Polystyrene sulfonic acid esters as alkylating agents: Preparation of unsymmetrical secondary amines

Spherical beads (210-290 μ) of styrene-divinyl benzene (10%) copolymer have been chlorosulfonated and reacted with alcohols to give corresponding sulfonate esters. Their reactions with primary amines, i.e. propyl amine and aniline, give the corresponding secondary amines in reasonable yields (67-76%). The resulting secondary amines are obtained by a simple filtration and distillation. Regeneration of the polymeric support can readily be achieved by acidification and subsequent reaction with thionyl chloride. The present method offers an alternative procedure for the preparation of unsymmetrical secondary amines.