Kinetic and product analytical study of the effect of substituents upon the solvolysis of benzyl azoxytosylate in aqueous trifluoroethanol - PhDData

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Kinetic and product analytical study of the effect of substituents upon the solvolysis of benzyl azoxytosylate in aqueous trifluoroethanol

The thesis was published by Gordon, Isobel M, in September 2022, University of Stirling.

Abstract:

Six variously substituted benzyl azoxytosylates, ((1) a: X=4-OCH3, 4-CH3, S-CH3, H, 4-CI, S-CI; Y=4-CH3) three 4-methylbenzyl 4-substituted-azoxyarenesulphonates, ((1) b: X=4-CH3; Y=CW, Br, OCH3), three 3-chlorobenzyl 4-substituted-azoxyarenesulphonates, ((1) c: X=3-CI; Y=CW. Br, OCH3) and three 3-chlorobenzyl 4-substituted-arenesulphonates, ((2): X=3-C1; Z=CW, Br, OCH3) have been prepared, and the rates and activation parameters of their solvolysis in 1:1 v/v aqueous 2,2,2-trifluoroethanol studied. For each series of compounds k28°c ¬has been correlated with v or v¬- in a Hammett-type study and the following p-values were obtained1- (1)a: p(r+) = -S.27, r > 0.999; (1)b: p(σ) = +1.37, r > 0.999. Using these p-values, it has been established, that, in the transition state of the solvolysis of (1), the cleavage of bonds (a) and (b) is concerted. In addition, from the relative magnitude of the p-values, the position of the transition state on the reaction map has been deduced. The unusual correlation of compounds (1)c with v- (p is positive) is discussed in terms of resonance stabalisation of the ground state by electron withdrawing substituents. Product analyses (some of a preliminary nature) have been carried out of the solvolysis of (1)a: X= 4-CH3, 4-OCH3, 3-CI and the arenesulphonates, (2).



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