Hindered rotation in ortho-bis(dichloromethyl)benzenes

Abstract

A study of internal rotation in ortho-bis(dichloromethyl)benzenes by 1H n.m.r. spectroscopy shows the presence of locked conformers on the n.m.r. time scale when these substituents are flanked on one or both sides by chlorine of additional dichloromethyl groups, and that in cases where a chlorine is substituted on both sides of two ortho-bis(dichloromethyl)groups ΔG‡ at Tc is 17·4–17·7 kcal mol–1.