2,6,6-Trimethyl-1-cyclohexen-1-acetaldehyde (CAS 472-66-2) — Citrus Top to middle Note Fragrance Ingredient
2,6,6-Trimethyl-1-cyclohexen-1-acetaldehyde
CAS 472-66-2
What Is 2,6,6-Trimethyl-1-cyclohexen-1-acetaldehyde?
2,6,6-Trimethyl-1-cyclohexen-1-acetaldehyde is a synthetic fragrance ingredient used in perfumery to add fresh, floral, and citrusy notes. It is commonly found in fine fragrances, body care products, and household cleaners. This molecule contributes to the bright, uplifting character of many modern scents, often enhancing floral bouquets or adding a crisp edge to citrus compositions.
Safety Profile
USE WITH AWARENESSWhat Does 2,6,6-Trimethyl-1-cyclohexen-1-acetaldehyde Smell Like?
This aldehyde delivers a vibrant, fresh aroma with pronounced citrus and floral facets. The top note bursts with crisp lemon peel and bergamot zest, evolving into a heart of dewy rose petals and green stems. As it dries down, subtle woody undertones emerge, reminiscent of freshly sanded cedar. The overall effect is radiant and slightly metallic, like sunlight glinting off morning dew on a flower garden.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used here to amplify the citrusy freshness and add a modern floralcy that bridges the lemon top notes with the pink pepper and jasmine heart.
Provides the sparkling, slightly metallic freshness that makes this citrus-aquatic fragrance so distinctive and long-lasting.
2D Molecular Structure
SMILES: CC1=C(CC=O)C(C)(C)CCC1
Chemistry, Properties & Perfumer Guide
The Chemistry
2,6,6-Trimethyl-1-cyclohexen-1-acetaldehyde belongs to the cyclohexene derivative class of fragrance chemicals. It is synthesized through aldol condensation reactions starting from citral or related terpenoid precursors. The molecule features an α,β-unsaturated aldehyde group conjugated with a cyclohexene ring, which contributes to its reactivity and odor characteristics. The trimethyl substitution pattern enhances volatility and modifies the scent profile.
Physical & Chemical Properties
| Boiling Point | Approx. 220-230°C |
|---|---|
| Density | ~0.92 g/cm³ |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.5-2% | Up to 5% | Adds freshness and lift |
| Body Care | 0.1-0.5% | Up to 1% | Brightening effect |
Classic Accords
Tip: Use in citrus or floral compositions where a bright, slightly metallic freshness is desired.
Alternatives & Comparisons
Offers similar floral freshness but with more sweetness and less citrus character.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
No specific IFRA restrictions. General aldehyde precautions apply.
GHS Classification
RIFM Assessment
RIFM assessment ongoing. Preliminary data suggests safe use at current levels.
Sustainability
As a synthetic material, this ingredient doesn’t require agricultural land but does depend on petrochemical feedstocks. Modern synthesis routes aim to minimize waste and energy use. Its high potency means relatively small quantities are needed in formulations.
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References
- Bauer, K. et al. (2001). Common Fragrance and Flavor Materials. Wiley-VCH.
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorPhysicochemical Properties
DTXSID: DTXSID0047088
Physical Properties
| Molecular Weight | 166.264 g/mol🔬 EPA CompTox |
| Density | 0.879 g/cm^3🔬 EPA CTX |
| Boiling Point | 58.5 °C🔬 EPA CTX |
| Melting Point | 21.432 °C📊 OPERA |
| Flash Point | 84.13 °C📊 OPERA |
| Refractive Index | 1.45 Dimensionless📊 OPERA |
| Molar Volume | 189.029 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 3.285 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 3.285 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 3.285 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 5.86 Log10 unitless📊 OPERA |
| Water Solubility | 0.002 mol/L📊 OPERA |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0.178 mmHg📊 OPERA |
| Viscosity | 2.345 cP📊 OPERA |
| Surface Tension | 27.462 dyn/cm📊 OPERA |
| Thermal Conductivity | 118.153 mW/(m*K)📊 OPERA |
Molecular Descriptors
| Topological Polar Surface Area | 17.07 Ų💻 Computed |
| H-Bond Donors | 0 count💻 Computed |
| H-Bond Acceptors | 1 count💻 Computed |
| Rotatable Bonds | 2 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 50.809 cm^3/mol📊 OPERA |
| Polarizability | 20.142 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.
