General Description
White crystalline solid with a peppermint odor and taste.
Reactivity Profile
D,L-MENTHOL(89-78-1) is incompatible with butyl chloral hydrate, camphor, phenol, chloral hydrate, Exalgine, betanaphthol, resorcinol or thymol in triturations; potassium permanganate, chromium trioxide and pyrogallol. D,L-MENTHOL(89-78-1) is also incompatible with strong oxidizers.
Air & Water Reactions
Insoluble in water.
Hazard
Irritant to mucous membranes on inhalation.
Fire Hazard
This chemical is combustible.
Description
Menthol has a mint-like odor and a fresh, cooling taste. It may be
prepared by hydrogenation of thymol.
Physical properties
Appearance: colorless or white acicular prismatic crystals or white crystalline powder. Solubility: easily dissolved in ethanol, chloroform, ether, liquid paraffin, or
volatile oil and soluble in water. Odor: a cool, refreshing, and pleasant mint aroma,
sweet odor, and taste cool early after burning. Boiling point: 212?°C. Melting point:
41–43?°C. Specific optical rotation: ?49 to ?50°.
Occurrence
Reported found in peppermint and other mint oils (e.g., M. arvensis), lemon peel oil, cranberry, pineapple, cab bage, thymus, egg, rum, cocoa, tea, honey, avocado, coriander, mango, rice, litchi, dill herb, calamus, juniper berries, fennel, buchu
oil, clam and Roman chamomile oil, Mentha species.
History
In the world of aromatic chemicals, menthol is often described as a unique source
of skin and mucous membranes. Menthol is mainly extracted from natural plants.
The vast majority of natural menthol in the global market is extracted from numerous Asian mint. In 2006, the world’s natural menthol production is 12,800?tons or
more. However, due to various factors, the production of natural menthol is becoming less and less. Since the 1960s, Japan, Germany, and other countries had developed the synthetic menthol products. In 1974 the German company Symrise and
Japan Takasago Fluidic Systems company launched chemical synthesis of menthol.
At present, attention has been paid to the study of menthol analogy substances and
the effect of the changes of molecular structure on the aroma and cool sensation.
Some studies have shown that hydroxyl groups located in the branched or 1, 4 chain
cannot show a sense of cool. The researchers believed that menthol analogy substances with optical activity should be able to show different, surprising cooling
effect, and the structure of hydroxyl alkyl groups is the key point to have a cooling
effect. The Japanese chemist Ryoji Noyo and his colleagues found that in
BINAP and rhodium complexes as catalysts for asymmetric hydrogenation reaction, the synthesis of menthol is very effective. Because of the contribution of asymmetric organic synthesis, they won the 2001 Nobel Prize in Chemistry.
Definition
ChEBI: P-menthan-3-ol is any secondary alcohol that is one of the eight possible diastereoisomers of 5-methyl-2-(propan-2-yl)cyclohexan-1-ol. It has a role as a volatile oil component. It is a p-menthane monoterpenoid and a secondary alcohol.
Indications
For external application, it is applied locally and often used to relieve pain and itching. A nasal drip is used in the head cold. Inhalation or spray is used for sore throat.
Oral administration can promote digestion.
Preparation
By hydrogenation of thymol.
Aroma threshold values
Detection: 950 ppb to 2.5 ppm; aroma characteristics at 1.0%: cooling menthol with a penetrating minty
eucalyptus note.
Taste threshold values
Taste characteristics at 25 ppm: cooling, camphoreous, minty with a clean eucalyptus note.
Flammability and Explosibility
Notclassified
Biochem/physiol Actions
Menthol exhibits antifungal action on the membrane permeability and the cell wall consistency, this might leads to cell death or inhibition of the C. albicans filamentation. Therefore, it can be used as a potential therapeutic agent for candidiasis. In addition to antifungal activity, menthol also exhibits anesthetic, antispasmodic, anti-ulcer and antiviral properties. It is considered as a safe compound for animal life. Therefore, Menthol is widely used in pharmaceuticals, cosmetics and food industries.
Pharmacology
Menthol has a wide range of pharmacological effects. Menthol can stimulate the
nerve endings of skin and slowly penetrate into the skin, resulting in prolonged
congestion and reflex caused by deep vascular changes, adjusting the vascular function, and achieving therapeutic effects in topical application. Topical application of
compound has anti-inflammatory, analgesic, and anesthetic effects.
In respiratory system: For treatment of bronchitis, it could reduce the respiratory
tract foam sputum and increase the effective ventilation cavity road. For treatment
of rhinitis and laryngitis, it exerts mitigation by promoting secretion and diluting
viscous mucus.
In digestive system: Menthol showed the powerful effect on bile.
In central nervous system: A small amount of peppermint can stimulate the central nervous system through the peripheral nerve to expand the skin capillaries, promote the secretion of sweat glands, increase heat dissipation, and show sweating
antipyretic effect.
In addition, menthol has penetration-enhancing effect on many kinds of drugs;
the mechanism is related to the changes of the ultrastructure of the skin, which is
expected to be widely used in transdermal drug delivery agents. In vitro experiments, it had strong antibacterial activity against Staphylococcus aureus and
Bacillus proteus. Recently, British scientists found that mint leaves can prevent cancer lesions in the blood vessel growth to decrease blood supply for, showing a certain anti-tumor effect
Clinical Use
It can be clinically used to assist anesthesia, postoperative analgesia, intercostal
nerve block, trigeminal nerve block, occipital nerve block, and so on. When applied
locally, it can promote blood circulation, diminish inflammation, relieve itching,
relieve pain, relieve edema, and so on.
