CAS number：2216-51-5
molecular formula：C10H20O
molecular weight：156.27
EINECS number：218-690-9

English synonyms

(1R-(1-alpha,2-beta,5-alpha))-5-Methyl-2-(1-methylethyl)cyclohexanol;(1r,3r,4s)-(-)-mentho;(1R,3R,4S)-(-)-MENTHOL;(R)-(-)-Menthol;Emtricitabine Impurity 31;Natural Menthol Crystal;L-Meng alcohol Natural menthol Menthol (L);DL-Menthol menthol crystal extract

Related categories

Spices; food additives; food flavors; edible flavors (flavor enhancers); natural equivalent flavors and artificial flavors; other oxygenated compounds; pharmaceutical excipients; raw materials; Standards; other reagents; plant extracts; organic building blocks; plant extract standards; alcohols; gas chromatography standards (color scale); food and beverage standards; phosphine ligands; chemicals; pharmaceutical raw materials; menthol; other pharmaceuticals Class; Raw Materials; Organic Chemicals; Monomer Fragrance; Biochemical Reagents - Other Chemical Reagents; Medical Raw Materials - Raw Materials; Organics; chiral; Biochemistry; Terpenes; Terpenes (Others); ;Flavors and Fragrances;Small Molecule Inhibitors;Inhibitors;Small Molecule Inhibitors,Natural Products;Organophosphorus;Biochemical Reagents;API;Reference Substances-Traditional Chinese Medicine Reference Substances;Raw Materials;Other Terpenes;Chinese Medicine Reference Substances;Impurity Reference Substances;Chemical Raw Materials ;General Biochemical Reagents-Lipids;General Biochemical Reagents-Natural Products;Daily Chemical Raw Materials;Medical Raw Materials;Pharmaceutical Raw Materials;2216-51-5

Introduction

Colorless needle-like crystals with cool mint aroma. Relative density d1515=0.890, melting point 41～43℃, boiling point 216℃, 111℃(2.67kPa), specific optical rotation αD20=-49.3°, refractive index nD20=1.4609. Soluble in organic solvents such as ethanol, acetone, ether, chloroform and benzene, slightly soluble in water. The chemical properties are relatively stable and can volatilize together with steam. Rat oral LD503.3g/kg, ADI0 ~ 0.2mg/kg (FAO/WHO, 1994).

Chemical properties

Colorless needle-like crystals with cool mint aroma. Relative density d1515=0.890, melting point 41～43℃, boiling point 216℃, 111℃(2.67kPa), specific optical rotation αD20=-49.3°, refractive index nD20=1.4609. Soluble in organic solvents such as ethanol, acetone, ether, chloroform and benzene, slightly soluble in water. The chemical properties are relatively stable and can volatilize together with steam. Rat oral LD503.3g/kg, ADI0 ~ 0.2mg/kg (FAO/WHO, 1994). 

Use

●  Menthol is an edible spice that is allowed to be used in my country, and is mainly used for flavoring toothpaste, candy, and beverages. The dosage is based on normal production needs, generally 1100mg/kg in chewing gum; 400mg/kg in candy; 130mg/kg in baked food; 68mg/kg in ice cream; 35mg/kg in soft drinks.

●  GB 2760-1996 stipulates that natural thin jiannao is a permitted edible spice. GB 2760-2001 stipulates that dl-type thin film brain is also a permitted food spice. For the preparation of mint-type spices (can account for 10% to 18%), can also be used for candy (mint, gum), beverages, ice cream, etc. (the dosage is 0.054% to 0.1%).

●  Both menthol and racemic menthol can be used as flavoring agents in toothpaste, perfume, beverage and candy. It is used as a stimulant in medicine, acting on the skin or mucous membranes, and has the effect of cooling and relieving itching; orally, it can be used as a carminative medicine for headache and inflammation of the nose, pharynx, and throat. Its esters are used in fragrances and medicines. In the world, my country and Brazil are the main producers of natural mint, and the annual output of mint oil both reaches 2000-3000t.

●  The main component of peppermint oil. It is widely used in confectionery, cosmetics and toothpaste due to its characteristic mint flavor and cooling effect.

Production method

●  Menthol can be purified from natural mint crude oil and can also be prepared by synthetic method. The essential oil obtained by steam distillation of the aerial parts (stems, branches, leaves and inflorescences) of the Lamiaceae plant mint is called mint crude oil, and the oil yield is 0.5-0.6. There are various methods of synthesizing the thin hemispheres. 1. Manufacture from citronellal Utilize the property of citronellal to be easily cyclized into isopulegol, cyclize D-citronellal into L-isopulegol with an acid catalyst (such as silica gel), and separate L-isopulegol , hydrogenated to produce L-mint. Its stereotutor structure can be partially converted into D-citronellal by thermal cracking, which can be recycled. 2. Manufactured from thymol In the presence of aluminum m-cresol, m-cresol is alkylated to generate thymol. Catalytic hydrogenation yields all four pairs of menthol stereoisomers (ie, racemic menthol, racemic neomenthol, racemic isomenthol, and racemic neoisomenthol). It is distilled to remove the spin-menthol fraction, and the ester is produced and recrystallized repeatedly to separate and optically resolve the isomers. The separated L-menthol ester can be saponified to obtain menthol.

●  The l-type is obtained by cooling, crystallization and separation of natural mint crude oil. Peppermint oil contains 50% to 60% of menthol, cooled to 15°C, menthol is crystallized out, centrifuged, the oil is cooled to 5°C again, and menthol is obtained, then cooled to -10°C, and menthol is obtained again, three times 50% of menthol can be removed (about 50% of menthol remains).
L-menthol can be prepared from l-menthol. Using the residual oil obtained by the above method, the terpenes (about 20% to 25%) were distilled off under reduced pressure, and the rest was dissolved in 96% ethanol, and then reduced to menthol with metal sodium.
The synthetic product (dl-) is obtained from aromatic aromatic aldehydes.

●  Menthol is naturally present in peppermint oil, the content is as high as 80%, and menthol can be isolated from peppermint oil in industry. The crude menthol is frozen to -20°C, and the crystalline crude menthol is separated; the mother liquor is further frozen to -40°C, and a part of the crude menthol can also be separated. Crude menthol is melted by heating, dehydrated under reduced pressure, and filtered while hot. Cool to about 0°C, stand for 7-9 days, separate out crystals, dry at 42°C for 24h, and air to room temperature to obtain the finished product.

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