INTERFACIALLY ACTIVE ACIDS IN A CALIFORNIA CRUDE OIL . ISOLATION OF CARBOXYLIC ACIDS AND PHENOLS

This report is part of a general study of the naturally occurring anionic surfactants in a Midway Sunset (California) crude oil. Quantitative extraction was effected with alcoholic base. The crude oil contains 2.5 wt% carboxylic acids which, in the presence of aqueous alkali, are interfacially active. The acids were separated from phenols by a sequence of exhaustive back extractions with petroleum ether, two-stage ion exchange, and repeated silica gel chromatography. Pure phenolic material is interfacially inactive. Car-boxyphenols appear to be present. During isolation, about one third of the interfacially active acids was generated from the original crude oil by hydrolysis. Spectroscopic and chemical evidence is given for the presence of phenols and carboxylic acids. Number average molecular weights determined on the methyl esters and acids by three different methods indicate a range of 300-400. A quantitative infrared technique for acid value determination is described. Hetero-atoms appear to be incorporated in some of the active acids. © 1969, American Chemical Society. All rights reserved.