3-Cyclopentene-1-butanal, alpha,2,2,3-tetramethyl-.gamma.-methylene (CAS 166432-53-7) — Woody Base Note Fragrance Ingredient
3-Cyclopentene-1-butanal, alpha,2,2,3-tetramethyl-.gamma.-methylene
CAS 166432-53-7
What Is 3-Cyclopentene-1-butanal, alpha,2,2,3-tetramethyl-.gamma.-methylene?
3-Cyclopentene-1-butanal, alpha,2,2,3-tetramethyl-.gamma.-methylene is a synthetic fragrance ingredient used in fine fragrances and personal care products. It adds woody, amber-like nuances to compositions. Consumers encounter this ingredient in premium perfumes where it contributes to sophisticated dry-down accords. This molecule matters because it offers perfumers a unique balance between woody and balsamic characteristics, enabling creative flexibility in modern fragrance design.
Safety Profile
USE WITH AWARENESSWhat Does 3-Cyclopentene-1-butanal, alpha,2,2,3-tetramethyl-.gamma.-methylene Smell Like?
This synthetic molecule opens with a surprising burst of woody-green freshness, like the first snap of a young pine branch. Within minutes, it evolves into a warm ambered heart reminiscent of sun-baked cedar planks. The dry-down reveals a sophisticated balsamic depth, with subtle hints of dried fruit peel and a whisper of leathery musk. Its behavior on skin is remarkably persistent, unfolding gradually over hours rather than disappearing abruptly.
2D Molecular Structure
SMILES: CC(CC(=C)C1CC=C(C)C1(C)C)C=O
Chemistry, Properties & Perfumer Guide
The Chemistry
3-Cyclopentene-1-butanal belongs to the family of modified terpenoids, specifically a cyclopentene derivative with aldehyde functionality. Its synthesis typically involves Diels-Alder reactions followed by careful oxidation steps. The tetramethyl substitution pattern creates significant steric hindrance, influencing both its odor characteristics and chemical reactivity. While not found in nature, its structural motifs echo those found in degraded sesquiterpenoids.
Physical & Chemical Properties
| Boiling Point | Not available |
|---|---|
| Density | Not available |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.5-2% | Up to 5% | Provides woody-amber foundation |
| Personal Care | 0.1-0.5% | Up to 1% | Used for subtle dry-down effects |
Classic Accords
Tip: Combine with ionones to enhance woody character without overpowering floral heart notes.
Alternatives & Comparisons
When seeking more pronounced woody-dry effects with less balsamic sweetness.
For cleaner ambery effects with superior diffusion and less coloration issues.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
Not currently restricted under IFRA standards. Monitoring recommended due to structural alerts.
EU Allergen Declaration
Not listed in EU allergen regulation (EC) No 1223/2009 Annex III.
GHS Classification
RIFM Assessment
Under evaluation by RIFM. Preliminary data suggests moderate skin sensitization potential.
Sustainability
As a fully synthetic material, this ingredient avoids natural resource depletion concerns. However, its synthesis requires petrochemical feedstocks and energy-intensive processes. Future green chemistry approaches may improve its environmental profile through catalytic methods and renewable raw materials.
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References
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorPhysicochemical Properties
DTXSID: DTXSID60888760
Physical Properties
| Molecular Weight | 206.329 g/mol🔬 EPA CompTox |
| Density | 0.881 g/cm^3📊 OPERA |
| Boiling Point | 263.24 °C📊 OPERA |
| Melting Point | 12.401 °C📊 OPERA |
| Flash Point | 113.68 °C📊 OPERA |
| Refractive Index | 1.467 Dimensionless📊 OPERA |
| Molar Volume | 231.155 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 4.317 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 4.317 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 4.317 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 6.33 Log10 unitless📊 OPERA |
| Water Solubility | 0.001 mol/L📊 OPERA |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0.019 mmHg📊 OPERA |
| Viscosity | 1.494 cP📊 OPERA |
| Surface Tension | 27.889 dyn/cm📊 OPERA |
| Thermal Conductivity | 122.031 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 | 4 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 64.109 cm^3/mol📊 OPERA |
| Polarizability | 25.415 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.
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