Analytical methods based on transformations with hydrochloric acid.
Ultraviolet spectrophotometric methods are described for alpha-ethyl benzhydrol derivatives, 3-trifluoromethyl-alpha-ethyl benzhydrol (flumecinol), 2,5-dimethyl-alpha-ethyl benzhydrol (RGH-3395) an impurity of the latter, (1,4-di-(2,5-dimethyl-phenyl)-1,4-diphenyl-butan-1,4-diol). The methods are based on dehydrations catalysed by hydrochloric acid yielding unsaturated aromatic chromophores. The determination of 2-acetyl-3-phenyl-tetrahydro-1,2,4-oxadiazin-5-one (RGH-4615) is also based on treatment with hydrochloric acid; the chromophoric compound is a benzaldoxime derivative. The hydrochloric acid-catalysed transformation of ethynodiol diacetate to its 3,5-diene derivative enables the parent compound to be determined by gas chromatography.