Estragole

In short

Estragole, also called methyl chavicol, is a phenylpropene and the main constituent of tarragon and many basil oils. It has a sweet anise-tarragon odour.

What Estragole smells like

Estragole (methyl chavicol), an isomer of anethole, has an odour reminiscent of anise but different in character: fresh, green and spicy, greener and more pungent than anethole and more herbal, with a faintly medicinal or camphoraceous edge at high concentration. A fragrance review describes it, against anethole, as more bitter, fresh-herbaceous and phenolic. It is the main constituent of tarragon oil and is abundant in basil. IFRA limits it because of genotoxicity concerns.

Leading note: Green herbal anise
Clear facets: Tarragon
Supporting facets: Basil
Faint facets: Phenolic, bitter
Character: Fresh, green, pungent, herbal

What makes Estragole distinctive

Anise made green: the tarragon-basil version of the anise note, less sweet and more pungent than anethole.

Concentration and dilution

At high concentration a faintly medicinal, camphoraceous edge can appear.

How Estragole is used

Used in herbal and anisic accords and in tarragon and basil reconstructions; IFRA restricts it.

Typical role: modifier (used in small amounts to change the character of a blend).

How Estragole differs from similar materials

Anethole: Anethole is the sweeter, purer anise; estragole is greener, more pungent, herbal and bitter. (compared directly by a cited source)
Basil Oil: Exotic basil is estragole-led, adding herbaceous, green and spicy notes to its anise. (compared directly by a cited source)
Tarragon Oil: Tarragon oil is mostly estragole, with a green, herbaceous, celery-like edge. (compared directly by a cited source)

An asterisk marks a difference that a cited source states directly. The others compare the published descriptions of each material. Smell varies with grade, supplier and dilution; compare them side by side on blotters before substituting one for another.

Formulation considerations

Covered by an IFRA Standard, which also counts estragole contributed by natural oils. Check the limit for your product category.

Identity and classification

Type: Aroma chemical
Origin: Occurs in nature
Odour family: Aromatic / Green
Note position: Top to heart note
Physical form at room temperature: Liquid
Also known as: Methyl chavicol, 4-Allylanisole
CAS number: 140-67-0
Molecular formula: C10H12O
Molecular weight: 148.2 g/mol
IUPAC name: 1-methoxy-4-prop-2-enylbenzene

The CAS number, formula and molecular weight are taken from PubChem compound 8815, whose own record lists this CAS number; checked 19 October 2026.

Safety and compliance

The IFRA Standards Library lists a Standard covering Estragole:

"Estragole" — Restriction, 51st Amendment, published 2023-06

Limits differ by product category and are set out in the Standard itself; this page does not reproduce them. The list above reflects the library as read on 19 October 2026.

Hazard classification of the neat substance, as PubChem summarises it, read 26 October 2026. Companies notifying the ECHA C&L Inventory classify it (1,959 reports): H302 harmful if swallowed (99.8% of reports); H317 may cause an allergic skin reaction (99.3% of reports); H341 suspected of causing genetic defects (98.4% of reports); H351 suspected of causing cancer (98.4% of reports); H315 causes skin irritation (11% of reports); H412 harmful to aquatic life with long lasting effects (10.6% of reports). 1 of the reports find it does not meet the hazard criteria. A skin sensitiser classification concerns handling the neat material and the dose in a finished product; the IFRA Standards, where they apply, set the limits. Unless it is harmonised, this is the notifiers' own classification, not a binding one.

This page is general information, not a safety assessment or a specification. Confirm identity, composition, IFRA status and allergen content from your supplier's documents for the lot you hold.

Materials it works with

Tarragon Oil
Essential oil · Aromatic / Spicy — aniseed, herbal, green, sweet
Basil Oil
Essential oil · Aromatic / Spicy — herbal, green, aniseed, fresh
Anethole
Aroma chemical · Aromatic / Spicy — anise, licorice, sweet, herbal
Linalool
Aroma chemical · Floral / Citrus — floral, fresh, woody, citrus

Estragole is also suggested as a partner on the pages for Dihydroanethole.

Used in formulas and accords

Not currently used in any published formula.

The Formula & Accord Library lists Estragole here as soon as a published formula, accord or base uses it.

Questions about Estragole

Is Estragole natural or synthetic?

The molecule occurs in nature. Commercial Estragole may be made by synthesis or obtained from natural sources, so check the supplier's specification if the distinction matters to you.

What is the CAS number of Estragole?

140-67-0. It was checked against PubChem on 19 October 2026.

Is Estragole covered by an IFRA Standard?

Yes. The IFRA Standards Library lists a Standard covering it: "Estragole" — Restriction, 51st Amendment. The limits depend on the product category; read the Standard itself before formulating.

Sources

PubChem — compound 8815, checked 19 October 2026.
PubChem — GHS classification (the ECHA C&L Inventory notifications and any harmonised EU entry), read 26 October 2026.
IFRA — Standards Library, read 19 October 2026.
Premiere Peau — Estragole — published perfumery reference.
ChemicalBook — estragole (CAS 140-67-0) — odour database.
Yes We Lab — laboratory analysis of estragole — published literature.
Olfactory profile: the RUŌOD Lab team's synthesis of the published descriptions above, reviewed 21 October 2026. Evidence: more than one published description. Classification and the short description: revision 1. Descriptions of odour are judgement, not measurement.