Efficient Medium-Scale Chromatographic Group Separation of Anacardic Acids from Solvent-Extracted Cashew Nut (Anacardium occidentale) Shell Liquid

Abstract

Biologically active anacardic acids as a group have been separated from the toxic phenolic constituents (cardols and cardanols) of the solvent-extracted cashew nut shell liquid (CNSL) by a novel two-stage chromatographic method. Advantage was taken of the difference in acidity of the two groups of compounds, namely, the carboxylic acids and the phenolics, and the ability of silica gel to selectively retain amines and amine salts. CNSL (1 part) was loaded onto a silica gel bed (5 parts), prepared in a solvent system comprising ethyl acetate-hexane (25 :75) and an organic base (triethylamine, 0.5%). Continued irrigation of the bed with the same eluent resulted in the elution of all the non-acid components. The anacardic acids were subsequently eluted by changing the basic eluent to acidic by replacing the triethylamine with acetic acid (1%). This procedure was shown to be of general applicability for group separation of carboxylic acids.