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L-menthol is an organic substance. It has a cool fragrance of mint. It is soluble in organic solvents such as ethanol, acetone, ether, chloroform and benzene, and slightly soluble in water. The chemical property is relatively stable and can volatilize with steam.
Menthol is made in leaves, which is the main component of peppermint oil. It is a kind of cyclic monoterpene. It is a highly volatile essential oil produced by plants. Its components are mostly semiterpenes, monoterpenes and sesquiterpenes, especially in warm climate. Some important plant pigments are terpenoids or compounds containing terpenoid groups.
1. Menthol and racemic menthol can be used as toothpaste, perfume, flavoring agents for beverages and candies.
2. L-menthol is used as an irritant in medicine. It acts on the skin or mucous membrane and has a cooling and antipruritic effect. Its esters are used in spices and drugs.
Menthol can be purified from natural peppermint crude oil or synthesized.
The essential oil obtained from the aboveground parts (stems, branches, leaves and inflorescences) of mint, a plant of Labiatae, by steam distillation is called mint crude oil, with an oil yield of 0.5-0.6.
There are many ways to synthesize menthol:
1. Made from citronellal
Taking advantage of the property that citronellal is easy to be cyclized into isobutanol, the dextral citronellal is cyclized into levo-isobutanol with acid catalyst (such as silica gel), and the levo-isobutanol is separated and hydrogenated into levo-menthol. Its stereoisomer can be partially converted into D-citronellal by thermal decomposition and recycled.
2. Made from thymol
In the presence of m-cresol aluminum, m-cresol is alkylated to form thymol. All four pairs of menthol stereoisomers were obtained by catalytic hydrogenation (i.e. racemic menthol; racemic neomenthol; racemic isomenthol and racemic neoisomenthol). Distill it, cancel the menthol fraction, and repeatedly recrystallize it after producing the ester for isomer separation and optical resolution. The isolated levo-menthol ester is saponified to obtain menthol.
L-menthol is an organic substance. It has a cool fragrance of mint. It is soluble in organic solvents such as ethanol, acetone, ether, chloroform and benzene, and slightly soluble in water. The chemical property is relatively stable and can volatilize with steam.
Menthol is made in leaves, which is the main component of peppermint oil. It is a kind of cyclic monoterpene. It is a highly volatile essential oil produced by plants. Its components are mostly semiterpenes, monoterpenes and sesquiterpenes, especially in warm climate. Some important plant pigments are terpenoids or compounds containing terpenoid groups.
1. Menthol and racemic menthol can be used as toothpaste, perfume, flavoring agents for beverages and candies.
2. L-menthol is used as an irritant in medicine. It acts on the skin or mucous membrane and has a cooling and antipruritic effect. Its esters are used in spices and drugs.
Menthol can be purified from natural peppermint crude oil or synthesized.
The essential oil obtained from the aboveground parts (stems, branches, leaves and inflorescences) of mint, a plant of Labiatae, by steam distillation is called mint crude oil, with an oil yield of 0.5-0.6.
There are many ways to synthesize menthol:
1. Made from citronellal
Taking advantage of the property that citronellal is easy to be cyclized into isobutanol, the dextral citronellal is cyclized into levo-isobutanol with acid catalyst (such as silica gel), and the levo-isobutanol is separated and hydrogenated into levo-menthol. Its stereoisomer can be partially converted into D-citronellal by thermal decomposition and recycled.
2. Made from thymol
In the presence of m-cresol aluminum, m-cresol is alkylated to form thymol. All four pairs of menthol stereoisomers were obtained by catalytic hydrogenation (i.e. racemic menthol; racemic neomenthol; racemic isomenthol and racemic neoisomenthol). Distill it, cancel the menthol fraction, and repeatedly recrystallize it after producing the ester for isomer separation and optical resolution. The isolated levo-menthol ester is saponified to obtain menthol.
