The short answer
Menthol is C10H20O, molecular weight 156.27 g/mol. The grade that matters commercially is l-menthol, CAS 2216-51-5, which is the isomer responsible for the cooling sensation.
It is a secondary alcohol built on a cyclohexane ring, it melts just above room temperature, and it sublimes slowly in the warehouse. Almost every specification problem with menthol traces back either to which isomer is in the drum or to how the crystals were stored.
Formula, molecular weight and identifiers
| Item | Value |
|---|---|
| Molecular formula | C10H20O |
| Molecular weight | 156.27 g/mol |
| IUPAC name | 5-Methyl-2-(propan-2-yl)cyclohexan-1-ol |
| CAS (l-menthol) | 2216-51-5 |
| CAS (menthol, unspecified isomer) | 89-78-1 |
| CAS (dl-menthol, racemic) | 15356-70-4 |
| EC number | 218-690-9 |
| HS code | 2906.11 |
Where the 156.27 comes from: ten carbon at 12.011, twenty hydrogen at 1.008, one oxygen at 15.999 — 120.11 + 20.16 + 16.00 = 156.27 with the standard atomic weights.
Note that three CAS numbers are in circulation for what a purchase order may simply call “menthol”. If the order says 89-78-1 and the certificate says 15356-70-4, you have bought racemic material and the cooling will be roughly half of what was expected. Always write the isomer into the order.
Why only one isomer cools
The menthol skeleton carries three stereocentres, which gives eight possible stereoisomers arranged as four pairs: menthol, neomenthol, isomenthol and neoisomenthol, each existing as a d- and an l- form.
| Isomer | Configuration | Cooling | Odour and taste |
|---|---|---|---|
| l-Menthol | (1R,2S,5S) | Strong | Clean, sweet, peppermint |
| d-Menthol | (1S,2R,5R) | Weak | Musty, less minty |
| Neomenthol | (1S,2S,5R) and enantiomer | Very weak | Harsh, slightly bitter |
| Isomenthol / neoisomenthol | Remaining four | Negligible | Off-notes, musty |
Because all eight share the formula C10H20O and the molecular weight 156.27, no elemental or mass measurement can separate them. The practical tests are optical rotation and chiral GC assay, and both belong on the certificate of analysis.
Physical properties
| Property | Value |
|---|---|
| Appearance | Colourless needle-like or prismatic crystals, or white crystalline powder |
| Odour | Strong, characteristic peppermint |
| Melting point | 36 to 38 °C (l-menthol); racemic dl-menthol melts near 34 °C |
| Boiling point | About 212 °C at atmospheric pressure |
| Density | About 0.890 g/cm3 at 25 °C |
| Solubility in water | Very slight, about 0.42 g/L at 25 °C |
| Solubility in solvents | Freely soluble in ethanol, chloroform, ether and light mineral oil; soluble in propylene glycol |
| Optical rotation (l-menthol) | About -45 to -51° (10 % w/v in ethanol, 20 °C) |
| Flash point | About 93 °C, closed cup |
Two of those numbers drive most of the handling trouble. The melting point sits only a little above a warm warehouse, so drums soften, cake and fuse in transit through the tropics. And menthol sublimes: crystals lose mass slowly to the vapour phase even well below melting, which is why partly used drums must be resealed immediately and why loose weight loss on a long voyage is normal rather than a short shipment.
How menthol produces cold without cold
Menthol does not lower temperature. It binds to TRPM8, the cold-and-menthol receptor in sensory nerve endings, and opens the same ion channel that genuine cold opens. The brain receives an identical signal and reports cold that no thermometer can find.
Three consequences follow for formulators. The effect is stereospecific, so only l-menthol gives a full response. It is concentration-dependent with a ceiling, and past roughly 1 to 2 % in a topical base the sensation turns from cooling to burning. And it desensitises with repeated exposure, which is why long-lasting cooling agents such as WS-3 and WS-23 are blended in rather than simply raising the menthol dose.
Natural and synthetic menthol
| Natural (mint-derived) | Synthetic | |
|---|---|---|
| Source | Freezing and centrifuging Mentha arvensis oil, largely from Uttar Pradesh, India | Hydrogenation of thymol, or asymmetric synthesis from myrcene or citronellal |
| Isomer | l-Menthol | l-Menthol, or dl-menthol from non-asymmetric routes |
| Typical assay | 99 % min | 99.5 % min |
| Trace profile | Carries mint oil congeners; the odour reads rounder | Very clean; consistent lot to lot |
| Supply behaviour | Crop-linked, monsoon-sensitive, price volatile | Plant-linked, steadier |
| Claim | Natural origin, and kosher or halal where certified | Nature-identical |
India crystallises the large majority of the world’s natural menthol, so an Indian origin is the ordinary case rather than a compromise. Choose natural when the label claim needs it; choose synthetic when batch-to-batch consistency or price stability matters more. In both cases specify assay, optical rotation and melting point, because “natural” on its own is not a purity statement.
Crystals, flakes and powder
- Bold crystals. Large needles, the traditional trade form. Slowest to sublime, easiest to inspect, slowest to dissolve.
- Small or fine crystals. Faster dissolution, more surface area, so more care with sealing.
- Flakes. Free-flowing and easy to dose by weight in continuous plants.
- Powder. Fastest dissolution, used in tableting and dry blends; the most prone to caking and loss.
- Pharmacopoeial grades. IP, BP, USP, EP and JP. These set assay, optical rotation, melting range, residue on ignition, heavy metals and related substances. Name the monograph in the order.
- Food and flavour grade. FCC compliant, with the usual food-contact packing and documentation.
Scapex Exports supplies menthol as l-menthol crystals and as menthol for personal care, in bold crystal, small crystal and powder forms.
What menthol is used for
- Oral care. Toothpaste, mouthwash and dental gels, for cooling and for the clean-mouth signal that users read as efficacy.
- Confectionery and tobacco alternatives. Mints, chewing gum, lozenges and cough drops.
- Pharmaceuticals. Topical analgesic balms and sprays, decongestant rubs and inhalers, antipruritic lotions.
- Personal care. Shaving preparations, after-sun and cooling gels, shampoos and scalp tonics, foot care.
- Beverages and flavours. Mint flavour systems, where it is dosed with the cooling agents that extend the effect.
- Household and industrial. Air care, cleaning fragrances and some agricultural and veterinary preparations.
Handling, packing and export documents
- Temperature. Store below 25 °C, away from direct sun and away from the container roof. Above about 30 °C crystals begin to fuse into a solid cake.
- Sealing. Menthol sublimes and is strongly odour-active. Keep drums tightly closed, reseal partial drums at once, and store away from any material that can pick up odour.
- Static and dust. The powder form is combustible as a dust; earth equipment and avoid generating clouds.
- Health. Irritating to eyes and, at high concentration, to skin and the respiratory tract. Handle with gloves and eye protection; avoid concentrated vapour in confined spaces.
- Transport. Not normally classified as a dangerous good for sea freight in crystal form; confirm the position for your destination and pack size with the forwarder.
- Packing. 25 kg fibre drums or HDPE drums with double food-grade polyethylene liners, palletised and shrink-wrapped.
An export consignment should carry a certificate of analysis stating assay, optical rotation, melting range, appearance, residue on ignition and heavy metals; a 16-section GHS safety data sheet; the pharmacopoeial or FCC compliance statement where claimed; commercial invoice and packing list; certificate of origin; and, for natural grades, the origin or non-GMO declaration your market requires.
Enquire with a specification
Menthol is supplied by Scapex Exports as a manufacturer and supplier working with qualified Indian crystallisers and synthesisers, in natural and synthetic l-menthol, in bold crystal, small crystal, flake and powder forms, against IP, BP, USP, EP, JP or FCC as required.
Send the isomer, the monograph, the crystal form, the pack size and the destination port, and you will get a quotation written against that specification rather than a generic offer — with the certificate of analysis to review before the order is placed.
Frequently asked questions
What is the chemical formula of menthol?
C10H20O — ten carbons, twenty hydrogens and one hydroxyl oxygen, giving a molecular weight of 156.27 g/mol. It is a cyclohexanol: 5-methyl-2-(propan-2-yl)cyclohexan-1-ol. The commercially important form is l-menthol, CAS 2216-51-5; the CAS number 89-78-1 covers menthol without specifying which isomer.
What is the molecular weight of menthol?
156.27 g/mol for all isomers, because they differ only in the arrangement of the same atoms in space, not in composition. That is exactly why a certificate of analysis quoting only formula and molecular weight tells you nothing about cooling performance — optical rotation and assay by chiral GC do.
Why is l-menthol the only one that cools properly?
Cooling is a lock-and-key event at the TRPM8 receptor, and only one of the eight stereoisomers fits well. l-Menthol, the (1R,2S,5S) isomer, is by far the most active; d-menthol is weakly active and the other isomers carry off-notes described as musty or bitter. Racemic dl-menthol is roughly half as effective by weight and tastes different.
Is natural menthol better than synthetic menthol?
Chemically, high-purity synthetic l-menthol and natural mint-derived l-menthol are the same molecule and perform the same. The differences that matter commercially are the trace profile, the labelling claim and the price: natural carries mint-oil congeners and a natural-origin claim, synthetic is consistent batch to batch and unaffected by monsoon-driven crop swings. Choose on the claim you need, then specify assay and optical rotation regardless.
What does optical rotation tell you on a menthol COA?
It is the quickest proof that you have l-menthol rather than a racemic or contaminated lot. l-Menthol reads roughly -45 to -51 degrees (10% w/v in ethanol, 20 degrees C, sodium D line). A reading near zero means a racemic mix; a shortfall against the range means dilution with other isomers. Put the range in the purchase order alongside assay and melting point.
What is menthol?
Menthol (CAS 89-78-1) is supplied as white crystalline needles, with the molecular formula C10H20O and a molecular weight of 156.27 g/mol. Its main applications include cooling agent for personal care. Scapex Exports exports and supplies it from India in 99.5% min USP/BP grade, with a batch Certificate of Analysis (COA) and MSDS.
What is menthol used for?
The main applications of Menthol are cooling agent for personal care.
Where to buy menthol?
You can buy Menthol from Scapex Exports, an exporter and supplier based in Ahmedabad, India. Send the grade, quantity and destination port with the Request a Quotation button on the product page and we will confirm availability, packing and price, with the COA and MSDS.