A kind of cockroach, also known as menthol. Molecular formula C10H20O, L-menthol is a colorless transparent needle crystal; melting point 44 ° C, boiling point 216.4 ° C, specific optical rotation -48 °; slightly soluble in water, soluble in ethanol, ether, acetone, chloroform. Racemic menthol is a colorless transparent needle crystal; melting point 38 ° C, boiling point 216 ° C; soluble in ethanol, ether, acetone, benzene. Hydrogenation of menthol to p-alkane; oxidation or catalytic dehydrogenation with chromic acid to give menthone; racemic menthol can be resolved by benzoate. Menthol can be isolated from peppermint oil or from citronellal or thymol. Menthol is an important spice. Due to its cooling effect, L-menthol is widely used in cigarettes, cosmetics, toothpaste, chewing gum, sweets and medicines, and rubbing agents [to exert local itching, pain relief, and cooling (mechanism: stimulating cold receptors on the skin but not causing actual temperature changes) ) and a slight local anesthetic, etc., also play a role in promoting penetration. Synthetic menthol is a mixture of various isomers and is of little value.
Menthol is produced in the leaves, which is the main component of peppermint oil, and is a kind of ring-shaped monoterpene. It is a highly volatile essential oil produced by plants. Its ingredients are mostly semi-anthracene, monoterpenes and sesquiterpenes, especially when the climate is warm. Some important plant pigments are terpenoid- or steroid-containing compounds.
Molecular formula and molecular weight
C10H20O, 156.27 [CAS NO.]: 89-78-1
Physical Properties
Appearance: White crystal
Pharmacological action: Itching, pain relief, antiseptic, irritation, anesthesia, cooling and anti-inflammatory effects, can cure headache, neuralgia, itching and respiratory inflammation, atrophic rhinitis,
hoarseness , etc. Molecular formula: C10H20O
Molecular mass: 156.26
Boiling point: 212 ° C.
Melting point: 41-43 ° C
colorless needle crystal or granular. The temperature of 41-43 ° C (42-45 ° C), the boiling point of 216.5 ° C, the relative density of 0.890 (15 / 15 ° C), the refractive index of 1.458. Soluble in alcohol; chloroform; ether; glacial acetic acid; liquid paraffin and petroleum ether, slightly soluble in water. Menthol contains three asymmetric carbon atoms, four spatial cis and trans isomers are known, each of which has a right-handed form; a left-handed form and a racemic form. L-menthol has a minty character and a cooling effect. Racemic menthol ([89-78-1]) also has a cooling effect, and other isomers have no cooling effect.
Uses: Menthol and racemic menthol can be used as a scenting agent for toothpaste, perfume, beverages and confectionery. It is used as a stimulant in medicine and acts on the skin or mucous membranes. It has a cooling and antipruritic effect. Oral administration can be used for headaches and inflammation of the nose, throat and throat. Its esters are used in perfumes and pharmaceuticals. In the world, China and Brazil are the main producers of natural mint, and the annual output of peppermint oil is 2000-3000t.
