Linalyl esters

Linalool, 3 231, 232, 233 24 477, 495, 496, 500-503, 546 acid treatment of, 24 502 epoxidation of, 24 502 main producers of, 24 501 Linalool oxide, 24 502 Linalyl, 24 479 Linalyl acetate, 24 501 Linalyl alcohol, 24 500 Linalyl esters, 3 231 Linalyl oxide, 24 503 Lincomycin, registered for use in aquaculture in Japan, 3 221t Lincosamide, bacterial resistance mechanisms, 3 32t Lindane, 13 145-147... 

Uses. Linalool is used frequently in perfumery for fruity notes and for many flowery fragrance compositions (lily of the valley, lavender, and neroli). Because of its relatively high volatility, it imparts naturalness to top notes. Since linalool is stable in alkali, it can be used in soaps and detergents. Linalyl esters can be prepared from linalool. Most of the manufactured linalool is used in the production of vitamin E. 

Among the linalyl esters, the acetate is by far the most important fragrance and flavor substance. The formate, propionate, and butyrates are used in small amounts. 

Occurrence (- )-L. in Brazilian rosewood oil (Brazilian linaloe oil , Anita rosaeodora, Lauraceae) 80-85% (+)-L. (coriandrol) in coriander oil (60- 80%) and in Mexican linaloe oil Bursera del-pechiana=B. penicillata, Burseraceae) 60-65%. L. also occurs bound to various carboxylic acids, e.g., linalyl acetate (3-acetoxy-3,7-dimethylocta-1,6-diene, C,2H2o02, Mr 196.29). The linalyl esters are synthesized from L. since they have various plications in perfumery. For synthesis of L., see Lir.. L. and L. esters are used in the perfume industry and for the synthesis of tocopherols. 

Anthranilic acid, 1,5-dimethyl-1-vinyl-4-hexenyl ester Anthranilic acid linalyl ester. See Linalyl anthranilate... 

Cinnamic acid, linalyl ester. See Linalyl cinnamate... 

Synonyms Anthranilic acid, 1,5-dimethyl-l-vinyl-4-hexenyl ester Anthranilic acid linalyl ester 3,7-Dimethyl-1,6-octadien-3-ol 2-ami nobenzoate 3,7-Dimethyl-1,6-octadien-3-yl anthranilate 1,5-Dimethyl-1-vinyl-4-hexen-1-yl-o-aminobenzoate... 

The principal difference between English and French oil of lavenda is that the former contains only a very small quantity of linalyl esters whilst cineol appears to be a normal constituent of English oil. Semmler and Tiemann have isolated from English oil the terpene limonene, linalol, and i-linalyl acetate. Cineol and a sesquiterpene are also normal constituents of the oil. 

Aroma chemicals are isolates, or chemically treated oils or components of oils. Some components are removed physically, others chemically. In most cases, they are further purified by distillation. For example, Bois de Rose (rosewood) oil may be distilled to isolate linalool, which may be then further treated chemically to yield derivatives such as linalyl acetate, an important fragrance ingredient and a primary component in its own right of lavender and lavandin oils. Vetiver oil Haiti, although containing only 70% alcohols, is treated with acetic anhydride, then carefully distilled to include valuable odor components in the distillate, even though they may not be esters. 

Generally speaking, lavandin oil is characterized by a lower quantity of esters, the most critical of which for odor quaUty is linalyl acetate (24). The French specification organization (AFNOR) has fixed provisional standards for both oils (17) (Table 6). 

Linalool can be converted to geranyl acetone (63) by the CarroU reaction (34). By transesterification with ethyl acetoacetate, the intermediate ester thermally rearranges with loss of carbon dioxide. Linalool can also be converted to geranyl acetone by reaction with methyl isopropenyl ether. The linalyl isopropenyl ether rearranges to give the geranyl acetone. 

The acetates of most alcohols are also commercially available and have diverse uses. Because of their high solvent power, ethyl, isopropyl, butyl, isobutyl, amyl, and isoamyl acetates are used in ceUulose nitrate and other lacquer-type coatings (see Cellulose, esters). Butyl and hexyl acetates are exceUent solvents for polyurethane coating systems (see Coatings Urethane polymers). Ethyl, isobutyl, amyl, and isoamyl acetates are frequentiy used as components in flavoring (see Flavors and spices), and isopropyl, benzyl, octyl, geranyl, linalyl, and methyl acetates are important additives in perfumes (qv). 

The fact that the amount of total linalol decreases whilst the richness in linalyl acetate increases, proves that linalol appears in the plant at an earlier period than its acetic ester. Further, the free acetic acid acting on the linalol esterifies a portion of it, whilst another portion of this terpene alcohol is dehydrated, with the production of limonene and. dipentene, which are the usual resultants of linalol in presence of certain dehydrating agents. This view is corroborated by the fact that the quantity of the mixed terpenes increases during the esterification, without the slightest variation being observed in the ratio between the... 

Linalyl Formate.—The formic acid ester of linalol, CjqHj OOCHj, has a distinctive odour somewhat resembling that of the acetate. It is an oil boiling at 189° to 192°, and is prepared by treating linalol with formic acid, but the reaction is not complete and commercial samples are never pure esters. 

Linalyl Propionate.—This ester is also produced by condensing the free alcohol and the free acid by means of sulphuric acid. It has a somewhat fruity odour recalling that of bergamot, and is especially suitable for perfumes of the lily of the valley type. It is a colourless oil, boiling at 115° at 10 mm. pressure. 

Linalyl Butyrate.—The butyric ester of linalol has the formula, CiflHjjOOC, CH2. CHjCHj. It resembles geranyl butyrate in odour, but is somewhat heavier. It is most useful for imparting fruity odours to flower perfumes. It is prepared by condensing the alcohol and the acid by means of sulphuric acid. 

Esters, or salts of alkyl radicles, such as linalyl acetate, etc., are frequently the most important constituents of essential oils. Their importance is especially noteworthy in such cases as lavender , bergamot, peppermint, and wintergreen oils, and their estimation is very frequently necessary. The principle upon which this depends is the fact that most esters are decomposed by solution of caustic alkali (preferably in alcohol) according to the equation—... 

As the free acids present in essential oils consist in the main of acetic acid, they are, when necessary, calculated in terms of acetic acid in the same way the esters are conventionally calculated from the alkali required for their hydrolysis, in terms of the principal ester present, for example, linalyl acetate in the case of lavender and bergamot oUs, and geranyl tiglate in the case of geranium oil. 

Terpinyl acetate in the absence of esters of high molecular weight, or ethyl esters of the fatty acids of coconut oil, is indicated by a difference to be observed in the apparent ester value by different times of saponification. This ester is far more resistant to the action of caustic alkali than is linalyl acetate, and requires two hours at least for complete saponification. Hence, if the oil shows a difference in the saponification value in thirty minutes and in two hours, which amounts to more than from 1 to 2, terpinyl acetate is almost certainly present. The following table shows the effect of this partial-saponrfication on the two esters and on adulterated oils —... 

A considerable portion of commercially available geraniol is produced by a modified process linalool obtained in a purity of ca. 65% from a-pinene is converted into linalyl borates, which rearrange in the presence of vanadates as catalysts to give geranyl and neryl borates. The alcohols are obtained by hydrolysis of the esters [32]. 

Because the lower fatty acid esters of geraniol, linalool, and citronellol are important contributors to the odor of many essential oils, these esters are widely used in the reconstitution of such oils, as well as in perfume and flavor compositions. The acetates, particularly linalyl acetate, are most widely used. The use of formates is limited by their relative instability. Higher esters are not important in terms of quantity, but are indispensable for creating specific nuances. 

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