Effect of binary aqueous‐organic solvents on the reaction of phenacyl bromide with nitrobenzoic acid(s) in the presence of triethylamine

Second‐order rate constants (k₂) of the reaction between phenacyl bromide and equimolar mixture of nitrobenzoic acid(s)–triethylamine have been determined in dimethylformamide (DMF)/acetonitrile (ACN)/acetone and aqueous mixtures of these solvents by conductometric method at 30°C. The rates of nitrobenzoic acids are found to be in the order: 4‐NO₂ > 3‐NO₂ > 3,5‐(NO₂)₂. Changes in the rate just by the addition of water (1% (v/v)) into organic component is rationalized. Decrease in the values of k₂ on increasing water content in organic solvent is explained on the basis of preferential solvation phenomenon. Single and dual regression analysis using the various solvent parameters of aqueous mixtures (E_T(30), Z, π*, β, α, and Y) resulted in π* and α as the best parameters to explain solvation of nitrobenzoates. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 401–409, 2004