Linalyl acetate

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). 

Bergamot. Bergamot oil is produced by cold expression from peels of fmits from the small citms tree. Citrus bergamia. The fmits are inedible and of httle value. Bergamot is grown mainly in southern Italy and northern and western Africa. The oil is used to impart a sweet freshness to perfumes. Its largest chemical constituent, to the extent of 35—40%, is linalyl acetate [115-95-7] (1), with a much smaller amount of citral [5392-40-5] (2) as an important odor contributor. 

L v ndin. Lavandin, Lavandula hjbrida as a plant species is of recent origin, unknown until the late 1920s. It is a hybrid of two common lavenders, l vandula officinalis and l vandula latifolia. Lavandin is cultivated mainly ia southern France and has become one of the most produced and used natural perfumery materials. The flowering tops of the shmb are used to produce a concrete, an absolute, and a steam-distilled oil the last is by far the most used. Low cost and refreshing odor quaUty allow lavandin to be employed ia a wide variety of perfume appHcations and at high concentrations. Chemically it is comprised of 30—32% linalool (3) and linalyl acetate (1), along with numerous other substances, mosdy terpenic. 

Uses ndReactions. Linalool can be estetified to linalyl acetate by reaction with acetic anhydride. Linalyl acetate [115-95-7] has a floral-fmity odor, reminiscent of bergamot and lavender. The price of the acetate in 1995 was 14.30/kg (45). Linalool is subject to dehydration and to isomerization to nerol and geraniol during the esterification. However, if the acetic acid formed during the esterification is removed in a distillation column, the isomerization can be minimized and good yields of the acetate obtained (130). 

The main components of Salvia mirzayanii were Linalool, Linalyl acetate, a-Tei pinyl acetate, 5-Cadinene, Spathulenol, Cubenol and a-Cadinol. The extraction yield, based on hydrodistillatin was 2.2% (v/w), and based on the SFE varied in the range of 0.65-10.59% (v/w) under different conditions. 

Determination of the enantiomeric ratio of linalol and linalyl acetate in bergamot oil... 

Mondello et al. (2, 20-23) have used a multidimensional gas chromatographic system based on the use of mechanical valves which were stable at high temperatures developed in their laboratory for the determination of the enantiomeric distribution of monoterpene hydrocarbons (/3-pinene, sabinene and limonene) and monoterpene alcohols (linalol, terpinen-4-ol and a-terpineol) of citrus oils (lemon, mandarin, lime and bergamot). Linalyl acetate was also studied in bergamot oil. The system consisted of two Shimadzu Model 17 gas chromatographs, a six-port two-position valve and a hot transfer line. The system made it possible to carry out fully... 

L. Mondello, A. Verzera, P. Previti, F. Crispo and G. Dugo, Multidimensional capillar y GC-GC for the analysis of real complex samples. Part V. Enantiomeric distribution of monoterpene hydrocarbons, monoterpene alcohols and linalyl acetate of bergamot (Citrus bergamia Risso et Poiteau) oils , 7. Agric. Food Chem. 46 4275-4282 (1998). 

The oil was found to conlain about 6 per cent, of piuene, 60 per cent-Of euoalyptol, 9 per cent, of borneol, 19 per ceul. of linalyl acetate, with a little camphor, meth. i salicylate, and sesqnitci-pene alcohol. 

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... 

Homolinalyl Acetate.—This body has the constitution CjjHjgOOCCHj, and is prepared by the action of homolinalol-sodium on acetyl chloride, or by tbe action of acetic anhydride on homolinalol. It is an oil with a marked bergamot odour, similar to that of linalyl acetate, but not identical with it. It boils at 111° to 117° at 15 mm. 

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. 

Boiling-point. Specific Gravity. Per Cent. Linalyl Acetate Indicated by Addition of 1 per Cent. 

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 —... 

Surprisingly, linalyl acetate (R = OAc) fails to undergo reduction under these conditions instead, it rapidly decomposes through cyclization and polymerization pathways.205 The same reaction conditions transform geranyl p-tolyl sulfone (R = S02C6H4Me-/ ) into a mixture of 7% reduced and 93% cyclized products within 20 hours, whereas geranyl acetate (R = OAc) gives only a 20% yield of cyclized and no reduced product (Eq. 95) 205... 

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... 

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