Application of ionic liquids as recyclable green catalysts for selective alkylation of phenol

Alkylation of phenol with tert-butyl alcohol (TBA) as an alkylating agent was studied in presence of different ionic liquid catalysts. The synthesized ionic liquid catalysts were characterized by 1H NMR and TGA. It was proved that heteropoly anion-based ionic liquid catalyst is potentially promising candidates in production of 2,4-di-tert-butylphenol (2,4-DTBP) and 2,6-di-tert-butylphenol (2,6-DTBP) with high activity and selectivity. Maximum phenol conversion of 93% was achieved at the molar ratio of phenol:TBA:IL is 1:2:1, reaction time of 3 h and reaction temperature of 80 °C with 2,4-DTBP and 2,6-DTBP selectivity of 48 and 41%, respectively.