PROCESS FOR PREPARING EXTRA PURE 2, 6-DIISOPROPYL PHENOL

摘要

Disclosed herein is a process for the preparation of highly pure 2,6-diisopropyl phenol (Formula I), which comprises reacting p-hydroxy benzoic acid (Formula II) with an alkylating agent in presence of aq. mineral acid followed by basification and subsequent washings to yield 4-hydroxy-3,5-diisopropylbenzoic acid (Formula III) free of dimer impurity, 4,4'-oxydibenzoic acid of Formula IV, ether impurity 3,5-di(propan-2-yl)-4-(propan-2-yloxy)benzoic acid of Formula V and the monoalkylated impurity 4-hydroxy-3-(propan-2-yl)benzoic acid of Formula VI; and decarboxylating 4-hydroxy-3,5-diisopropylbenzoic acid (Formula III) in presence of high boiling solvent and sodium hydroxide as a catalyst at high temperature to yield 2,6-diisopropyl phenol substantially free of ether impurity 1,3-di(propan-2-yl)-2-(propan-2-yloxy)benzene of Formula VII and monoalkylated phenol impurity 2-(propan-2-yl) phenol of Formula VIII. Propofol prepared by the process of the present invention is suitable for pharmaceutical use.