HESP—A New Essential Oil From the Acid Hydrolysate of Spent Sandal Heartwood

In India, Santalum album L. is mainly exploited for its scented heartwood and the fragrant essential oil obtained from it. Sandalwood oil, which is the most important Indian essential oil of extensive perfumery use, is obtained from the heartwood in 2.5-6.5% yield depending on the age of the wood and, its color. Previous studies have shown that the oil was found to contain 90% α- and β-santalol, 6% hydrocarbons (α-santalene, β-santalene and epi-β-santalene), aldehydes (tricycloekasantalal, exo-norbicycloekasantalal and teresantalal), ketones, phenols, acids and heterocyclic compounds.

In the present study, the utilization of the spent (exhausted) sandalwood powder from steam distillation as a source of an acid hydrolysate oil is examined. It has been found that hydrolysis of the non-volatile portion of an acetone extract of the spent sandalwood powder with methanolic hydrochloric acid followed by steam distillation gave rise to a new essential oil (1.2% yield) which we have called HESP, the acronym for hydrolyzed exhausted sandalwood powder.


Five hundred grams of sandal heartwood powder was distilled for 18 hours and 3.5% of sandalwood oil was obtained. The spent powder from distillation was air-dried and then, once dry, was soxhlet extracted (hot) with 1 liter of acetone for 6 hours. After removal of the acetone, the extract was distilled for 10 hours to remove any traces of sandalwood oil. Next the residual extract was extracted with ethyl acetate and then the solvent was stripped from the soluble portion to leave a dark-red viscous liquid of non-volatile material in 4.5% yield. To 10 g of this red viscous extract, 20 ml of methanol and 10 ml of concentrated hydrochloric acid was added and the mixture was refluxed for 3 hours. Finally, after evaporation of the solvent, the residue was steam distilled for 18 hours and the strongly scented HESP oil was obtained in 1.2% yield on diethyl ether extraction of the distillate. It was found that on silica gel chromatography, the acetone extract of the spent heartwood powder gave a sandal note possessing fraction in the benzene elute and a purely non sandal note fraction; the latter, upon acid hydrolysis, gave HESP oil in a somewhat lower yield.

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