Abstract

Naphthenic acids are mixtures of naturally occurring cycloaliphatic carboxylic acids recovered from petroleum distillates. The acids are present in varying amounts in crude oil and are typically recovered by caustic extraction of petroleum distillates boiling in the 200–370°C range. Commercial naphthenic acids are sold in various grades of purity. This article is a compilation of information on their composition, occurrence, manufacture, analysis, and expanding uses and was collected from a review of the literature through mid-1993. Particular attention is paid to recent analytical methods that elucidate the structure of the various components of this complex mixture. In addition to the traditional wood-treating and paint drier applications for the metal naphthenate soaps, new derivatives such as naphthenate esters and amides with uses as lubricants, surfactants, and corrosion inhibitors are also emphasized. An extensive supplementary bibliography is included for more detailed discussion of the referenced material.