The LFER correlations for S_N2 reactions of phenacyl bromide

Abstract

The second order rate constants for the reaction of phenacyl bromide with a number of nucleophiles, viz., CO<img src='http://www.niscair.res.in/jinfo/three.gif' border=0>, HCO<img src='/image/spc_char/3_bar.gif' border=0>, OH^-, CH₃COO^-, N_3-, SO<img src='http://www.niscair.res.in/jinfo/four1.gif' border=0>, phenoxide, imidazole, pyridine, aniline and thiourea have been measured in 60% acetone - 40% water(v/v)solvent medium at different temperatures. The correlation of the rate data with different linear free energy relations (LFER), viz., the Bronsted equation, the Swain-Scott equation and the Edwards equation has been attempted. The applicability of Bronsted equation and Swain-Scott equation has been found to be unsatisfactory and the reasons are discussed. The correlation with Edwards equation has been found to be quite good as evidenced from the multiple regression analysis of the data which yielded the values α = 1.48 and β = 0.439 (<i>R</i>²= 89.7%). The activation parameters for all the reactions have been calculated and presented.