SESQUITERPENES IN THE PERFUMERY INDUSTRY 223 Distilled oil Crude Cedarwood oil Distillation Grades of Cedrene (Hydrocarbon mixtures) / • epoxy cedrane Epoxidation A••. acetyl cedrane ( Ci7H260 ketones) Distilled cedrol • Cedrol crystals fication Cedryl acetate Cedrenol Esterification (alcohol cut' • cedrol and % Cendrenyl acetate other alcohols Figure 31. Perfumery materials from cedarwood oil (93). Acetic Anhydride Catalyst Figure 32. some 605/o of the reaction product. The major ketone is thought to be the active odour constituent of acetyl cedrene. It is said to have a powerful woody, musk-ambergris odour far greater in intensity than any of the other isomers. This acetyl thujopsene isomer has an interesting odour-structure relationship since, although it has a strong musk odour, it has no aromatic ring as have most other tricyclic musks possessing an acetyl group. Patchouli oil has wide application in the perfumery industry and more extensive use would be made of this essential oil if it were in greater supply. Much effort has been devoted to the analysis of the oil and a number of constituents have been identified. No single compound has the total patchouli odour and any effort to formulate a reconstructed patchouli oil will require the synthesis of a number of sesquiterpene alcohols, ketones and hydrocarbons. The main alcohol constituent of patchouli oil is patchouli alcohol. A synthesis of this alcohol from homocamphor has been reported (101) but

224 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Figure 33. Products of acid isomerization of thujopsene (95). 52% Acetylof ion + 5other i$omers Fieure 34. The acetylation of thujopsene (96, 97). 9%