γ-Nonalactone, also written as γ‑Nonalactone or gamma‑nonalactone, is a cyclic ester (lactone) belonging to the class of γ‑lactones. Its systematic IUPAC name is 5‑nonyl‑2‑(5H)‑furanone. The compound has the molecular formula C₉H₁₄O₂ and a molecular weight of 154.20 g·mol⁻¹.
Chemical Structure
γ‑Nonalactone consists of a five‑membered lactone ring (a γ‑lactone) bearing a straight‑chain alkyl substituent that extends the total carbon count to nine. The structure can be represented by the SMILES notation CCCCCCCC1OC(=O)C1.
Physical Properties
- State at room temperature: Colorless liquid
- Density: Approximately 1.04 g·cm⁻³ (reported at 20 °C)
- Boiling point: Reported values range from 260 °C to 270 °C under atmospheric pressure
- Solubility: Miscible with many organic solvents (e.g., ethanol, diethyl ether); limited solubility in water
Sensory Characteristics
γ‑Nonalactone possesses a characteristic coconut‑like aroma and is described as having sweet, creamy, and fruity notes. These sensory properties make it an important ingredient in flavor and fragrance formulations.
Occurrence and Production
- Natural occurrence: γ‑Nonalactone has been identified in a variety of natural sources, including certain fruits (e.g., apricots, peaches), dairy products, and coconut extracts.
- Industrial synthesis: The compound is commonly produced by the oxidative cyclization of the corresponding hydroxy‑acid precursor or by hydrogenation of related unsaturated lactones. Commercial production is oriented toward the flavor and fragrance industry.
Applications
| Sector | Use |
|---|---|
| Flavor industry | Employed as a flavoring agent to impart coconut, creamy, and fruity notes in foods such as baked goods, desserts, dairy products, and beverages. |
| Fragrance industry | Utilized in perfumery for its sweet, tropical aroma, often in compositions evoking coconut or tropical themes. |
| Research | Serves as a model compound in studies of lactone metabolism and aroma perception. |
Safety and Regulatory Status
γ‑Nonalactone is generally recognized as safe (GRAS) for use as a flavoring substance by food safety authorities such as the U.S. Food and Drug Administration (FDA). Toxicological data indicate low acute toxicity, but standard occupational exposure limits and handling precautions (e.g., use of gloves and adequate ventilation) are recommended for industrial settings.
Related Compounds
γ‑Nonalactone belongs to a broader family of γ‑lactones that includes γ‑octalactone, γ‑nonalactone, and γ‑decalactone, each differing by the length of the alkyl side chain and associated odor profiles.
References
- Flavor and Extract Manufacturers Association (FEMA) GRAS list, entry for gamma‑nonalactone.
- U.S. Food and Drug Administration (FDA), “Food Additive Status List.”
- “Lactones: Chemistry, Synthesis, and Applications”, CRC Press, 2015.
- PubChem Compound Summary for CID 12414 (γ‑Nonalactone), National Center for Biotechnology Information.
Note: All data presented are derived from established chemical and regulatory sources. When specific physical property values vary across sources, ranges are reported to reflect the available literature.