Beckett A H, Jones G R, Hollingsbee D A
J Pharm Pharmacol. 1978 Jan;30(1):15-9. doi: 10.1111/j.2042-7158.1978.tb13146.x.
Significant losses occurred during the extraction of small quantities of ephedrine from aqueous media using either regular or analytical grades of diethyl ether. The losses were, at least in part, caused by reaction of the ephedrine with aldehydic impurities in the ether; three substituted oxazolidines were identified, using g.l.c. and g.l.c-ms. These and one other oxazolidine were synthesized and characterized by g.l.c., g.l.c.-ms, nmr and infrared spectroscopy. Alternative mechanisms for ephedrine breakdown were considered. Ephedrine was separately oxidized by three different oxidizing agents and also irradiated by ultraviolet light; the products were characterized by g.l.c., g.l.c.-ms. A method for the purification of diethyl ether is recommended to minimize ephedrine breakdown.
使用常规级或分析级二乙醚从水性介质中提取少量麻黄碱时会发生大量损失。这些损失至少部分是由麻黄碱与乙醚中的醛类杂质反应引起的；使用气相色谱法和气相色谱 - 质谱法鉴定出了三种取代恶唑烷。合成了这些恶唑烷以及另一种恶唑烷，并通过气相色谱法、气相色谱 - 质谱法、核磁共振和红外光谱对其进行了表征。考虑了麻黄碱分解的其他机制。麻黄碱分别用三种不同的氧化剂氧化并经紫外线照射；产物通过气相色谱法、气相色谱 - 质谱法进行了表征。建议采用一种纯化二乙醚的方法，以尽量减少麻黄碱的分解。
