Sesquiterpenoids patchouli alcohol

The sesquiterpenoids that are important in odour terms mostly have complex cyclic structures. The problem of elimination of alcohols to produce olefins on attempted isolation is even more acute with sesquiterpenoids than with monoterpenoids because of their higher boiling points, which require more vigorous distillation conditions. The sesquiterpenoids responsible for the odours of vetiver and patchouli oils have complex structures which can only be reached by lengthy and hence uneconomic syntheses. Some of these components are shown in Figure 4.33. The vetivones are the major components of vetiver oil but contribute little to the odour. Minor components such as zizanal and khusimone are much more important. Similarly in patchouli oil, minor components such as nor-patchoulenol and nor-tetrapatchoulol are more important than the major constituent, patchouli alcohol. 

Phytochemistry Needles and young branches contain vitamin C, essential oil (with up to 40 components such as camphene, myrcene, bomyl acetate, and others), flavonoids, and microelements (iron, manganese, chromium, aluminium and copper Bykov 1950). Thirty-eight diterpenoids have been identified in the oleoresin (Raldugin et al. 1991). Sesquiterpenoids, diterpenoids, triterpenoids, steroids, and tocopherol were isolated from needles and twigs. Dehydroabietol, patchouli alcohol, guaiol, P-sitosterol, and campesterol were the main components of the unsaponifiable matter (Zhou 2001). 

Vetiver and patchouli are two oils of great importance in perfumery (Williams, 1996, 2004). Both contain complex mixtures of sesquiterpenoids, mostly with complex polycyclic structures (Sell, 2003). The major components of vetiver oil are a-vetivone (136), b-vetivone (137), and khusi-mol (119), but the most important components as far as odor is concerned are minor constituents such as khusimone (151), zizanal (152), and methyl zizanoate (153). Nootkatone (154) is an isomer of a-vetivone and is an important odor component of grapefruit. Patchouli alcohol (145) is the... 

Patchouli oil is distilled from the fermented leaves of Pogostemon cablin. Its main constituent is patchouli alcohol [5986-55-0] (257), also known as patchoulol. However, this and the other major components have relatively little odor and the characteristic scent arises from some of the minor compounds present. Vetiver oil is distilled from the roots of the tropical grass Vetivera zizanoides. It contains a very large number of sesquiterpenoids, a-vetivone (258), (3-vetivone (259), and khusimol (260) accounting for 35% but, as with patchouli, it is a number of minor components that are responsible for its valuable odor. Details of patchouli and vetiver chemistry can be found in Chapter 7 of the book by Sell (323). 

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