investigated in toluene at various temperatures. The kinetic data showed autocatalytic behaviour. Inspection of the reaction mixtures at zero reaction time indicated the presence of an equilibrium preceding the attack of the nucleophile, affording a molecular complex (substrate-nucleophile) which is responsible for the observed kinetic features. The present and the previous data led to the conclusion that the catalytic behaviours usually observed in SNAr reactions (in apolar solvents with amines as nucleophiles) are better explained by the presence of substrate-catalyst interactions than by catalysis on departure of the proton and leaving group from the zwitterionic intermediate.
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    URL: http://dx.doi.org/10.1002/poc.610020808
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    Masthead (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989) 
    Details
    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
    URL: http://dx.doi.org/10.1002/poc.610020701
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    Reflections on the π-complex theory of benzidine rearrangementsDedicated, with respect, for the 70th birthday of Professor Michael Dewar, who, on scribbled, lunch-time table napkins at the 1961 American Chemical Society meeting in Chicago tried but (fortunately) failed to convince me of the validity of his π-complex theory. I wish I had kept the napkins. (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 491-506 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The ups and downs, and reasons therein, of the π-complex theory of the mechanism of the benzidine rearrangements, and the possible role of π-complexes in a newer understanding of the rearrangements, are described.
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    URL: http://dx.doi.org/10.1002/poc.610020702
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    Influence of aromatic substituents on the configuration and conformation of calix[4]areneoctols (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 531-539 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Acid-catalysed condensation of resorcinol with aromatic aldehydes results in 2,8,14,20-tetrasubstitued calix[4] areneoctols. Sixteen compounds of this type containing different aromatic substituents were synthesized. The ring closure step, under the conditions of the reaction, is a reversible process. Four configurations are possible for every constitution, viz. cccc, cctt, ccct and ctct, but only cccc and cctt were formed in detectable amounts. In seven cases the thermodynamically more stable cccc isomers (1a-5a, 7a, 8a) and also the kinetically controlled cctt isomers (1b-5b, 7b, 8b) could be isolated. The configurations of the compounds were assigned by temperature-dependent 1H NMR analysis. The conformational motions of the macrocyclic ring permit only the cccc isomers to show coalescence for the signals of the aromatic Hb protons. The coalescence temperature was determined for isomers 1a (ΔG384≠ = 83·5 kJmol-1) and 3a (ΔG369≠ = 83·7 kJ mol-1). For steric reasons the ‘chair-chair’ conformers B and the ‘quasi-boat-chair’ conformers F are favoured. 1H and 13C NMR shifts show that compounds 1a-5a and 1b-5b have a quasi-axial arrangement of the aromatic substituents, whereas 6-9 have a quasi-equatorial arrangement of the substituents.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020705
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  • 141
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    The use of IR spectroscopy to monitor the conversion of matrix isolated phenylacetyl chloride to phenylacetyl cation, without decarbonylation to benzyl cation (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 51-56 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: IR spectroscopy is presented as a convenient means to monitor the formation of acyl (and alkyl) cations from corresponding acid chlorides, with Lewis acids at low temperature in the solid state. Phenylacetyl chloride is co-deposited (under vacuum at -173°C with antimony pentafluoride on a KBr window), as in the ‘molecular beam’ method of cation generation. The initial IR spectrum of the deposition shows (in addition to starting materials) that a small amount of phenylacetyl cation (2274 cm-1) has been formed. Warming the solid matrix to -123°C Promotes the smooth conversion of acid chloride to acyl cation. Ultraviolet irradiation (through quartz windows) at -123°C to -73°C facilitates this conversion but does not result in the loss of carbon monoxide from the acyl cation to form benzyl cation. When benzyl chloride is used in place of phenylacetyl chloride, there is no noticeable difference between IR spectra taken before and after warming and/or photolysis of the solid deposition.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020107
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  • 142
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    Long range electrical field effects in solvolysis and 13C-NMR shielding of androstanes with halogen, hydroxy and oxo substituents (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 214-224 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The solvolysis of 21 different 3- or 17-androstanyl tosylates or chlorides with halogen, hydroxy or oxo substituents in 17- or 3-position shows rate constant variations in hexafluoro isopropanol of up to 6·3 with regular differences for epimeric substituents. Similar variations ae seen over a distance of ∼10 Å in 13C-NMR shifts at C-17-ones of androstan-17-ones with varied halogen substituents in C-3, whereas the shielding observed at other distant carbon atoms excludes significant through bond effects. It is shown how, on the basis of suitable Coulomb-type equations and of force field minimized geometries, both the stability variation of carbocationic transition states and the carbonyl group polarization are predictable by linear electric field effects, using the same parametrization.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020304
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  • 143
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    Alkylating properties of phosphate esters. 3. Reactivity of dialkyl 2-(dimethylamino) ethyl phosphates (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 263-270 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Reactivity of dialkyl 2-(dimethylamino)ethyl phosphates, (RO)2P(O)OCH2CH2NMe2 (R = Me, PhCH2) was studied in aqueous solutions. Depending on the initial substrate's concentration, reaction can involve the unimolecular fragmentation to N,N-dimethylaziridinium dialkylphosphate, or the bimolecular isomerization to the zwitterionic derivative. The latter reaction proceeds via two consecutive SN2 steps and involves the formation of two ionic intermediates which were synthesized independently and allowed to react to give the zwitterionic product. Rate constants for the isomerization of the dimethyl ester (R = Me), as well as rate constant for the reaction between the corresponding intermediates have been determined, and the reactivity of the dimethyl ester has been compared with that of the dibenzyl derivative.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020309
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  • 144
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    Crystal and molecular structures of dimesitylketene and bis(3,5-dibromo-2,4,6-trimethylphenyl)ketene. Intrinsic torsional angles and buttressing effects in 1,1-dimesitylvinyl propellers (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 271-280 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The crystal and molecular structures of dimesitylketene (1) and bis(3,5-dibromo-2,4,6-trimethylphenyl)ketene (2), the first free ketenes to be studied by X-ray diffraction, have been determined. The molecules of 1 and 2 have crystallographic C1 and C2 symmetry, respectively, and exist in a propeller conformation. Molecular mechanics calculations of 1 and 2 using a modification of Allinger's new allene parameters reproduce satisfactorily the structural parameters of the ketenes. The torsional angles of the aryl rings in 1 and 2 are similar (ca. 50°) and are regarded as ‘intrinsic’ values for a 1,1-dimesitylvinyl propeller. From the similarity in aryl torsional angles in 1 and 2 it is concluded that the buttressing effects in 2 (if any) are not markedly manifested in the structural parameters of 2.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020310
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  • 145
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    Laser flash photolysis of a chromium carbene complex: Pentacarbonyl(1,3-dimethyl-4-imidazolin-2-ylidene)chromium(0) (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 323-330 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Photoreactions of Cr(CO)5(Im) (Im = 1,3-dimethyl-4-imidazolin-2-ylidene) have been investigated by laser flash and continuous photolysis. Quantum yields for the disappearance of Cr(CO)5(Im) in benzene under Ar or CO were very low, although transients observed by laser flash photolysis reacted rapidly with CO. This suggests that photodissociation of the carbene ligand is very minor. The laser flash photolysis at 337 nm in benzene (B) gave a transient (λmax = 630 nm), which converted to the second transient (λmax = 455 nm) within ∼100 ns. The kinetic studies of these transients revealed that the first one is a ‘free’ coordinatively unsaturated species (Cr(CO)4(Im)) and the second one carries a solvent molecule as a ligand (Cr(CO)4(Im)(B)). From the comparison of Cr(CO)4(Im) and Cr(CO)5, apparently lower reactivity of Cr(CO)5 was found to be due to the strong coordination of a solvent molecule. The Im ligand neutralizes the deficit of electron density on Cr. A simple synthesis of Cr(CO)5(Im) was also described.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020404
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  • 146
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    A mechanistic study of the selenium-catalysed carbonylation of secondary amines with carbon monoxide (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 359-362 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The reaction pathway of urea formation by selenium-catalysed carbonylation of secondary amines with carbon monoxide in the presence of oxygen was studied using piperidine as a secondary amine. It was established that selenium reacts with carbon monoxide and piperidine to give carbamoselenoate as an intermediate, which affords biscarbamoyl diselenide by the oxidation with molecular oxygen. Aminolysis of biscarbamoyl diselenide gives the urea derivative, accompanying the regeneration of selenium catalyst.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020407
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  • 147
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    Alkylating properties of phosphate esters. 4. Medium effects on methylation of pyridines by trimethyl phosphate (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 377-382 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The rates of N-methylation of pyridine and its ring-substituted derivatives by trimethyl phosphate were measured in D2O and in CDCl3. Relative rates, together with the solvent activity coefficients of substrates for the transfer form chloroform to water, were used for determining the solvent activity coefficients of the activated complexes for this SN2 reaction. The results indicate early activated complexes for all pyridines, with the most nucleophilic substrate showing the most reactant-like activated complex.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/poc.610020503
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  • 148
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    Experimental determination of carbon vs. oxygen regioselectivity in reactions of gas-phase enolate ions (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 389-409 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A gas-phase experimental investigation of the competition between carbon and oxygen alkylation of a series of cyclic and acyclic enolate ions is described. Perfluoropropylene is shown to react in a characteristic way with oxyanions and carbanions to produce distinctive ionic products. The relative yields of these products formed in reactions with ambident enolate ions provides a measure of their intrinsic carbon vs. oxygen regioselectivity. The results for a series of enolates derived from aldehydes, ketones, esters, amides and related compounds show a wide range of reactivity which is a function of the nature of the central substituent. Most aldehyde and ketone enolates react mainly through oxygen, while enolates with σ-acceptor of π-donor type central substituents react mainly thorugh carbon. Ring-size in cyclic ketone enolates also influences C vs. O regioselectivity, i.e. small-ring enolates react mainly through carbon, while larger ring enolates (C7-C9) react preferentially through oxygen. The enolate reactivity patterns can be generally accounted for by the keto-enol energy differences for the parent carbonyl compounds, although some exceptions are evident. The origins of the highly variable, kinetically determined regioselectivities are discussed.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020505
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  • 149
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    ESCA studies of carbanionic compounds: Butyllithium in heptane solution and dibutylmercury in the gas phase (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 417-424 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Two organometallic reagents, butyllithium in heptane solution and dibutylmercury in the gas phase, have been studied by means of core electron spectroscopy. The property of particular interest was the charge polarization as reflected by the ESCA shifts. In the butyllithium compound the C1s binding energy is shifted to a lower value by 1·8 eV for C-1 (situated closest to the Li+ ion) relative to the heptane solvent carbon. This is due to the anionic character of the C-1. The interpretation of the experiments was supported by comparing the results with ab initio calculations made on geometry-optimized butyllithium, butyl anion and butane.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020507
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  • 150
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    Dynamic isotope dilution kinetic study of the thermal conversions of bicyclo[3.2.0]hept-2-ene to bicyclo[2.2.1]hept-2-ene and to cyclopentadiene and ethene (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 455-466 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Mixtures of bicyclo[3.2.0]hept-2-ene and bicyclo[2.2.1]hept-2-ene, with one isomer labeled with two deuterium atoms, were isomerized in the gas phase at 276 °C. By following the concentration ratios of d0 and d2 versions of bicyclo[2.2.1]hept-2-ene as functions of time one finds that the partitioning of bicyclo[3.2.0]hept-2-ene between the primary products bicyclo[2.2.1]hept-2-ene and cyclopentadiene plus ethene is 2:1. This and earlier stereochemical results permit the calculation of the partitioning of the [3.2.0] olefin between the orbital symmetry allowed [1,3] carbon shift-with-inversion product and several forbidden or non-concerted reaction channels (approximately 1:1) and the stereochemistry of the ethene d2 formed from exo,exo-[6,7-2H2]bicyclo[3.2.0]hept-2-ene directly (1:1 E: Z).
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020604
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  • 151
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    Switching of reaction pathways due to methylene chain length effects (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 187-204 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Reaction products of bifunctional chain molecules with structure X—(CH2)n—Y may critically depend on the chain length n. When the chain length is short (n ≤ 5), reaction products particular to an intramolecular reaction can be dominant, while a process corresponding to an intermolecular reaction between X—CH3 and H3C—Y may take place for higher homologues having large n (≥10). The reaction switching dependent on n is explained in terms of the encounter probability for both end groups (X and Y) with conformations pertinent to product formation. The reaction switching of this sort is discussed on the basis of a reactivity profile recorded as a function of the chain length. Similar reactivity profiles have been observed for thermal Friedel-Crafts cyclization and photo-Smiles rearrangement/photoredox reaction. It is anticipated that the magic methylene chain length of 7 may give rise to an appreciable decrease in reaction yields (e.g. ‘difficulty in medium-sized ring closure’) or an anomalous switching of reaction pathways due to chain length effects.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020302
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  • 152
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    Solute-solvent interactions in chemical and biological systems. IV. Correlations of ΔG, ΔH and TΔS of transfer of aliphatic and aromatic solutes from 2,2,4-trimethylpentane to aqueous solution (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 559-564 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: ΔG, ΔH and TΔS of transfer of 25 aliphatic and aromatic solutes from 2,2,4-trimethylpentane to aqueous buffer (pH 7) at 298 K have been examined in terms of intrinsic volumes and the solvatochromic parameters π*, δ, β and α of the pure solutes Correlations of the form \documentclass{article}\pagestyle{empty}\begin{document}$$ XYZ = XYZ_0 + {{mV_{\rm I} } \mathord{\left/ {\vphantom {{mV_{\rm I} } {100}}} \right. \kern-\nulldelimiterspace} {100}} + s\pi ^* + d\delta + d\beta + a\alpha $$\end{document} indicate that the thermodynamic quantities of transfer are unequally affected by solute properties; most notably, for aromatic solutes the cavity term mVI/100 is a principal (unfavorable) factor affecting TΔS, but has little effect on ΔH. Transfer to water is favored by increasing solute π* (dipolarity-polarizability), β (H-bond basicity) and α (H-bond acidity), because water has greater dipolarity, H-bond acidity and H-bond basicity than trimethylpentane. Hydrogen bonding contributes exothermically to ΔH, but unfavorably to TΔS, as would be expected from a loss of transitional entropy. Correlations of ΔG, ΔH and TΔS with solute VI/100, β, α, μ2 and polarizability function [(n2 - 1)/(n2 + 2)] give closely comparable results.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/poc.610020708
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    Masthead (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989) 
    Details
    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
    URL: http://dx.doi.org/10.1002/poc.610020801
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  • 154
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    Cation radical pericyclic reactions: CyclopropanationDedicated to Michael J. S. Dewar in the year of his seventieth birthday. (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 585-601 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Triarylaminium salts smoothly catalyze the cyclopropanation of dienes, styrenes and tetrasubstituted alkenes by ethyl diazoacetate. The reactions are regioselective and, in the case of additions to conjugated dienes, cyclopropane-periselective. A cation radical chain mechanism involving carbene transfer from ethyl diazoacetate to a substrate cation radical is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020802
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  • 155
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    Calorimetric study of the effect of N-methylation in azoles: Loss of an active centre of solvation (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 646-652 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Using a series of equations connecting experimental and theoretical values, it is possible to discuss the origin of the N-methylation effect in azoles dissolved in water and dimethyl sulphoxide. The existence in the azoles studied of a linear relationship between the gas → solution transfer enthalpies and the charge on the pyrrole hydrogen atom demonstrated the fundamental importance of the loss of an active centre for solvation. For the imidazole-N-methylimidazole pair, the complete thermochemical cycle has been determined, allowing the apparent lack of an effect of N-methylation on the basicity in solution to be discussed.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020807
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  • 156
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    Oxidation of substituted ethanols by sodium N-bromobenzenesulphonamide: A kinetic study (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 660-671 
    Details
    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 seven substituted ethanols by sodium N-bromobenzenesulphonamide or bromamine-B (BAB) in the presence of HCl was studied at 45 °C. The rate shows a first-order dependence on [BAB]0 and is fractional in [alcohol]0, [H+] and [Cl-]. Ionic strength variations, addition of benzenesulphonamide reaction product and variation of dielectric constant of the medium have no effect on the rate. The solvent isotope effect kH2O′/kD2O′ ≈ 0·97. The rates do not correlate satisfactorily with Taft's substituent constants. Activation parameters ΔH≠, ΔS≠, ΔG≠ and log A were calculated by studying the reaction at different temperatures (308-323 K). It was found that ΔH≠ and ΔS≠ are linearly related and an isokinetic relationship is observed with isokinetic temperature β = 393 K, indicating enthalpy as a controlling factor.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020809
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  • 157
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    Masthead (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989) 
    Details
    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
    URL: http://dx.doi.org/10.1002/poc.610020301
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  • 158
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    Masthead (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989) 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19893310101
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  • 159
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    Iminoformylierung substituierter Crotonnitrile. III. Zur Stereochemie und innermolekularen Beweglichkeit von 4-Amino-1,1-dicyanbuta-1,3-dienen7. Mitteilung über spektroskopische Untersuchungen an Butadienderivaten, 6. Mitteilung vgl. [3]. (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 1-10 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Iminoformylation Reaction of Substituted Crotonnitriles. III. Stereochemistry and Intramolecular Mobility of 4-Amino-1.1-dicyano-buta-1.3-dienes1H- and 13C-n.m.r. spectroscopic investigations show the preference of s-trans configuration and the push-pull character of the investigated 4-amino-1,1-dicyano-buta-1,3-dienes. Dynamic 1H- and 13C-n.m.r. data for the rotation process about the C—N bond are determined. The activation energies are discussed with respect to electronic and steric effects of substituents and to solvents polarity.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/prac.19893310102
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  • 160
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    On the Acetylation of Phenanthrene and 9-chlorophenanthrene (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 15-21 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Friedel-Crafts acetylation of phenanthrene (1a) in sym-tetrachloroethane yields mixtures of 2-, 3- and 9-acetylphenanthrenes (2a, 3a, 4). The distribution of isomers is found to depend strongly upon the method of mixing the reagents. Acetylation of 9-chlorophenanthrene (1b), performed by a variety of methods and solvents, led mainly to 3-acetyl-9-chlorophenanthrene (3b) (≥85%). Previously unreported 2-acetyl-9-chlorophenanthrene (2b) was found to form up to a maximum 11% in nitrobenzene.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19893310104
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  • 161
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    New syntheses of pyrazolo[3,4-d]pyrimidine, pyrazolo[3,4-d]pyridazine, isoindolinedione and pyrazole derivatives (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 31-36 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Phenacylmalononitriles 2 react with hydrazines, acetic-hydrochloric acid and with diazotised primary aromatic amines to afford phenacylpyrazole (5a,b), aminofurans (6a,b) and aminopyrazole derivatives (3a,d) respectively. The synthesised derivatives (3d, 6a) were the key materials for the synthesis of isoindolinedione, (7a-c) pyrazolopyrimidine (9, 10), and pyrazolopyridazine derivatives (11). The structures of the newly synthesised heterocycles were established on the basis of elemental analyses and spectral data besides synthesis via other routes.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/prac.19893310106
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    Substitution Reactions of 2-(Aroyl, Methylidene)-thiazolidine-4-on Derivatives (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 55-60 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of 2-(aroyl, methylidene)-3-arylthiazolidine-4-ones 1 with trifluoromethylsulfenyl chloride yields a mixture of geometric (Z, E) isomers of 2(aroyl, trifluorosulfenylmethylen)-3-aryl-thiazolidine-4-ones 2. The bromination of 1 leads to 2-(aroyl, methylidene)-3-aryl-5-bromothiazolidine-4-ones 3 which on reaction with nitrosobenzene formes nitrones 4. The structures of the compounds 2-4 were determined by means of n.m.r. and i.r. spectroscopy.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/prac.19893310109
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  • 163
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    Besonderheiten des Pyrolyseverhaltens von Isoalkylaromaten (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 61-68 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Special Features in Pyrolysis Behaviour of IsoalkylaromaticsThe pyrolysis of cumene, sec. butyl- and tert. butylbenzene proceeds in a laboratory scale quartz vessel in the temperature range 600-750°C. Conversion occurs mainly via a radical-chain mechanism in the side chain in proportions, determined by the dissociation energies of the C—C- and C—H-bonds. Dealkylation was observed in greater amounts than for n-alkylbenzenes. It is interpreted by H-atom addition to the aromatic nucleus, followed by β-scission to benzene and isoalkenes. It was be shown, that H-atoms are formed by unusual reactions such as neophyl rearrangement and homolytic rupture of C—C-bonds in the side chain.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/prac.19893310110
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  • 164
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    Preparation of 2-Aroyl-3-methyl-1H-1,4-benzothiazines. ESR Study of 2-benzoyl-1,3-dimethyl-1H-1,4-benzothiazine (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 82-88 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2-Aroyl-3-methyl-1 H-1,4-benzothiazine ylids (2a-k) were prepared by alkylation of the corresponding 4H-benzothiazines 1. The ylids 2 are labile at room temperature; proper analytical and 1H-n.m.r. data were obtained for their picrates. E.s.r. studies of u. v. irradiated polycrystalline form of (2; R1 = Me, R2 = H) gave evidence for a long-lived benzothiazinyl radical with the odd electron residing on nitrogen 6.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/prac.19893310113
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  • 165
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    Chinoxaline. XXVII.XXVI. Mitt.: [1] Synthese bis-azolo[a,c]kondensierter Chinoxaline. II. Darstellung aus 4-Formyl-azolo[a]chinoxalinenAus der Dissertation von M. VOGEL, Karl-Marx-Universität Leipzig, 1985.Herrn Prof. Dr. M. Weißenfels zum 60. Geburtstag gewidmet (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 75-81 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Quinoxalines. XXVII. Synthesis of Bis-azolo[a,c]-fused Quinoxalines. II. Synthesis from Azolo[a]quinoxaline-4-carbaldehydesThe azolo[a]quinoxaline-4-carbaldehydes 2a-d were obtained from 4-methyl azolo-[a]quinoxalines 1a-d by Kröhnke reaction. 2a exists in the hydrate form. 2a-d react with tosylhydrazide giving the thermally labile compounds 3a-d in good yields. Treatment of 3a-d with a boiling solution of sodium ethoxide (Bamford-Stevens reaction) leads to the fused quinoxaline systems 4a-d. 4d was also obtained from bis-tosylhydrazone 10.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/prac.19893310112
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  • 166
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    Failure of azo coupling by ion pairing of 4′-Diethylamino-α-cyano-stilbene-4-diazonium tetraphenylboranates in water (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 89-95 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The influence of chloride and five tetracoordinated boron anions on the light absorption and azo coupling of the 4′-diethylamino-α-cyano-stilbene-4-diazonium ion 1 in formamide, dimethylformamide and water, respectively, is reported. In highly diluted solutions, no ion pairing of 1 occurs in polar organic solvents. Except for tetraphenylboranates, this applies also to water. Here, tetraphenylboranates produce a large bathochromic shift of the intramolecular CT-band of 1 due to the formation of contact ion pairs. This ion pairing is strongly favoured by hydrophobic interaction between 1 and the complex anion.In contrast to the free diazonium 1, its ion pairs with tetraphenylboranates fail in azo coupling in water. This is shown on coupling with 2-naphthol.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/prac.19893310114
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  • 167
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    Zur σ-Akzeptorstärke von starken organischen Elektronenakzeptoren (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 96-104 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the σ-Acceptor Strength of Strong Organic Electron AcceptorsAcceptor numbers (AN) according to GUTMANN of various strong organic electron acceptors, such as TCNE, chloranile, C7H7⊕ or triphenylmethylium salts, have been obtained by means of complexation with Fe(phen)2(CN)2 in 1,2-dichloro-ethane and nitromethane. The AN of organic electron acceptors reflect the capability of a weak coordinative electrophilic attack upon nucleophilic compounds. Based on these results the influence of solvents upon CT-energy (ṽCT) in weak π-electron-donor-acceptor complexes is discussed. The blue shift of ṽCT depends on the donicity (D) of the solvent, which leads to linear correlations of ṽCT versus parameters of donicity. The sensitivity of solvatochromy depends on the AN of the acceptor. On the variation of the bπ-donor the sensitivity of solvatochromy in relation to the quotient dṽCT/dD is influenced. With the help of polarographic results can be demonstrated that the influence of solvents on ṽCT remarkably depends on the specific solvation in the ground state of the electron acceptor.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/prac.19893310115
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  • 168
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    Vinyloge Acylverbindungen. XXI. 1H-NMR-spektroskopische Untersuchungen an 3-Chlor-propen-iminiumsalzen (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 111-114 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Vinylogous Acyl Compounds. XXI. 1H-N.M.R. Spectroscopic Investigations on 3-Chloropropen-iminium SaltsThe 1H-n.m.r. data of a series of 3-aryl-3-chloropropeniminium salts 5 are reported. From the vicinal coupling constants 3J(H1, 2H) as well as from NOE difference spectra follows that salts of type 5 have throughout E(1,2)Z(2,3) configuration.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/prac.19893310117
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  • 169
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    Regio- and stereoselectivity of 1-(Pyridazin-3-yl)-3-oxidopyridinium Betaines towards 2π- and 4π-conjugated olefins (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 105-110 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1-(6-Phenyl) and 1-(6-(4-tolyl)-3-oxidopyridinium betaines (1a, b) react as 1,3-dipoles with conjugated olefines, namely 4-vinylpyridine, ethyl cinnamate and styrene as 2π-1,3-dipolarophiles to give 2,6-cycloadducts [6-substituted-8-azabicyclo[3,2,1]oct-3-en-2-ones (3a, b, 4a, b and 5b)] and with butadiene and furan as 4π-dipolarophiles to give 2,4-cycloadducts [7-substituted-7-azabicyclo[4,3,1]deca-3,8-diene-10-one] and 3-6-phenylpyridazin-3-yl)-3-aza-10-oxatricyclo-[5,2,1,12,6]undeca-4,8-diene-11-one (9a). Structural and configurational assignments were based on H.n.m.r. spectral analysis.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19893310116
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  • 170
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    Thiatriazole. V. Zur Reaktion von Isothiocyanaten mit 1,2,3,4-Thiatriazolderivaten (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 115-120 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thiatriazoles V. On the Reaction of Isothiocyanates with Thiatriazole DerivativesThe reaction of 1,2,3,4-thiatriazoles with alkyl and aryl isothiocyanate proceeded differently. Methylisothiocyanate furnished a 2:1 product with 5-amino-1,2,3,4-thiatriazole. Arylisothiocyanates reacted under the same conditions to the known thiapentalenes 6. 5-Alkyl- and 5-arylamino-1,2,3,4-thiatriazoles gave 5-substituted 1,2,4-thiadiazol-3-thions 8. Similar the hydrazones of 1,2,3,4-thiatriazole reacted with isothiocyanate to form the hydrazones of 1,2,4-thiadiazole-3-thione 10. 4-Dimethylamino-pyridine is a necessary catalyst for the selectivity of these reactions.
    Additional Material: 4 Tab.
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    URL: http://dx.doi.org/10.1002/prac.19893310118
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    N-Arylsulfonyl-N′-(pyrimidin-4-yl)ureasAcademy of Sciences of the GDR (F. ZEUNER and H.-J. NICLAS), DD 256863 (25th May, 1988).-synthesis and reaction with dimethyl sulfoxide (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 121-128 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The N-arylsulfonyl-N′-(pyrimidin-4-yl)ureas (3a-1) were synthesized by reaction of arylsulfonyl isocyanates (1) with 4-amino-2,6-dialkylpyrimidines (2). Treatment of 3 with alkali or of 1 with an excess of 4-amino-2,6-dimethylpyrimidine (2a) gave the salts 4a-e. Reaction of the ureas 3a-c with dimethyl sulfoxide at 90 to 120°C afforded N,N′-bis(2,6-dimethylpyrimidin-4-yl) ureas 8a-c. The reaction is assumed to involve a four-centre mechanism with 5 as intermediate.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19893310119
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  • 172
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    1H- und 13C-NMR-Spektren von N-Methyl-chinoliniumchalkonen: Bestimmung von σ-Konstanten für die 2-, 3- und 4-Position des N-Methyl-chinoliniumrings (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 129-135 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1H- and 13C-N.M.R. Spectra of N-Methyl-quinolinium Chalcones: Determination of σ-Constants for the 2-, 3- and 4-Position of the N-Methyl-quinolinium RingFor the N-methyl-quinolinium chalcones 1a-c the 1H- and 13C-n.m.r. data are reported. The unambiguous assignment of signals is based upon the 1H/1H homoshift and the 13C/1H heteroshift correlated 2D-n.m.r. spectra. Using a Hammett relationship we have determined σ-constants for the 2-, 3- and 4-position of the N-methyl-quinolinium ring from the 13C-α chemical shifts of 1a-c. Their comparison with the σ-values for the equivalent positions in the pyridine, N-methyl-pyridinium and quinoline ring indicates the additivity of anellation and quaternization effect.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19893310120
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  • 173
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    Dimethyl 4-oxobenzo[b]cyclooct-5-en[1,6-e]-1,4-thiazine-1,2-dicarboxylates - X-Ray Crystal Structure of the 2,2-Dimethyl Homologue (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 141-144 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19893310122
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    A simple synthesis of some novel N-Phosphorylated Formamidines (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 149-152 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19893310124
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    Application of trichloroethylene in organic syntheses. V. A Modified Synthesis of Dichloroacetylene (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 145-148 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19893310123
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    Cyclofunktionalisierung von 2-Allyl-phenolen mit Schwefelchloriden. III. 2-Arylthiomethyl-2,3-dihydrofuro[3,2-h]chinoline aus 7-Allyl- bzw. 7-Methallyl-8-hydroxychinolin und Aryl-sulfenylchloridenR. M. MUSLIN, Dissertation zur Promotion A. Mathematisch-Naturwissenschaftliche Fakultät der Karl-Marx-Universität, Leipzig 1985. (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 136-140 
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    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyclofunctionalization of 2-Allyl-phenols with Sulfur Chlorides. III. 2-Arylthiomethyl-2,3-dihydrofuro[3,2-h] quinolins from 7-Allyl- and 7-Methallyl-8-hydroxyquinoline, respectively, and Arylsulfenyl ChloridesReactions of 7-allyl- (3) and 7-methallyl-8-hydroxyquinoline (4) with selected arylsulfenyl chlorides (5a-d) yield the products of cyclofunctionalization corresponding 2-arylthiomethyl-2,3-dihydrofuro[3,2-h]quinolins (6 and 7). The products are identified by 1H-n.m.r.-spectroscopy, mass spectrometry and microanalyses.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/prac.19893310121
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    Coordination Complexes of Fe(III) with Schiff bases derived from sulphonamide drugs (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 157-161 
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    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19893310126
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    Funktionalisierte N-Acylformamidiniumsalze und -formamide als Acylierungs- bzw. Iminoformylierungsmittel für semicyclische Amidine und spezielle AmineXIII. Mitteilung über Nitril-Formamidchlorid-Addukte; XII. Mitteilung siehe [1]. (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 153-156 
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    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Functionalised N-Acylformamidinium Salts and Formamides as Acylating or Iminoformylating Reagents for Semicyclic Amidines and Special Amines
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/prac.19893310125
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    Substituenteneffekte in den 13C-NMR-Spektren von diastereomeren Chalkondihalogeniden. VII. Untersuchungen an erythro-Chalkoniodchloriden (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 162-166 
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    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Substituent Effects in 13C-N.M.R. Spectra of Diastereomeric Chalcone Dihalogenides. VII. Investigations of erythro-Chalcone Iodochlorides
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/prac.19893310127
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    Synthese von 3-(2-Oxopropyl)-oxazolo[4,5-b]pyridin-2-on und seine Reaktion mit Hydroxylaminhydrochlorid bzw. primären Aminen (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 167-170 
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    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of 3-(2-Oxopropyl)-oxazolo[4,5-b]pyridin-2-one and its Interaction with Hydroxylamine Hydrochloride and Primary Amines
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/prac.19893310128
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    Conformational influences on the liquid-crystalline state of 1,4-disubstituted cyclohexanes. II. Applied Model Studies (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 171-174 
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    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19893310129
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    Eberson, L.: Electron transfer reactions in organic chemistry. 234 S., 65 Abb., 32 Tab., 17 × 25 cm. Berlin, Heidelberg, New York, London, Paris, Tokyo: Springer-Verlag 1987. (Reactivity and Structure. Concepts in Organic Chemistry, Vol. 25). Leinen, 128,-DM (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 175-176 
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    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19893310130
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    Masthead (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989) 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19893310201
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    Sachse, H. und Mohr, E.: Zur Konformation des Cyclohexans. Hrsg. D. Goetz, I. Jahn, E. Wächter, H. Wußing. 152 S., 58 Abb., 2 Tab., 19 × 12 cm. Leipzig: Akademische Verlagsgesellschaft Geest & Portig K.-G. 1987. (Ostwalds Klassiker der exakten Wissenschaften) broschürt, 21, 00 M (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 176-176 
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    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19893310131
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    Studies of tertiary amine oxides. 11. Rearrangement of Acetylenic Amine Oxides (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 187-194 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sixteen acetylenic amine oxides (5a-p) were prepared by the oxidation of the corresponding tertiary amines (4a-p) with m-chloroperbenzoic acid. The N-oxides are thermally unstable and undergo a rearrangement when stirred in an inert solvent yielding O-allenyl hydroxylamines (6). The rearrangement proceeds by an intramolecular cyclic mechanism.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19893310203
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  • 186
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    Franck, H.-G.; Stadelhofer, J. W.: Industrielle Aromatenchemie, Rohstoffe - Verfahren - Produkte. 504S., 201 Abb., 92 Tab., 16 × 24 cm. Berlin, Heidelberg, New York, London, Paris, Tokyo: Springer-Verlag 1987. Pappe, 128,- DM (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 194-194 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19893310204
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  • 187
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    Photochemie von Acylaziden. III. Direkte und sensibilisierte Photolyse von p-Trimethylsilylbenzoylazid in fluider Phase und in polymeren Schichten (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 177-186 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photochemistry of Acylazides. III. Direct and Sensitized Photolysis of p-Trimethylsilylbenzoylazide in the Fluid Phase and in Polymeric LayersThe photochemistry of the title compound in cyclohexane was investigated by direct and sensitized excitation, respectively. The only products which could be detected by means of HPLC were the rearrangement product isocyanate from the singlet azide and the insertion product into the solvent via the singlet nitrene, respectively. Products via the triplet states were not formed by direct photolysis. The generally high quantum yields of the photolysis of the acylazide 1 are strongly dependent on the concentration. At 0.1 M the quantum yield amounts to 4.The photolysis was sensitized by several triplet generators creating the abstraction products as main products. But also insertion products were formed via the triplet azide. From the results a triplet ground state of the nitrene is postulated. The sensitization can be realized also by electron donors like diphenylanthracene, pyrene or perylene. An electron transfer to 1 is assumed. The products of this sensitization are the same as via the direct photolysis.The results in solutions can be applied to polymers. The modification of polymers (silylation by the nitrene formed) is possible in this way.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19893310202
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  • 188
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    Flavyliumsalze als Sonden zur Charakterisierung anionischer Tensidlösungen (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 195-206 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Flavylium Salts as Probes for the Characterization of Anionic MicellesFlavylium salts are suitable probe molecules for the fluorimetric investigation of the critical micelle concentration (CMC); for the absorption-spectroscopic investigation of the surface potential; and also the microacidity in the Stern-layer of anionic micelles. The reaction rates of the hydrolytic cleavage of the 7-hydroxy-4′-methoxyflavyliumion 1a and the equilibrium between 1a and the 2,4-dihydroxy-4′-methoxychalcone 5a formed were studied in acidic water solutions and in micellar surfactant solutions. Both measurements resulted in comparable values of the microacidity on the surface of the sodium dodecylsulfate micelles (SDS). The calculated surface-potential of SDS-micelles corresponds to literature data.The surface-potentials of p-dialkylbenzenesulfonate micelles (p-DABS) depend on the structure of these surfactants in a characteristic manner.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19893310205
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  • 189
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    Hesse, M.; Meier, H.; Zeeh, B.: Spektroskopisehe Methoden in der organischen Chemie. 3. über-arb. Aufl. VIII, 318 S., 199 Abb., 94 Tab., 19,3 × 23,8 cm. Stuttgart, New York: G. Thieme Verlag 1987. Kartoniert, 49,80 DM (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 211-211 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19893310207
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  • 190
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    Reactions with substituted acrylonitriles: A novel Synthesis of Polysubstituted Pyrimidines (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 207-211 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 3-Arylacrylonitrile-2-thiocarboxamides (1a-d) reacted with S-methylisothiourea to give 4-amino-6-aryl-2-methylmercaptopyrimidine-5-carbonitriles (3a-d). The products 3a-d were also obtained via the reaction of 3-arylacrylonitrile-2-carbonitriles (4a-d) with S-methylisothiourea. Compounds 4a-d reacted with thiourea and urea to yield 4-amino-6-aryl-2-mercaptopyrimidine-5-carbonitriles (5a-d) and 2-hydroxy derivatives (5e-h) respectively. Oxidation of 5a-d with hydrogen peroxide afforded 5e-h. 5a-h were readily alkylated with methyl iodide to give 3a-d.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19893310206
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  • 191
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    Substituenteneffekte in den 13C-NMR-Spektren von diastereomeren Chalkondihalogeniden. VIII. Untersuchungen an α- und β-Halogendihydrochalkonen und Berechnung von 13C-chemischen Verschiebungen bei diastereomeren Chalkondihalogeniden und Chalkonhalogenhydrinen (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 212-222 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Substituent Effects in 13C-N.M.R. Spectra of Diastereomeric Chalcone Dihalogenides. VIII. Investigations of α- and β-Halogene Dihydrochalcones and Calculation of 13C-chemical Shifts of Diastereomeric Chalcone Dihalogenides and Chalcone HalogenohydrinsThe chemical shifts of C-α and C-β in the 13C-n.m.r. spectra are determined and compared with calculated values from an incremental system and Taft relationship. The correlations are extended for erythro and threo isomers of halohydrins and diastereometric dihalogenides 6-18.The chemical shifts of C-α and C-β atoms of 6-18 are described in the dependence of the shifts calculated by an incremental system. Excellent correlations allowed the computation of chemical shifts of C-α and C-β for diastereomeric α,β-disubstituted dihydrochalcone derivatives likely 6-18 in advance.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19893310208
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  • 192
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    A novel efficient approach to the Synthesis of 6-Oxo Ethinylestradiol and its 3-isopropanesulfonateSteroids 24.; Steroids 23.: [1]Part of this publication was presented as a poster at the 11th Conference on Isoprenoids in Jachranka (Poland), September, 1985. (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 223-230 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ethinylestradiol (1) was converted into the corresponding 6-oxo derivative 7 by a short and simple procedure involving acetate 10 and ketone 11. Phase transfer catalyzed esterification of compound 7 with propane-2-sulfonyl chloride gave sulfonate 12.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19893310209
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  • 193
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    Dithiocarbonsäuren, Dithiocarbonsäureester oder Thiocarbonsäureamide aus methylenaktiven Chlormethylverbindungen und Schwefel (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 243-262 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dithiocarboxylic Acids, Dithiocarboxylic Esters, or Thiocarboxylic Amides by Reaction of Methylene-active Chloromethyl Compounds with SulfurWith a mixture of sulfur and amine in DMF at room temperature halomethyl compounds (1, 5-10) can be oxidized to give thiocarboxylic acids (2, 11-16) and their derivatives (3, 4, 17-35). We studied this reaction in detail especially with chloroacetic derivatives (11-15) or chloromethyl heterocycles (16) formally derived from chloroacetic acid.The resulting thiooxalic acid derivatives (11-27) represent activated acids and very useful C2-synthons, especially for the synthesis of heterocycles.Oxidation in the presence of triethyl amine leads to dithiocarboxylates (11-16) which can be alkylated to dithioesters (17-27) in high yields.As a rule, with different primary and secondary amines instead of tertiary amines these dithiocarboxylates or dithiocarboxylic esters can be transformed already at low temperatures to thioamides (28-35).
    Additional Material: 14 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19893310211
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  • 194
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    Oxidative dimerization of 4-Alkyl-6-phenyl-2,3-dihydrooxazines (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 263-266 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction mixtures containing 4-methyl-(or ethyl-)-6-phenyl-2,3-dihydrooxazine kept for some weeks in contact with air at room temperature yielded products of oxidative dimerization (dimorpholinofurans). The structures of the new compounds were determined on the basis of spectral studies and chemical transformations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19893310212
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  • 195
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    Phase transfer catalysed alkylation of enamines of β-keto carbothionic acid anilides with dihalogenoalkanes: Synthesis of Cyclic S,N-Acetals of α-Oxo Ketene (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 231-242 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Alkylation of 2-morpholino-cycloalken-1-carbothionic acid anilides 1 and 2 with 1,3-dibromopropane in a two-phase system leads to 1-morpholino-cycloalken-3-aryl-tetrahydro-1,3-thiazine-2-ylidene 3 and 4. Reactions of 2-morpholino-cyclopenten-1-carbothionic acid anilides 5 and 3-morpholinothiocinnamic acid anilides 8 with 1,2-dibromoethane yield 1-morpholino-cyclopenten-3-aryl-thiazolidine-2-ylidene 7 and 2-(2′-phenyl-2′-oxo-ethylidene-3-aryl)thiazolidine 9, respectively. Alkylation of 1-indanone- and 1-tetralone-2-carbothionic acid anilides 11 and 12 with dihalogenoalkanes yield 1-oxo-indanylidene- and 1-oxo-tetralidenethiazolidines 14, 16 and tetrahydro-1,3-thiazines 15, 17, respectively.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19893310210
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  • 196
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    Hydropyrene, alicyclische Modellverbindungen für GC-MS-Untersuchungen (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 267-272 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hydropyrenes, Alicyclic Model Compounds for GC-MS InvestigationsHydrogenation of asymmetric and symmetric hexahydropyrene gives the five possible aromatic decahydropyrenes via different octahydropyrenes. From these compounds some dodecahydro- and tetradecahydro-pyrenes, the four isomers of perhydropyrene with chair conformations and five new stereoisomers with twist boat six-membered rings are obtained. The configurations of the hydrogenated pyrenes are assigned using chromatographic retention indices and mass spectrometric fragmentation in combination with force field calculations.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19893310213
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  • 197
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    Studies on the oxidation of enamines with molecular oxygen. I. Oxidation of Some Piperidino Alkenes (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 285-292 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the autoxidation of 1-piperidinocyclohex-1-ene (1), 1-piperidinobut-1-ene (2), 3-piperidinopent-2-ene (3), and 1-piperidino-2-methyl-prop-1-ene(4) only products of an oxidative attack at the C=C-double bond are formed.Both α-aminoketones, the products of the rearrangement of primarily formed epoxides, and products of the oxidative session of the C=C double bond are obtained. As a side reaction some hydrolysis of the starting enamines takes place. This hydrolysis proves that some water must be formed during the enamine oxidation.
    Additional Material: 7 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19893310215
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  • 198
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    Studies on the Thermal Conversion of Long-chain Alkynes at high temperatures in the gas phaseHerrn Professor Dr. Manfred Mühlstädt zum 60. Geburtstag gewidmet (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 273-284 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the gas phase pyrolysis of long-chain alkynes C5 to C9 at 773 to 873 K, a remarkable portion of molecular reaction (retro-ene analogous decompositions as well as cycloisomerizations of the parent alkynes to cyclopentenes alkylated in 3-position) takes place besides the thermal conversion of the starting compounds via radical chain processes. The different products were separated by GC and the main products identified by means of different methods. The mechanisms of formation of the major products are discussed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19893310214
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  • 199
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    Pyryliumverbindungen. 41. 7aH-Cyclopenta[b]pyran-7-one durch Ringtransformation von 2,4,6-Triaryl-pyryliumsalzen mit acyclischen 1,2-Diketonen (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 293-305 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pyrylium Compounds. 41. 7aH-Cyclopenta[b]pyran-7-ones by Ring Transformation of 2,4,6-Triarylpyrylium Salts with Acyclic 1,2-DiketonesReaction of 2,4,6-triarylpyrylium salts 1 with acyclic 1,2-diketones 2 (CH3COCOR, R = Me, Ph) in the presence of an appropriate condensing agent (e.g. piperidine acetate, triethyl-amine/acetic acid, sodium acetate) yields the hitherto unknown 2,4,5,7a-substituted 7aH-cyclopenta[b]pyran-7-ones 3 as a result of a new type of ring transformation (2,5-[C4O+C]/2,3-[C2+C3]). A characteristic feature of compounds 3 is their ability to undergo electrophilic substitutions. Thus, stepwise bromination of the 7a-methyl derivative 3a in acetic acid affords 6-bromo-7a-methyl-2,4,5-triphenyl-cyclopenta[b]pyran-7-one (4) and 3,6-dibromo-7a-methyl-2,4,5-triphenyl-cyclopenta[b]pyran-7-one (5); analogously, nitration of 3a leads to 7a-methyl-6-nitro-2,4,5-triphenyl-cyclopenta[b]pyran-7-one (6), indicating that position 6 is the favoured position for electrophilic substitutions. Contrary to the 3,5-unsubstituted pyrylium salts 1, the 3,5-dimethyl-2,4,6-triphenyl-pyrylium perchlorate (13) reacts with 1,2-diketones 2 through a 2,6-[C5+C] transformation to give arylsubstituted 1,2-diones 14. The structure of the new compounds was determined by spectroscopic methods and by a single crystal X-ray analysis of the dibromo derivative 5.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19893310216
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  • 200
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    New Red Diazonium Compounds based on 2-amino benzene diazonium salts (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 319-323 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using PMO theory the influence of substituents on the visible spectra of benzene diazonium salts is discussed. The theory explains the experimental structure-colour relationships and allows to predict new basic structures of coloured benzene diazonium salts. The synthesis and spectral behaviour of the new class of superfast diazonium salts are described.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19893310218
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