Liquid–liquid–liquid phase-transfer catalysis for cleaner and selective etherification of p-hydroxy-biphenyl with benzyl chloride to 1,1′-biphenyl-4-(phenylmethoxy)

Abstract

Conversion of bi-liquid phase transfer catalysis (PTC) into a tri-liquid PTC system presents several advantages in terms of enhancement of reaction rates and selectivity. These improvements lead to a minimization of waste, reduction in reactor volume and processing times by orders of magnitude in comparison with a liquid–liquid PTC process. The O-alkylation (etherification) of 4-hydroxybiphenyl with benzyl chloride to 1,1′-biphenyl-4-(phenylmethoxy) was carried out under L-L-L PTC system with 100% selectivity at 50°C. The resulting product is commercially used in fine chemical industry and to produce novel materials. The catalyst-rich third phase can be recycled many times, thereby leading to profitability and waste minimization. A reaction mechanism and kinetic model are developed and validated against experimental data, which include the effect of different variables on reaction rates and selectivity.