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苯妥英中间体安息香的合成,一般采用以氰化钾(钠)为催化剂的缩合反应,操作危险,三废处理困难。国内外报道用盐酸硫胺代替氰化物进行安息香缩合。但由于盐酸硫胺在碱性条件下遇热易分解,反应初期需低温操作,需要一定设备。我们选用混合碱法在常温下合成,盐酸硫胺用量减少,收率可提高为60～70%。其反应式如下:
Phenytoin intermediate benzoin synthesis, the general use of potassium cyanide (sodium) as a catalyst for condensation reaction, the operation of dangerous waste disposal difficult. Domestic and foreign reports using thiamine hydrochloride instead of cyanide benzoin condensation. However, due to heat under the alkaline conditions of thiamine decomposition, the initial reaction required low temperature operation, the need for certain equipment. We use mixed alkali synthesis at room temperature, the amount of thiamine hydrochloride reduced, the yield can be increased to 60 to 70%. The reaction is as follows: