Neomenthol

Menthol

Names
Preferred IUPAC name 5-Methyl-2-(propan-2-yl)cyclohexan-1-ol
Other names 2-Isopropyl-5-methylcyclohexan-1-ol 2-Isopropyl-5-methylcyclohexanol 3-p-Menthanol Hexahydrothymol Menthomenthol Peppermint camphor
Identifiers
CAS Number	2216-51-5 (chiral) N 89-78-1 (racemic) N
3D model (JSmol)	Interactive image
ChEBI	CHEBI:15409 Y
ChEMBL	ChEMBL470670 Y
ChemSpider	15803 Y
DrugBank	DB00825 Y
ECHA InfoCard	100.016.992
IUPHAR/BPS	2430
PubChem CID	16666
RTECS number	OT0350000, racemic
UNII	BZ1R15MTK7 (chiral) N YS08XHA860 (racemic) N
InChI InChI=1S/C10H20O/c1-7(2)9-5-4-8(3)6-10(9)11/h7-11H,4-6H2,1-3H3/t8-,9+,10-/m1/s1 Y Key: NOOLISFMXDJSKH-KXUCPTDWSA-N Y InChI=1S/C10H20O/c1-7(2)9-5-4-8(3)6-10(9)11/h7-11H,4-6H2,1-3H3/t8-,9+,10-/m1/s1 Key: NOOLISFMXDJSKH-KXUCPTDWSA-N
SMILES O[C@H]1[C@H](C(C)C)CC[C@@H](C)C1
Properties
Chemical formula	C10H20O
Molar mass	156.27 g·mol−1
Appearance	White or colorless crystalline solid
Density	0.890 g·cm−3, solid (racemic or (−)-isomer)
Melting point	36–38 °C (97–100 °F; 309–311 K) racemic 42–45 °C, (−)-isomer, α crystalline form
Boiling point	212 °C (414 °F; 485 K)
Solubility in water	Slightly soluble, (−)-isomer
Hazards
Main hazards	Irritant, flammable
Safety data sheet	See: data page External MSDS
R-phrases (outdated)	R37/38, R41
S-phrases (outdated)	S26, S36
Flash point	93 °C (199 °F; 366 K)
Related compounds
Related alcohols	Cyclohexanol, Pulegol, Dihydrocarveol, Piperitol
Related compounds	Menthone, Menthene, Thymol, p-Cymene, Citronellal
Supplementary data page
Structure and properties	Refractive index (n), Dielectric constant (εr), etc.
Thermodynamic data	Phase behaviour solid–liquid–gas
Spectral data	UV, IR, NMR, MS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N  (what is YN ?)
Infobox references

Menthol is an organic compound made synthetically or obtained from corn mint, peppermint, or other mint oils. It is a waxy, crystalline substance, clear or white in color, which is solid at room temperature and melts slightly above.

The main form of menthol occurring in nature is (−)-menthol, which is assigned the (1R,2S,5R) configuration. Menthol has local anesthetic and counterirritant qualities, and it is widely used to relieve minor throat irritation. Menthol also acts as a weak kappa opioid receptor agonist.

Natural menthol exists as one pure stereoisomer, nearly always the (1R,2S,5R) form (bottom left corner of the diagram below). The eight possible stereoisomers are:

In the natural compound, the isopropyl group is in the trans orientation to both the methyl and hydroxyl groups. Thus, it can be drawn in any of the ways shown:

The (+)- and (–)-enantiomers of menthol are the most stable among these based on their cyclohexane conformations. With the ring itself in a chair conformation, all three bulky groups can orient in equatorial positions.

The two crystal forms for racemic menthol have melting points of 28 °C and 38 °C. Pure (−)-menthol has four crystal forms, of which the most stable is the α form, the familiar broad needles.