Citronellol acetate

Dimethyl-6-octen-1-ol, acetate Citronellol acetate C12H22O2 160-84-6 198.302 1161" ... 

Chlorobenzyl chloride 1950 2-Chloro-/>-phenylenediamine 1876 Citronellol acetate 4199... 

There seems, however, to-day, to be overwhelming evidence that the French chemists were correct and that citronellol and rhodinol are two very similar, but chemically different, compounds, citronellol being represented by the formula (1) and rhodinol by formula (2). Considerable evidence of this is to be found in the work of Barbier and Locquin. Starting from the acetic esters of ordinary d-citronellol and rhodinol from oil of geranium or rose, they attached hydrogen chloride to the double bond, and obtained the same additive product according to the equations — ... 

Further evidence of the difference between rhodinol and citronellol is forthcoming, in that the former yields on oxidation an aldehyde, rhodinal, whose oxime does not yield citronellic acid nitrile when treated with acetic anhydride, nor citronellic acid when the nitrile is treated with alkalis, wheras citronellal, the aldehyde of citronellol, does yield the nitrile and citronellic acid. 

Citronellyl Acetate.—The odour of the acetic ester of citronellol recalls to some extent that of hergamot. It is a natural constituent of geranium oil, and is useful in small amounts for blending with rose and geranium odours. It is prepared hy the action of acetic anhydride on citronellol. When pure it has the following characters —... 

The unusual system franx-RulOl lTMPl/N OllO atm)/fluorobenzene epoxidised linear alkenes, cholesteryl acetate and the ferf-butyldimethylsilyl ether of citronellol [592] cholest-5-ene-3-one was oxidised to the 6a and 6p alcohols and the enedione by franx-RulOl lTMPl/OXCgH (Table 3.2) [593]. With ter-penes the 6,7-double bonds were selectively epoxidised by fran -Ru(0)2(TMP)/... 

However, the lower fatty acid esters (particularly the acetates) of the acyclic terpene alcohols geraniol, linalool, and citronellol are extremely important both as fragrance and as flavor substances. The acetates occur in many essential oils, sometimes in rather high amounts. Formates, propionates, and butyrates occur less frequently. As a result of the development of large-scale production processes for terpenes, the esters of acyclic terpene alcohols are nearly always made synthetically. All acyclic terpene esters that are used as fragrance and flavor materials can be prepared by direct esterification of the appropriate alcohols. However, special precautions are required for the esterification of linalool. 

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. 

The most important and frequently used terpene esters in flavours are the acetates of nerol, geraniol, citronellol, linalool and isoborneol [12], As discussed before, all these terpene alcohols are available both from renewable resources and from petrochemical origin. Acetic acid can be obtained from renewable resources by pyrolysis of wood as wood vinegar, and also by synthesis from petrochemical origin. 

The biotechnological production of flavour compounds is particularly focused on esters and lactones. Lipase from Mucor miehei is the most widely studied fungal lipase [30-35]. Esters of acids from acetic acid to hexanoic acid and alcohols from methanol to hexanol, geraniol and citronellol have been synthesised using lipases from Mucor miehei, Aspergillus sp., Candida rugosa, Rhizopus arrhizus and Trichosporum fermentans [32-37]. 

Uses and Reactions. The main use for citronellol is for use in soaps, deteigents, and other household products. It is also important as an intermediate in the synthesis of other important fragrance compounds, such as citronellyl acetate and other esters, citronellal, hydroxycitronellal, and menthol. 

Citronellol is easily esterified with acid anhydrides or carboxylic acids, catalyzed by mineral acids. The price of citronellyl acetate [150-84-5] in 1995 was 10.45/kg (45). Other esters such as the formate and isobutyrate are also used. 

R,S)-Citronellal can be purchased from BASF, and (R)-citronellal from Dragoco, Fluka, or Takasgo Perfumery Co., Ltd., Japan. (R)-Citronellal can also be synthesized from pulegone with ee >99%.5 (S)-Citronellal may be obtained by oxidation of (S)-citronellol,6 which is accessible by different routes with ee 95%.7 The optical purity of citronellal can be determined by GLC after conversion to the acetal of (-)-(2R,4R)-pentanediol.8 For the reactions described, (R,S)-citronellal from BASF, (R)-citronellal from Dragoco, and (S)-citronellol from Fluka were used. (R,S)-Citronellal... 

Many essential oils contain esters (mostly acetates) of alcohols of the formulae C10HlsO (borneol, geraniol, terpineol, linalool), C H O (menthol, citronellol), C1SH240 (santalol). When boiled with alcoholic potash, these esters are hydrolysed (saponified) and yield the free alcohol and the potassium salt corresponding with the acid of the ester. Thus, the volatile oils containing esters have saponification numbers, which may be determined in a manner analogous to that used for fatty matters. 

Free Alcohols alone.—In this case the content in free alcohols (borneol, geraniol, terpineol, linalool, menthol, citronellol, santalol, thujyl alcohol) is determined by transforming the alcohols into the corresponding acetates by boiling with acetic anhydride and then determining the saponification number of the acetylated product acetyl saponification number). 

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