Thymol (CAS: 89-83-8): Chemical Properties, Production Process, and Applications

What Is Thymol?

Thymol, CAS 89-83-8, chemically 2-isopropyl-5-methylphenol, is a naturally occurring monoterpene phenol found in the essential oils of thyme (Thymus vulgaris) and related plants. It is a white crystalline solid with a strong, characteristic thyme-like aroma and well-known antimicrobial and antioxidant properties, and it is used in oral care, flavours and fragrances, cosmetics, animal feed and other applications.

This guide covers the chemistry, specification, properties, production, antimicrobial basis and applications of thymol, its comparison with related phenolics, dosage, quality and regulatory points, and supply. PolyBlueChem supplies thymol from REACH-registered sources for the EU market, with per-batch COA and SDS.

CAS number	89-83-8
Chemical name	2-Isopropyl-5-methylphenol
Synonyms	Thymol; 5-methyl-2-isopropylphenol; thyme camphor; 2-isopropyl-5-methylphenol
Molecular formula	C₁₀H₁₄O
Molecular weight	150.22 g/mol
Appearance	White crystals or crystalline powder
Type	Monoterpene phenol (natural or synthetic)

Chemistry and Structure

Thymol is a phenol: a benzene ring carrying a hydroxyl group (-OH), flanked by an isopropyl group and a methyl group. The hydroxyl group is the functional heart of the molecule:

The phenolic -OH makes thymol weakly acidic (it forms salts with bases) and gives it its antioxidant and antimicrobial behaviour.
The isopropyl and methyl groups are electron-donating and sterically bulky; they increase lipophilicity and make the phenol hindered, which shapes how it interacts with cell membranes and with radicals.
The placement of the two alkyl groups distinguishes thymol from its close isomer carvacrol (2-methyl-5-isopropylphenol), which differs only in the relative positions of the methyl and isopropyl groups.

Compound	CAS	Structure	Relationship
Thymol	89-83-8	2-isopropyl-5-methylphenol	–
Carvacrol	499-75-2	2-methyl-5-isopropylphenol	Positional isomer of thymol
p-Cymene	99-87-6	1-isopropyl-4-methylbenzene	Biosynthetic precursor / related hydrocarbon

Specifications

Thymol is supplied as white crystals or crystalline powder to the following specification:

Parameter	Specification
Colour / appearance	White crystals or crystalline powder
Aroma	Strong, characteristic (thyme-like)
Content	98% min
Melting point	49 °C min
Solubility (25 °C)	1 g dissolves completely in 3 ml of 80% ethyl alcohol

A specification sheet and a per-batch certificate of analysis (COA) are available on request.

Physical and Chemical Properties

Property	Value / behaviour
Form	White crystals or crystalline powder
Molecular weight	150.22 g/mol
Melting point	About 49 – 51 °C
Boiling point	About 232 °C
Density	About 0.99 g/cm³
Solubility	Soluble in alcohol, ether and acetone; slightly soluble in water
Acidity	Weakly acidic phenolic -OH; forms salts with bases
Stability	Stable in normal storage; can oxidise on exposure to light, heat and air

Thymol’s relatively high melting point (it is a solid at room temperature) and its lipophilic, volatile character explain both its handling (crystalline solid) and its behaviour in formulation (readily dispersed in oils, alcohols and fats).

How Thymol Is Produced

Thymol is obtained either by extraction from thyme oil or by synthesis. Both are commercial routes, chosen on cost, volume and the natural/synthetic claim.

Route	Principle	Notes
Natural extraction	Steam distillation of thyme (or oregano-type) oil, then crystallisation/fractionation	Thyme oil is rich in thymol; the crystallised product is purified to specification
Synthetic (from m-cresol)	Friedel-Crafts alkylation of m-cresol with propylene	The main commercial synthetic route to thymol
Synthetic (from p-cymene)	Conversion of p-cymene to thymol (via oxidation or sulfonation-type routes)	An alternative route from a terpene feedstock

Extraction – thyme plant material is steam-distilled; the essential oil is condensed and separated, and thymol is isolated by crystallisation (thymol crystallises readily because its melting point is near 50 °C) or by fractional distillation.
Synthesis from m-cresol – m-cresol is alkylated with propylene under acid catalysis (a Friedel-Crafts reaction); the positional selectivity of the alkylation gives thymol. The product is purified by distillation/recrystallisation.
Purification – whether natural or synthetic, the crude thymol is purified to reach the specified content and melting point.

Because the buyer’s specification fixes the content (98% min) and melting point (49 °C min), both natural and synthetic routes must deliver a product of comparable purity. Natural thymol is often preferred where a “natural” claim matters; synthetic thymol where volume and cost dominate.

The Antimicrobial Basis

Thymol is well known for its antimicrobial activity against a broad range of bacteria and fungi. The mechanism is generally attributed to its phenolic structure:

The lipophilic thymol molecule partitions into microbial cell membranes.
The phenolic -OH disrupts membrane integrity and function, increasing permeability and causing leakage of cell contents.
The result is inhibition of microbial growth – the basis for thymol’s use in preservative, oral-care and antimicrobial formulations.

Thymol is also an antioxidant (a hindered phenol that scavenges radicals, like other phenolic antioxidants). These two properties – antimicrobial and antioxidant – explain most of its applications. (This section describes measurable properties of the ingredient; it is not medical or veterinary advice.)

Applications by Industry

Industry	Role of thymol
Oral care	A classic oral-care phenol in mouthwash, toothpastes and rinses
Flavours and fragrances	A herbaceous, thyme-like note in flavour and fragrance compositions
Cosmetics and personal care	Aromatic and preservative-support ingredient
Animal feed	Aroma/flavour ingredient, where permitted
Food preservation	Antimicrobial preservative, where permitted
Industrial / other	Phenolic intermediate; antimicrobial formulations; laboratory use

Oral care – thymol is one of the classic essential-oil phenols used in mouthwash and oral rinses.
Flavours and fragrances – its strong thyme-like note is used in flavour and fragrance compositions.
Cosmetics and personal care – used for its aroma and antimicrobial (preservative-support) properties.
Animal feed – used as an aroma/flavour ingredient, where permitted by the market.

Thymol vs Other Natural Antimicrobials

Compound	CAS	Type	Character	Typical use
Thymol	89-83-8	Monoterpene phenol	Strong aroma; crystalline solid; antimicrobial + antioxidant	Oral care, flavours, preservative
Carvacrol	499-75-2	Monoterpene phenol (isomer)	Similar activity; liquid at room temp.	Antimicrobial/flavour, feed
Eugenol	97-53-0	Phenylpropanoid phenol	Clove aroma; antimicrobial	Flavour/fragrance, dental
Menthol	2216-51-5	Monoterpene alcohol	Cooling, minty; not a phenol	Oral care, flavours, cooling
Sorbic acid / benzoates	–	Organic acid / salt preservatives	Classic food preservatives	Food preservation

Guidance: choose thymol where a natural phenolic with a strong, market-accepted aroma and antimicrobial/antioxidant properties is wanted; choose carvacrol for a liquid isomer; use menthol where a cooling sensation (not antimicrobial action) is the goal.

Dosage and Formulation Notes

Application	Starting-point guidance
Oral care	A small fraction of a percent, set by the formulation and taste
Flavours	Very low levels, set by the flavour profile
Cosmetics	Low levels, within permitted use and set by sensory/stability testing
Preservative/antimicrobial use	Set by the required antimicrobial effect and by the permitted level in the market

Thymol is crystalline and intensely aromatic, so it is dissolved in an appropriate solvent (alcohol, oil) before use and kept at low levels. Confirm the level by antimicrobial/stability testing and against the permitted limits for your market.

Quality, Standards and Regulatory

Point	Note
Identity/purity	Confirmed by content (98% min) and melting point (49 °C min) on the COA
REACH	Thymol is supplied from REACH-registered sources for the EU market
Flavour/food use	Where used as a flavouring or preservative, confirm the permitted use and level for your market
Feed/cosmetic use	Confirm the permitted use for the specific application and market

Always confirm the grade and the permitted use for your application and market before ordering.

Safety, Handling and Storage

Irritant – thymol is a phenolic and can irritate skin, eyes and mucous membranes; avoid contact and use protective equipment.
Dust/vapour – handle with ventilation; avoid breathing the powder or concentrated vapour.
Storage – keep sealed, cool and dry, away from light, heat and oxidisers; thymol can oxidise (darken) if exposed to air and light.
Segregation – store away from strong oxidisers and other strongly odorous materials.

Packaging, Logistics and Supply

Item	Standard options
Packaging	25 kg fibre drums or as agreed; keep sealed
Documentation	Per-batch COA and SDS; REACH documents on request
Incoterms	FOB and CIF
Storage	Sealed, cool and dry, away from light

Thymol price depends on the essential-oil feedstock (thyme/oregano) and on the synthetic route from cresol; the natural and synthetic markets move somewhat independently. Buying on committed tonnage, and confirming the REACH position for the EU, gives the best terms.

Thymol in Oral Care and Mouthwash

Thymol is one of the classic phenols of oral care, and mouthwash is its best-known home. Aromatic and antimicrobial, it gives both a herbaceous taste and a functional contribution to the product.

Product	Role of thymol
Mouthwash / oral rinse	Aromatic, antimicrobial phenolic component
Toothpaste	Flavour and antimicrobial contribution
Gargles and throat rinses	Thyme-like flavour with antimicrobial properties

In these products thymol works alongside other essential-oil components (for example menthol or eucalyptol) to build an aromatic, antimicrobial oral-care system. Levels are low and set by taste and by the antimicrobial requirement.

Thymol in Food, Feed and Preservation

Thymol’s antimicrobial activity makes it useful wherever microbial spoilage is a concern – provided the use is permitted in the market.

Application	Role of thymol
Food flavouring	Herbaceous thyme note
Food preservation	Antimicrobial preservative, where permitted
Animal feed	Aroma/flavour and preservative-support, where permitted

As a natural phenolic, thymol fits the trend toward natural flavour and preservative ingredients. Because food and feed uses are regulated, the grade and the permitted level must be confirmed for each market before use.

Thymol in Cosmetics and Personal Care

Category	Role of thymol
Skin care	Aromatic, antimicrobial (preservative-support) ingredient
Hair care	Herbaceous aroma and preservative support
Soaps and washes	Aroma and antimicrobial contribution
Fragrance	Herbal, spicy note

In cosmetics, thymol is used for its distinctive aroma and its antimicrobial character, which supports preservation. As with all cosmetic ingredients, the use level must sit within the permitted limits for the market, and stability/sensory testing confirms the level.

Market, Sourcing and Natural vs Synthetic

Natural route – begins with thyme/oregano essential oil; supply follows the botanical crop and supports a “natural” positioning.
Synthetic route – begins with m-cresol (and propylene) or p-cymene; supply follows the petrochemical/cresol market and can scale independently of the harvest.
Price drivers – the essential-oil feedstock for natural thymol versus the cresol feedstock for synthetic; freight and energy also matter.
REACH and market access – for the EU, confirm the REACH-registered source and the documentation.

Choosing between natural and synthetic thymol is mainly a question of specification, cost and positioning: where a natural claim matters, the natural route is used; where volume and cost dominate, the synthetic route is used. Either way, buy against the content and melting-point specification.

Frequently Asked Questions about Thymol

What is thymol?

Thymol (CAS 89-83-8) is 2-isopropyl-5-methylphenol, a monoterpene phenol with a strong thyme aroma and antimicrobial/antioxidant properties.

What is the CAS number of thymol?

89-83-8; the formula is C₁₀H₁₄O.

Is thymol natural or synthetic?

Both: it is extracted from thyme oil and also produced synthetically (for example from m-cresol and propylene).

What is the difference between thymol and carvacrol?

They are positional isomers (both C₁₀H₁₄O); the methyl and isopropyl groups are swapped. Carvacrol is a liquid at room temperature, thymol a solid.

Is thymol REACH-registered?

It is available from REACH-registered sources for the EU market.

How is thymol stored?

Sealed, cool and dry, away from light and oxidisers.

How is it packed?

25 kg fibre drums (or as agreed), with per-batch COA and SDS.