Kinetics and mechanism study of aniline addition to ethyl propiolate

Abstract

The kinetics of the addition reaction of aniline to ethyl propiolate in dimethylsulfoxide (DMSO) as solvent was studied. Initial rate method was used to determine the order of the reaction with respect to the reactants, and pseudo-first-order method was used to calculate the rate constant. This reaction was monitored by UV-Vis spectrophotometer at 399 nm by the variable time method. On the basis of the experimental results, the Arrhenius equation for this reaction was obtained as log k = 6.07 - (12.96/2.303RT). The activation parameters, Ea ΔH#, ΔG#, and ΔS# at 300 K were 12.96, 13.55, 23.31 kcal mol-1 and -32.76 cal mol-1 K-1, respectively. The results revealed a first-order reaction with respect to both aniline and ethyl propiolate. In addition, based on the experimental results and using also density functional theory (DFT) at B3LYP/6-31G* level, a mechanism for this reaction was proposed. © 2005 Wiley Periodicals, Inc.