Methyl cyclohexadiene (mixture of isomers) (CAS 30640-46-1) — Green Top to middle Note Fragrance Ingredient
Methyl cyclohexadiene (mixture of isomers)
CAS 30640-46-1
What Is Methyl cyclohexadiene (mixture of isomers)?
Methyl cyclohexadiene is a synthetic fragrance ingredient used to create fresh, green, and slightly woody scent effects in perfumes and household products. You’ll encounter it in air fresheners, fabric softeners, and some modern colognes where a crisp, outdoorsy quality is desired. This molecule matters because it helps perfumers build naturalistic green notes without relying on plant extracts, offering consistency and sustainability benefits over natural alternatives.
Safety Profile
GENERALLY SAFEWhat Does Methyl cyclohexadiene (mixture of isomers) Smell Like?
Methyl cyclohexadiene delivers a vibrant, sappy green character reminiscent of crushed stems and freshly cut foliage. The initial burst carries sharp, almost citrus-like terpenic edges that quickly soften into a rounded, slightly earthy woodiness. As it evolves, there’s a subtle gasoline-like nuance that adds modern edge, making it useful for creating contemporary interpretations of classic green accords. The dry-down reveals a faintly resinous quality, though the overall effect remains bright and diffusive rather than heavy or tenacious.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used in modern reformulations to rebuild the legendary galbanum note, providing the sharp green bite that makes this fragrance emblematic of spring foliage.
Helps construct the dewy violet leaf effect, blending with ionones to create that crisp, aristocratic greenery central to the composition.
2D Molecular Structure
SMILES: CC1=CC=CCC1
Chemistry, Properties & Perfumer Guide
The Chemistry
Methyl cyclohexadiene exists as a mixture of 1-methyl-1,3-cyclohexadiene and 1-methyl-1,4-cyclohexadiene isomers, both C7H10 hydrocarbons. These conjugated dienes are typically synthesized through catalytic dehydrogenation of methylcyclohexane or dehydration of methylcyclohexanol. The isomers exhibit different reactivity patterns in perfumery applications due to variations in double bond positioning, with the 1,3-isomer being more reactive in Diels-Alder reactions. Neither isomer is known to occur naturally in significant quantities, making this exclusively a synthetic material in fragrance applications.
Physical & Chemical Properties
| Appearance | Colorless to pale yellow liquid |
|---|---|
| Boiling Point | 110-115 °C (mixture) |
| Density | 0.83-0.85 g/cm³ |
| Refractive Index | 1.46-1.47 (20°C) |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.5-2% | Up to 5% | For green accent notes |
| Functional Products | 0.1-0.5% | Up to 1% | In air care formulations |
Classic Accords
Tip: Stabilize with antioxidants to prevent polymerization during storage.
Alternatives & Comparisons
When a more intense, longer-lasting green effect is needed, though lacks the subtle gasoline nuance of methyl cyclohexadiene.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
Not currently restricted under IFRA standards.
GHS Classification
RIFM Assessment
RIFM has reviewed available data and found no significant safety concerns at current usage levels.
Sustainability
As a purely synthetic material, methyl cyclohexadiene avoids agricultural supply chain issues. Production typically uses petroleum-derived feedstocks, though some manufacturers are exploring bio-based routes via terpene chemistry. Its high odor potency means small quantities deliver effect, reducing environmental load compared to some natural alternatives.
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References
- Arctander, S. (1969). Perfume and Flavor Chemicals. Montclair, NJ.
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorIngredient Data Sheet
CAS 30640-46-1Physical Properties
| Molecular Weight | 94.15 g/mol🔬 PubChem |
| LogP (Octanol-Water) | 2.1🔬 PubChem |
| Boiling Point | 118 °C🔬 EPA CompTox |
| log Kp (skin permeability) | -1.783💻 Calculated |
| SMILES | CC1=CC=CCC1🔬 PubChem |
Volatility & Performance
| Fragrance Note | Top💻 Calculated |
Odor & Flavor
| Primary Descriptors | greenwoody• leffingwell |
| Functional Groups | alkene💻 RDKit |
Physical data: PubChem (NIH/NLM), U.S. EPA CompTox Dashboard, EPA OPERA models, RDKit. Odor & flavor: Arctander (Perfume & Flavor Chemicals), Fenaroli's Handbook of Flavor Ingredients, Leffingwell. Thresholds: van Gemert (Compilations of Odour Threshold Values). Regulatory: IFRA Standards 51st, FEMA GRAS. Trade names: Surburg (Common Fragrance & Flavor Materials). All data compiled and cross-referenced for perfumertools.com.
Physicochemical Properties
DTXSID: DTXSID1051985
Physical Properties
| Molecular Weight | 94.15 g/mol🔬 PubChem |
| Density | 0.846 g/cm^3🔬 PubChem |
| Boiling Point | 119 °C🔬 PubChem |
| Flash Point | 68 °C📊 PubChem |
Partition & Solubility
| LogP (Octanol-Water) | 2.1 Log10 unitless🔬 PubChem |
Transport Properties
| Vapor Pressure | 26.07 mmHg📊 PubChem |
Molecular Descriptors
| Topological Polar Surface Area | 0 Ų💻 Computed |
| H-Bond Donors | 0 count💻 Computed |
| H-Bond Acceptors | 0 count💻 Computed |
| Molar Refractivity | 32.13 cm^3/mol💻 Computed |
Data Sources:
🔬 EPA Experimental data from U.S. EPA CompTox Chemicals Dashboard & CTX APIs. 📊 OPERA Predicted using EPA's OPERA QSAR models. 💻 Computed Calculated from SMILES using RDKit.
