Sandalwood materials

Camouflaged boranes, 4 190-191 Campanulales, alkaloids in, 2 75 Camphene, 3 231 24 477, 478, 497-498 Campholenic aldehyde, 24 496, 534—536 sandalwood materials made from, 24 535-536... 

Sandalwood oil is obtained by distillation of the parasitic tree Santa-lum album. The major components of the oil are the santalols (27, 28). Many syntheses of these and related chemicals have been reported but, elegant as they are, none compete economically with the oil itself. The synthetic sandalwood materials fall into two main classes, the so-called terpenophenols and the materials derived from campholenic aldehyde. 

The members of the second family of synthetic sandalwood materials are derived from campholenic aldehyde (6.72). This aldehyde is prepared by treatment of a-pinene oxide (6.71) with a Lewis acid, usually zinc chloride or bromide. a-Pinene oxide is, in turn, prepared from a-pinene... 

Figure 6.18 shows the general scheme for the preparation of sandalwood materials from campholenic aldehyde (6.72) and also three typical members of the family. 

Aldol condensation between campholenic aldehyde (6.72) and an aldehyde or a ketone (6.73) produces an unsaturated derivative (6.74). It should be noted that this material contains an -double bond. The reason for this lies in the mechanism of the aldol condensation as described in Figure 6.4 and associated text. The carbonyl group of (6.74) can be reduced to the corresponding alcohol by, for example, a complex metal hydride such as lithium aluminium hydride or sodium boro-hydride. This produces the sandalwood material (6.75). Three typical examples are shown at the bottom of Figure 6.18. The first, (6.76), is known under various trade names such as Bangalol (Quest) and is... 

An important use of camphene is for the production of synthetic sandalwood materials. When camphene reacts with guaiacol (2-methoxyphenol) in the presence of a Brpnsted or Lewis acid, a mixture of terpenylphenols is formed. Hydrogenafitm of the mixture results in hydrogenolysis of the methoxy group and gives a complex mixture of 130 terpenylcyclo-hexanols, such as 3-(2-isocamphyl)cyclohexanol [3407 2-9] for unspecified absolute... 

FIGURE 8.49. Sandalwood materials made from campholenic aldehyde. 

Campholenic aldehyde is not used per se in perfumery, but is of importance as the precursor for a range of sandalwood materials. This is of increasing importance as the supply of natural sandalwood is insufficient to meet demand and overharvesting has put the future of the species (Santalum album) at risk. 

OC-Santalol. Sandalwood oil is comprised of mainly (90%) a- and P-santalol, which gives the oil the woody, tenacious sandalwood odor. An impure a-santalol [115-71 -9] (100) can be isolated by the distillation of the oil. P-Santalol [77-42-9] (101) is also isolated but ia much smaller amounts. The price of sandalwood oil, E. Indian, ia 1995 was 286/kg, and the oil from Indonesia was 187/kg (69). The high price of these oils has created the need to synthesize new materials with the sandalwood odor. The terpenophenols are manufactured by condensation of camphene with phenoHc compounds followed by hydrogenation to the cycloaUphatic alcohols (194). 

Another opportunity to combine two reaction steps towards a one pot synthesis is the epoxidation of a-pinene and the isomerization of the epoxide to campho-lenic aldehyde (Scheme 5.6). Zeolite Ti-Beta seems adequate to deal with both steps as a catalyst [24]. Campholenic aldehyde is the starting material for several sandalwood fragrances. 

Some alicyclic alcohols are important as synthetic sandalwood fragrances. A few alicyclic aldehydes are valuable perfume materials and are obtained by Diels Alder reactions using terpenes and acrolein. Esters derived from hydrogenated aromatic compounds, such as /cr/-butylcyclohexyl and decahydro-/3-naphthyl acetates, are also used in large amounts as fragrance materials. 

The product can be used to replace traditional materials such as sandalwood, vetivert and patchouli in perfume compositions. 

Sesquiterpenic alcohols used in perfumery are mainly of natural origin. Three alcohols of this type are shown in Figure 8. Cedrol is the main alcohol constituent of cedarwood oil. Alpha-santalol constitutes about 80% of sandalwood oil and about 30% patchouli alcohol is found in patchouli oil, a very popular woody-earthy fragrance material. 

Some of the chemistry developed by the industry more recently, to produce new monohydric alcohols, is just as interesting as the linalool chemistry. Sandalore, a recent new Givaudan chemical with a persistent, sandalwood odor is made according to the scheme in Figure 15 (9). Alpha-pinene, the starting material, is converted to the epoxide which is catalytically rearranged to campholen-ic aldehyde. Aldol condensation with methyl ethyl ketone followed by hydrogenation yields Sandalore . 

This overview of monohydric alcohols covered the major products used by the industry. The one exception was Sandalore which was introduced only recently. It was included as an example of the continuing search for new fragrance materials to replace natural products,in this case, expensive and scarce sandalwood oil. 

The base note also contains the important accord between methyl ionone (10%), vetiveryl acetate, sandalwood, musk ketone, and originally musk ambrette. These materials together with the carnation make up the immediately recognizable central character of the perfume. 

The woody part of the perfume is again based on vetiveryl acetate with vetiver (6%) and sandalwood. The oakmoss is backed up by a small amount of Evemyl, a synthetic material created as a result of the study of natural oakmoss, and one that has come to play an increasingly important role in modern perfumery. Coumarin is again present with a trace of vanillin, and cyclopentadecanolide backs up the musk ketone. 

Otherwise, in general construction the perfume follows closely that of a classical oriental, with citrus oils (making up some 25%), lavender, sandalwood, patchouli, vanillin, coumarin, castoreum, and rose. The general sweetness of the perfume is further enhanced by the choice of musk materials, Galaxolide (5%), Tonalid, ethylene brassylate, and musk ketone, as well as by the use of Cashmeran, an intensely sweet fruity musk material associated with the synthesis of Galaxolide. 

Although we have described the perfumes in this family as being based on Hedione, in Coriandre the material used is Magnolione, a closely related material with a very similar though rather more jasminic olfactory character. This makes up some 20% of the formula with 10% of patchouli. Methyl ionone, vetiveryl acetate, cedryl acetate, Vertofix, and sandalwood make up the woody aspect of the fragrance, with a small amount of Galaxolide as the musk. 

Apart from the materials already mentioned the top note contains a simple mixture of bergamot and orange. The middle note is dominated by a traditional jasmin base, with muguet (hydroxycitronellal 10%), and rose. At the heart of the perfume is the classical chypre accord between vetiveryl acetate (10%), methyl ionone, oakmoss, aldehyde C14, coumarin, sandalwood, patchouli, musk ketone, and amber. The amber note can be reproduced by the simple but effective combination of labdanum, olibanum, and vanilla. Small amounts of other animalic notes such as civet may also be used. 

The dominant woody aspect of the perfume is made up of Vertofix (12%), vetiver notes, cedryl acetate, and sandalwood, with guaiacwood supporting the rose. The mossy character comes from oakmoss and a complex based on isobutyl quinoline reminiscent of Mousse de Saxe. There is also a small amount of a spicy carnation note including one of the sweet spices such as clove or pimento. The wonderful richness of the perfume suggests the addition of numerous other materials in very small amounts, and it is probable that in the creation of a perfume such as this tinctures of musk, ambergris, and civet would also have been used. 

Box 7.19 Material safety data sheet for Sandalwood (Santalum album)... 

Since the dawn of civilization, say, 5000 years ago perfumes and perfumery chemicals encompassing flavors and fragrances and even pleasant food additives attracted attention in India and were used in temples, religious rites and even for personal sophistication. The earliest reference to such materials was to he found in the Vedas, say, during 2000-2500 BC. In particular, sandalwood, camphor, saffron, etc. were mentioned in connection with certain rites. 

NATURAL products Plants that can provide odiferous materials, e.g. rose, sandalwood, grapefruit, etc. 

This stereoselectivity was also useful for synthesis of material reputed to possess sandalwood-like odors [equation (g)] , and for the preparation of the axial alcohol frans-9,10,c/s-8,9-f/-8-hy oxy-2-methyldecahydroisoquinoline °. 

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