Bisphenol a synthesis: Kinetics of the phenol‐acetone condensation reaction catalyzed by sulfonic acid resin

The industrially important reaction of phenol and acetone to give bisphenol A and water was catalyzed by beads of ion‐exchange resin (sulfonated styrene‐divinylbenzene copolymer) suspended in a batch reactor containing liquid reactants. The data are summarized by a rate equation accounting for reaction in the resin competitively swollen by water, acetone, phenol, and methylcyclohexane. The catalyst is modeled as two phases, each in equilibrium with the liquid: a polar phase consisting of sulfonic acid groups with hydrogeb–nonded acetone and water and a nonpolar phase consisting of the hydrocarbon matrix swollen with organic components. The rate determining step is the electrophilic attack on phenol in the nonpolar phase by a carbonium ion intermediate in the polar phase. Resin cross‐linked with 4% divinylbenzene initially catalyzed acetone conversion at a rate of 5 × 10−4 (moles)/(equiv of acid groups s) at 364°K. An 8% cross‐linked resin was much less active because the rigid polymer matrix was only slightly swollen by phenol, but a more highly cross‐linked resin with macropores and accessible internal surface catalyzed reaction almost as rapidly as the 4% cross‐linked catalyst.