AbstractThe rate constants for the reaction of different cycloalkenylcarboxylic, cycloalkenylacetic acids, and phenylacetic acid with diazodiphenylmethane were determined in 12 aprotic solvents at 30°C. In order to explain the kinetic results through solvent effects, the second‐order rate constant of the examined acids was correlated using the Kamlet–Taft solvatochromic equation. The correlations of the kinetic data were carried out by means of multiple linear regression analysis, and the solvent effects on the reaction rates were analyzed in terms of initial and transition state contributions. The opposite signs of the electrophilic and the nucleophilic parameters are in agreement with the well‐known mechanism of the reaction of carboxylic acids with diazodiphenylmethane. The quantitative relationship between the molecular structure and the chemical reactivity is also discussed. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 361–367, 2005