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现在所有已知的合成苯佐卡因(1,对氨基苯甲酸乙酯)方法中,初始原料采用廉价而易得的对硝基苯甲酸(2),以乙醇进行酯化,然后以不同的方法还原对硝基苯甲酸乙酯(3)。主要缺点是在2酯化时需要大大过量的乙醇,回收乙醇困难,3的分离和精制操作时间长且繁杂。在生产条件下,回收含主要有机组份的废料,就需大大增加设备、劳力和能量消耗。为此采用对硝基苯甲酰氯(4),与乙醇实现酯化反应就排除了废料回收的困难,并简化后工序的操作。
Nowadays all known processes for the synthesis of benzocaine (1, p-aminobenzoate) are the starting materials, which are obtained by the inexpensive and readily available p-nitrobenzoic acid (2), esterified with ethanol and then treated with different Methods Reduction of ethyl p - nitrobenzoate (3). The main disadvantage is that a significant excess of ethanol is required for esterification at 2, difficulty in recovering ethanol, and the time for separation and refining of 3 is long and complicated. Under the conditions of production, the recovery of wastes containing major organic components requires a significant increase in equipment, labor and energy consumption. For this purpose, p-nitrobenzoyl chloride (4) is used, and the esterification reaction with ethanol eliminates the difficulty of recovery of the waste and simplifies the operation of the subsequent process.