Determination and interpretation of second order rate constants for the addition of hydrogen halides to alkenes

Abstract

An extensive range of second order rate constants for the addition of hydrogen halides to alkenes in 98% v/v ethanoic acid (acetic acid)–water have been obtained by conductivity measurements. The rate constants are in the expected order of HF < HCl < HBr < HI. The rates with different alkenes cannot be rationalised solely by a consideration of carbocation stability and it has been necessary to consider steric effects in order to explain the observed order.