The reactivity of a,b-unsaturated carboxylic acids. Part XVI. The kinetics of the reaction of cycloalkenylcarboxylic and cycloalkenylacetic acids with diazodiphenylmethane in various alcohols

Abstract

The rate constants for the reaction of diazodiphenylmethane with 1-cyclopentenecarboxylic, 1-cycloheptenecarboxylic, cyclopent-1-enylacetic and cyclohept-1-enylacetic acids were determined in eight alcohols at 30°C using the appropriate UV-spectroscopic method. In order to explain the kinetic results through solvent effects, the second order rate constants of the examined acids were correlated using a total solvatochromic equation, of the form: log k = Ao + sp* + aa + bb, where p* is a measure of the solvent polarity, b represents the scale of solvent hydrogen bond acceptor basicities and a represents the scale of solvent hydrogen bond donor acidities. The correlations of the kinetic data were carried out by means of multiple linear regression analysis. The opposite sings of the electrophilic and the nucleophilic parameters are in agreement with the well-known reaction mechanism. The results presented in this paper were compared with the kinetic data for 1-cyclohexenecarboxylic and cyclohex-1-enylacetic acids obtained under the same experimental conditions.

Keywords

• cycloalkenecarboxylic acids
• cycloalkenylacetic acids
• diazodiphenyl-methane
• kinetic measurements
• protic solvents