Tert-butylation of phenol over Hβ, HY, HZSM-5 and HAlMCM-41

Tert-butylation of phenol with different alkylating agents, i.e., iso-butylene, MTBE and tert-butyl alcohol (TBA), was studied over various molecular sieve catalysts. It revealed that the reactivity followed the order of Hβ > HY > HZSM-5 ≈ HAlMCM-41 in the catalysts and of iso-butylene > MTBE > TBA in the alkylating agents. The selectivity of the product depended not only on the nature of the catalysts but also on the reaction conditions. p-TBP is a more favorable primary product than o-TBP owing to its less steric hindrance in the transition state, and the amount of o-TBP is always trace in the product. o-TBP may play a less important role than p-TBP in the formation of 2,4-DTBP.