2-Methyl-1,3-cyclohexadiene (CAS 1489-57-2) — Green Top to middle Note Fragrance Ingredient
2-Methyl-1,3-cyclohexadiene
CAS 1489-57-2
What Is 2-Methyl-1,3-cyclohexadiene?
2-Methyl-1,3-cyclohexadiene is a synthetic organic compound used in perfumery to add fresh, green, and slightly woody nuances. It’s primarily found in modern fragrance compositions where its unique chemical structure contributes to complex scent profiles. This ingredient matters because it helps perfumers create innovative accords that bridge traditional woody notes with contemporary freshness, offering a versatile tool for scent design.
Safety Profile
USE WITH AWARENESSWhat Does 2-Methyl-1,3-cyclohexadiene Smell Like?
2-Methyl-1,3-cyclohexadiene presents a crisp, green opening with subtle terpenic undertones reminiscent of crushed leaves. As it evolves, the scent reveals a dry, woody heart with faint citrusy highlights. The dry-down is clean and slightly resinous, leaving a transparent woody impression that blends well with other materials. Its character sits between fresh pine needles and the dry aspect of cedarwood, making it particularly useful for modern fougère and chypre compositions.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used as a fresh-woody bridge between citrus top notes and amber base, contributing modern transparency to this contemporary woody fragrance.
Provides the sharp green opening that gradually softens into the fragrance’s woody heart, creating a dynamic scent evolution.
2D Molecular Structure
SMILES: CC1=CCCC=C1
Chemistry, Properties & Perfumer Guide
The Chemistry
2-Methyl-1,3-cyclohexadiene belongs to the class of cyclic dienes, specifically a substituted cyclohexadiene. It’s typically synthesized through Diels-Alder reactions or dehydrogenation of methylcyclohexane derivatives. The molecule’s conjugated double bond system contributes to its reactivity and odor characteristics. While not found in nature, its structure is reminiscent of terpenoid degradation products that occur in some essential oils.
Physical & Chemical Properties
| Appearance | Colorless to pale yellow liquid |
|---|---|
| Boiling Point | Approx. 150-160 °C (estimated) |
| Density | Approx. 0.85-0.90 g/cm³ |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.5-2% | Up to 5% | Used as modifier in woody accords |
| Functional Fragrance | 0.1-1% | Up to 2% | Adds freshness to cleaning products |
Classic Accords
Tip: Use in small quantities to add lift to heavy woody bases without overpowering the composition.
Alternatives & Comparisons
For a more citrus-oriented terpene character with similar volatility but different odor profile.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
Not currently restricted by IFRA. No specific usage limits established.
RIFM Assessment
No formal RIFM assessment available. Recommended to follow general terpene safety guidelines.
Sustainability
As a synthetic material, 2-Methyl-1,3-cyclohexadiene offers consistent quality without natural sourcing constraints. Production typically uses petrochemical feedstocks, though potential exists for bio-based synthesis routes. Its efficient use in formulations (low dosage required) contributes to reduced environmental impact compared to some natural alternatives.
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References
- Chemical Abstracts Service (2023). Substance Details for CAS 1489-57-2. CAS Registry
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorPhysicochemical Properties
DTXSID: DTXSID7061726
Physical Properties
| Molecular Weight | 94.157 g/mol🔬 EPA CompTox |
| Density | 0.858 g/cm^3📊 OPERA |
| Boiling Point | 107.5 °C🔬 EPA CTX |
| Melting Point | -27.965 °C📊 OPERA |
| Flash Point | 9.253 °C📊 OPERA |
| Refractive Index | 1.481 Dimensionless📊 OPERA |
| Molar Volume | 111.026 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 2.944 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 2.944 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 2.944 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 4.02 Log10 unitless📊 OPERA |
| Water Solubility | 0.002 mol/L📊 OPERA |
| Henry's Law Constant | 0.024 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 29.514 mmHg📊 OPERA |
| Viscosity | 0.489 cP📊 OPERA |
| Surface Tension | 24.837 dyn/cm📊 OPERA |
| Thermal Conductivity | 129.96 mW/(m*K)📊 OPERA |
Molecular Descriptors
| Topological Polar Surface Area | 0 Ų💻 Computed |
| H-Bond Donors | 0 count💻 Computed |
| H-Bond Acceptors | 0 count💻 Computed |
| Rotatable Bonds | 0 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 31.582 cm^3/mol📊 OPERA |
| Polarizability | 12.52 Å^3📊 OPERA |
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.
