Yang S K
Department of Pharmacology, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD 20814-4799, USA.
J Pharm Pharmacol. 1995 May;47(5):442-6. doi: 10.1111/j.2042-7158.1995.tb05826.x.
Chlordiazepoxide (a 1,4-benzodiazepine 4-oxide) is an anxiolytic/hypnotic drug in clinical use. It was reported to be predominantly protonated at the N-oxide oxygen in acidic aqueous solutions at pH << 4.6 (pKa). We have studied the acid-base equilibria of three 1,4-benzodiazepine 4-oxides (chlordiazepoxide, diazepam 4-oxide, and nordiazepam 4-oxide) by ultraviolet-visible spectrophotometry. The results indicate that chlordiazepoxide is not protonated at the N-oxide oxygen, but rather at the nitrogen of an imine bond between C2 carbon and its nitrogen substituent in acidic media.
氯氮䓬（一种1,4-苯二氮䓬4-氧化物）是一种临床使用的抗焦虑/催眠药物。据报道，在pH远低于4.6（pKa）的酸性水溶液中，它主要在N-氧化物氧处质子化。我们通过紫外可见分光光度法研究了三种1,4-苯二氮䓬4-氧化物（氯氮䓬、地西泮4-氧化物和去甲地西泮4-氧化物）的酸碱平衡。结果表明，氯氮䓬在酸性介质中不是在N-氧化物氧处质子化，而是在C2碳与其氮取代基之间的亚胺键的氮处质子化。
