Alkylation of biphenyl with propene on HNa-mordenite

Abstract Alkylation of biphenyl with propene to produce 4,4′-diisopropylbiphenyl (4,4′-DIPB) was investigated using silica-alumina and zeolites such as faujasite Y, beta, offretite, mordenite, ZSM-8, and ZSM-5 as catalysts. Of these, mordenite was the most active and selective to 4,4′-DIPB. The highest yield of 4,4′-DIPB was obtained when 55% of the sodium cations of mordenite were exchanged with protons. Propene was selectively consumed by alkylation on this mordenite, while undesirable side reactions of propene occurred if the level of proton exchange was higher. The 4,4′-DIPB produced was isomerized to thermodynamically more favorable isomers, although the isomerization was remarkably suppressed on HNa-mordenite. These results can be understood by taking the acid strength into consideration.