Sulfonation studies of monoisomeric di‐ and trialkylbenzenes

Abstract

AbstractSulfonation studies were conducted on a series of monoisomerically pure di‐ and trialkylbenzenes in order to determine the regioselectivity of sulfonation and how the selectivity varies with structural changes. Sulfur trioxide, because of its commerical significance, was investigated as the primary sulfonating agent. Lewis base adducts of sulfur trioxide and other sulfonating agents were also investigated for comparison. The studies demonstrated, in a quantitative manner, the tendency of the sulfonation to occur para to alkyl substituents. In one class of the alkylbenzenes investigated, 1,3,4‐alkyl dimethylbenzene, the sulfonation which occurred at the position para to the 3‐methyl group ranged in selectivity from 87–99%, even though this position, which is ortho to the larger alkyl group, was much less favorable from steric considerations than the position ortho to the 4‐methyl group. The determination of the position of sulfonation by a combination of nuclear magnetic resonance and high pressure liquid chromatographic techniques is discussed.