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 basilication and subsequent washings to yield 4-hydroxy-3,5-diisopropylbenzoic acid (Formula III) free of dimer impurity, 4, 4′-oxy-dibenzoic 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.
本文揭示了一种制备高纯度
2,6-二异丙基酚(式I)的方法,包括在
水矿酸存在下,用烷基化剂使
对羟基苯甲酸(式II)反应,然后进行碱化和后续洗涤,以得到不含二聚体杂质、
4-羟基-3,5-
二异丙基苯甲酸(式III)、醚杂质3,5-二(异丙基)-4-(异丙氧基)
苯甲酸(式V)和单烷基化杂质
4-羟基-3-(异丙基)
苯甲酸(式VI);在高沸点溶剂和
氢氧化钠催化剂存在下,在高温下脱羧
4-羟基-3,5-
二异丙基苯甲酸(式III),以得到基本不含醚杂质1,3-二(异丙基)-2-(异丙氧基)苯(式VII)和单烷基化
酚杂质2-(异丙基)
酚(式VIII)的
2,6-二异丙基酚。由本发明方法制备的
丙泊酚适用于制药用途。