Synthesis of diesters as diesel fuel marker from palm oil

Abstract

Five diester compounds were synthesized by reaction of carboxylic acids and five alcohols which were methanol, ethanol, isopropanol, butanol, 2-ethyl-1-hexanol in sulfuric acid. Carboxylic acids were synthesized by ozonolysis of palm oil, followed by oxidation with mixture of hydrogen peroxide and formic acid. These ester compounds were obtained in good yield (>75%). Ester compounds were purified by silica gel column chromatography, characterized by GC-MS, FT-IR, 1H-NMR and 13C-NMR. The mixture of ester compounds can be used as marker in diesel fuel at concentration of about 400-500 ppm. Detection method was developed for field test by the reaction with hydroxylamine and ferric chloride. Violet color was found. Gas chromatographic analysis indicated unique profile of each mixed ester. However, quantitative analysis by GC was obscured by diesel base oil even at concentration of ester as high as 10,000 ppm.