ANALYSIS OF CRUDE OIL CARBOXYLIC ACIDS AFTER CONVERSION TO THEIR CORRESPONDING HYDROCARBONS

A new and comprehensive approach has been developed for the identification of carboxylic acids in virgin crude oil. Knowledge of the structures of these acids is relevant to questions concerning the origin of petroleum and the origin of life. The identification involves initial conversion of acids, via the corresponding alcohols and their p-toluene sulfonate esters, to hydrocarbons. The hydrocarbons are separated by a combination of silica gel and gel permeation chromatography and identified by ultraviolet, infrared, and high resolution mass spectrometry. For the acid-hydrocarbon conversion, proof was obtained for the maintenance, on an average statistical basis, of most of the carbon skeletal structures of the original acids. The structure determination of the hydrocarbons and the retention of carbon skeleton during conversion permits identification of many classes of carboxylic acids not previously discovered in virgin crude oil. These classes include polycyclic naphthenic, mono-, di-, and polynuclear aromatic, mono- and dibenzthiophenic, carbazolic, and phenolic types. This identification procedure affords the first semiquantitative assessment of carboxylic acid classes in a crude oil relative to all of the acids present. © 1969, American Chemical Society. All rights reserved.