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  • 1
    Electronic Resource
    Electronic Resource
    Kinetic studies on the aminolysis of 1-(trimethylsilyl)ethyl arenesulphonates in acetonitrile and methanol (1994)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 7 (1994), S. 359-363 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Nucleophilic substitution reactions of 1-(trimethylsilyl)ethyl arenesulphonates with anilines and benzylamines in acetonitrile and methanol at 65·0°C were studied. The cross-interaction constants, ρXZ, between substituents in the nucleophile (X) and leaving group (Z) are relatively small (0·10 for XC6H4NH2 in MeCN) but similar to those for other SN2 processes at a secondary carbon atom. This provides further evidence for an approximately constant, loose SN2 transition state at a secondary carbon regardless of the size of the Cα substituent. The transition-state variations with substituents X and Z are in accord with that expected from the positive ρXZ value observed: a stronger nucleophile and/or nucleofuge leads to an earlier transition state, i.e. a lower degree of bond making and breaking.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610070705
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Nucleophilic substitution reactions of methallyl arenesulphonates with anilines and N, N-dimethylanilines (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 731-735 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Kinetic studies of the reactions of methallyl arenesulphonates (II) with anilines and N,N-dimethylanilines in acetonitrile at 45.0°C are reported. The sign and magnitude of the cross-interaction constants pxz (and βxz) between substituents in the nucleophile (X) and leaving group (Z) suggest that the transition state (TS) is slightly tighter than that for the corresponding reactions of allyl arenesulphonates (I). This is also supported by the observation that the magnitudes of ρx and ρz for II are uniformly greater than those for the reactions of I. These results are in line with the simple MO theory that the 2-position of the allyl system is inactive electronically. The steric effect of the 2-methyl group in II causes a rate retardation and a shift of the TS toward a later position along the reaction coordinate with a slight increase in the overall tightness of the TS structure. The large |ρxz| value obtained eliminates the possibility of an SN2′ mechanism.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610051104
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Aminolysis of aryl dithio-2-thiophenates and dithio-2-furoates in acetonitrile (1998)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 30 (1998), S. 849-857 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The aminolyses of the title substrates with anilines and benzylamines are investigated in acetonitrile. A clean second-order kinetics is obtained with a first-order rate law in the amine concentration, which is uncomplicated by the fast proton transfer step. The large magnitude of ρZ (ρ1g) as well as ρX (ρnuc) together with relatively large positive ρXZ values is consistent with a stepwise mechanism in which thiophenolate ion expulsion from the intermediate is rate limiting. For the reactions of aryl dithio-2-thiophenates with benzylamines the magnitude of ρX and ρZ values is relatively smaller suggesting that both the addition and expulsion of thiophenolate are partially rate determining. Relatively large secondary kinetic isotope effects, kH/kD≥1.7, with deuterated nucleophiles, support involvement a concurrent proton transfer to the departing thiophenolate ion in the transition state. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet 30: 849-857, 1998
    Additional Material: 7 Tab.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
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