Menthol fragrance chemical

Uses ndReactions. The largest use of myrcene is for the production of the terpene alcohols nerol, geraniol, and linalool. The nerol and geraniol are further used as intermediates for the production of other large-volume flavor and fragrance chemicals such as citroneUol, dimethyloctanol, citroneUal, hydroxycitroneUal, racemic menthol, citral, and the ionones and methylionones. 

This isomerization is enantioselective when optically active BINAP is used and provides practical access to optically active aldehydes and alcohols such as L-menthol, which is a key fragrance chemical [297—299], The proposed mechanism involves amine, iminium, and enamine as complex intermediates [300], Extension of this olefin isomerization is realized in the isomerization of an alkyne to a conjugated diene (Scheme 1-47) [301], High chemoselectivity is achieved when Pd(OAc)2 or [Pd2(dba)3]/HOAc, in the presence of phosphine, is used as catalyst (Table 1-14). The phosphine of choice is dppb although dppf could give a similar yield. 

Some of the esters and ethers of 79-cresol and its derivatives have become very popular in the manufacture of synthetic perfumes. Prominent among them are 79-cresyl methyl ether, p-cresyl acetate, p-cresyl phenyl acetate, etc. Some of them are very popular in the manufacture of Indian agarbattis (incense sticks). Thymol and menthol which were traditionally obtained from the natural sources are now synthetically made from m-cresol and are much cheaper as flavor and fragrance chemical than the natural ones. BAYER AG of Germany is the largest manufacturer of synthetic thymol and menthol. 

Besides the more common reactions such as hydrogenation, isomerization, alkylation, and the Diels-Alder reaction. Sharpless epoxidation and dihydroxylation by asymmetrical catalysis are rapidly emerging as reactions with immense industrial potential. Table 9.7 lists some important syntheses based on asymmetric catalysis. These include processes for the pharmaceutical drugs (S)-naproxen, (S)-ibuprofen, (,S)-propranolol, L-dopa, and cilastatin, a fragrance chemical, L-menthol, and an insecticide (/ )-disparlure. Deltamethrin, an insecticide, is another very good example of industrial asymmetric synthesis. The total synthetic scheme is also given for each product. In general, the asymmetric step is the key step in the total synthesis, but this is not always so, as in the production of ibuprofen. Many of the processes listed in the table are in industrial production. 

The main industrial application of P-pinene is the noncatalytic thermal isomerization reaction in the vapor phase to yield P-myrcene (besides limonene and p-menthadiene) as an intermediate for the commercial production of flavor and fragrance chemicals (Figure 3B.6), such as the terpenic alcohols geraniol, nerol and linalool, and synthetic aromas (citral, citronellal, menthol, and myrcenol). ... 

Enantiomerically pure citronellal in both of its antipodal forms has outstanding importance as a key intermediate for the production of fine chemicals, especially for the production of fragrances and flavors. In this respect the isomerization of diethylgeranylamine to R) -citronellal enamine in the presence of Rh /(S) -BINAP is an exceptional industrial process, for instance as one of the key steps of the Takasago process for the production of (-) -menthol [22]. In the search for alternatives for this process, both Josiphos and Daniphos derivatives were evaluated (Scheme 1.4.5) [23]. 

Aroma chemicals which are found in natural sources or food preparations but are synthesised by normal chemical procedures are defined by the status nature-identical . Most of them were discovered and developed during the nineteenth and twentieth centuries. The most important single aroma chemicals produced in very large amounts are vanillin, menthol, citral and anethol. They are used not only by flavour producers but also in large amounts in fragrance... 

Alcohols occur widely in nature. Methanol is also known as wood alcohol because it can be obtained by distilling wood in the absence of air. It is very poisonous and can cause blindness or death if ingested. Ethanol is consumed in alcoholic beverages. Other simple alcohols, such as 2-phenylethanol from roses and menthol from peppermint, are constituents of natural flavors and fragrances. Alcohols are important intermediates in chemical synthesis. They are also commonly used as solvents for various chemical processes. Ethylene glycol is used in antifreeze and in the preparation of polymers such as Dacron. 

There are more than 150 natural essential oils and natural extracts from which a large number of important flne chemicals in the field of flavor and fragrances have been extracted, isolated, and sold as blends in predetermined quantities. Table 10.1 gives some details of only those natural substances containing cresols, precmsors such as cymenes, derivatives such as thymol, menthol, and other allied products. 

Others. The major use of turpentine oil is as a solvent (e.g., paints) and as a starting material for the synthesis of useful chemicals such as camphor, menthol, terpin hydrate (an expectorant), a-terpineol and other fragrance compounds, and resins (adhesives, chewing gum, etc.), among others. ... 

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