在冰醋酸溶液中L(+)-伪麻黄碱的异构化

在冰醋酸溶液中,L(+)-伪麻黄碱可以异构化成D(-)-麻黄碱。氧化铝薄层层析结果表明:在反应液中存在N-乙酰L(+)-伪麻黄碱,N-乙酰D(-)-麻黄碱和一种未鉴定结构的化合物,并初步推出可能的异构化机理。5-10％L(+)-伪麻黄碱的冰醋酸溶液,回流反应20小时,立即回收醋酸后,用2.5/V的氢氧化钠溶液进行水解,再通过草酸盐变为盐酸盐即得。以L(+)-伪麻黄碱计纯盐酸D(-)-麻黄碱收率达31.2％。

A STUDY ON ISOMERIZATION OF L(+)-ψ-EPHEDRINE IN GLACIAL ACETIC ACID

L(+)-ψ-ephedrine could be isomerized to D(-)-ephedrine in glacial acetic acid. The method of isomerization was rather easy as follows:A 5% solution of L(+)-ψ-ephedrine in glacial acetic acid was refluxed for twenty hours, then acetic acid was removed immediately from the mixture under diminished pressure. The residue was hydrolyzed with 2.5 N NaOHsolution. The D(-)-ephedrine oxalate was first prepared from the product of hydrolyzation and finally converted to its hydroehloride. The yield of pure product was about 31.2% of the theoretical based on the L(+)--ephedrine.