Лако-красочные материалы — производство

Two main families of cedarwood oils are used in perfumery. The first is extracted from trees of the family Juniperus. These oils are known as English, Texan or Chinese cedarwood and their components are derived from the cedrane and thujopsane groups of sesquiterpenes. Atlas and Himalayan cedarwoods are obtained from Cedrus species and their terpenes are mostly from the bisabolane family. The cedrane — thujopsane derivatives are much more widely used than the bisabo — lanes.

The major components of the Juniperus wood oils are cedrol, cedrene and thujopsane, and a number of perfume ingredients are made from

these. The most important is acetylated cedarwood, which possesses a much stronger cedarwood odour than the natural oil; it is available under various tradenames such as Lixetone® and Vertofix®. The acetylation can be carried out using acetyl chloride in the presence of a Lewis acid or by using a Bronsted acid system such as polyphosphoric acid-acetic anhydride or sulfuric acid and acetic anhydride. The cedrol may be removed before acetylation or allowed to dehydrate to give cedrene under the reaction conditions and so the major component in the product is acetylcedrene. However, the main contributor to the odour of the complex reaction product mixture is the ketone derived from acetylation of thujopsene (Daeniker et al., 1972), These reactions are shown in Scheme 4.31.

Scheme 4.31

Sesquiterpene chemistry is always full of surprises. For example, an attempt to use titanic chloride in place of aluminium chloride to produce acetylcedrene resulted in a previously unknown compound (McAndrew et al., 1983). In this case, as shown in Scheme 4.32, the carbocation produced by addition of the acetyl cation to cedrene, instead of eliminating a proton as normal, underwent a Wagner-

Meerwein rearrangement to a second cation, which was then trapped by trans-annular addition of the carbonyl group.

The methyl ether of cedrol is also used as a woody-amber note. The Atlas and Himalayan cedarwoods have a sweeter and less ambery woody smell than the materials described above. This odour is due to materials such as atlantone (25) and deodarone (26).