Chemical identity
- IUPAC name: 4‑allyl‑2‑methoxybenzene (also reported as 1‑allyl‑4‑methoxybenzene)
- Molecular formula: C₁₁H₁₄O₂
- Molar mass: 178.22 g mol⁻¹
- CAS Registry Number: 93‑15‑2
- Synonyms: 4‑Allyl‑2‑methoxy‑1‑methylbenzene, 2‑Methoxy‑4‑prop-2-enyl‑benzene, Methyl eugenol, 4‑allyl‑1‑methoxybenzene
Physical and chemical properties
Methyl eugenol is a colourless to pale yellow liquid with a characteristic sweet, clove‑like odor. It is sparingly soluble in water but miscible with most organic solvents (e.g., ethanol, ether, benzene). The compound is relatively stable under normal atmospheric conditions but may undergo oxidation when exposed to air and light over extended periods.
Natural occurrence
Methyl eugenol is a natural constituent of essential oils from a variety of aromatic plants, including:
- Basil (Ocimum basilicum)
- Clove (Syzygium aromaticum)
- Nutmeg (Myristica fragrans)
- Cinnamon (Cinnamomum verum)
- Citrus species (e.g., orange and lemon peel)
Its concentration in plant material can range from trace amounts to several percent of the total essential‑oil content, depending on species, cultivar, and extraction method.
Applications
| Sector | Main uses |
|---|---|
| Fragrance & flavour | Employed as a flavouring agent to impart a sweet, spicy, or clove‑like note in foods, beverages, and tobacco products; also used in perfumery for its characteristic aroma. |
| Agriculture | Utilised as an attractant in traps for certain fruit‑fly species (e.g., Bactrocera spp.) and other tephritid pests, aiding pest‑management programs. |
| Research | Serves as a reference compound in studies of plant secondary metabolites, olfactory receptors, and toxicology. |
Safety and toxicology
Methyl eugenol has been the subject of toxicological evaluation because of its potential carcinogenicity observed in rodent bioassays. Key points include:
- Acute toxicity: Low acute toxicity; oral LD₅₀ values in rodents are in the range of several grams per kilogram body weight.
- Chronic exposure: Long‑term animal studies have reported increased incidence of tumours in specific organs (e.g., liver and forestomach) at high dietary doses.
- Human health assessment: International regulatory agencies (e.g., the U.S. Food and Drug Administration, the European Food Safety Authority) consider methyl eugenol a food additive of concern and have established maximum permitted levels in certain food categories. In the United States, the FDA classifies it as “generally recognized as safe” (GRAS) only when present incidentally in food; intentional addition is restricted.
- Occupational exposure: Workers handling methyl eugenol in manufacturing or laboratory settings should employ standard protective equipment (gloves, goggles, adequate ventilation) to minimise inhalation and skin contact.
Regulatory status
| Jurisdiction | Status |
|---|---|
| United States (FDA) | Allowed as a flavouring only when present as an incidental component of natural extracts; intentional addition is prohibited. |
| European Union (EFSA) | Listed as a flavouring substance with a technologically‑needed restriction; specific maximum levels are set for various food groups. |
| Australia & New Zealand (FSANZ) | Permitted as a flavouring at low concentrations, subject to safety assessment. |
| Canada (Health Canada) | Restricted; permitted only as a trace component of natural flavour extracts. |
| Pesticide regulation | Approved for use as an attractant in fruit‑fly monitoring traps under specific label instructions; not approved for broad‑scale pesticide applications. |
Environmental considerations
Methyl eugenol is readily volatilised and may contribute to the aroma profile of ecosystems where source plants are native. It exhibits low persistence in soil and water due to moderate biodegradability under aerobic conditions. No major bioaccumulation concerns have been documented.
References (selected)
- Food and Agriculture Organization (FAO) – Essential Oil Handbook (2020).
- U.S. Food and Drug Administration (FDA). “Flavoring Substances.” (2022).
- European Food Safety Authority (EFSA). “Scientific Opinion on the safety of methyl eugenol used as a flavouring.” (2018).
- International Programme on Chemical Safety (IPCS). Methyl Eugenol – Safety Data Sheet. (2021).
This summary reflects current encyclopedic knowledge of methyl eugenol as of the latest available literature.
