Gas chromatographic separation of mercaptans as derivatives

Normal and branched mercaptans containing up to eight carbon atoms and their 2,4- and 2,5-dinitrophenylalkylthioether and thioalkylbenzoate derivatives have been analyzed by gas-liquid chromatography (GLC). The most suitable derivatives for GLC separation appeared to be the thioalkylbenzoates, which enabled all of the normal and branched mercaptans studied to be resolved on an SE-30 column. Two methods of preparation of thioalkylbenzoates with benzoyl chloride were compared: (1) derivatization with pyridine under anhydrous conditions and (2) derivatization in aqueous solution with sodium hydroxide as acceptor of hydrochloric acid. The method was faster and more effective when aqueous alkaline solution was used.