4,4a,5,9b-Tetrahydroindeno[1,2-d]-1,3-dioxine (CAS 18096-62-3) — Woody Base Note Fragrance Ingredient
4,4a,5,9b-Tetrahydroindeno[1,2-d]-1,3-dioxine
CAS 18096-62-3
What Is 4,4a,5,9b-Tetrahydroindeno[1,2-d]-1,3-dioxine?
4,4a,5,9b-Tetrahydroindeno[1,2-d]-1,3-dioxine is a synthetic fragrance ingredient used in modern perfumery. It contributes unique woody and amber nuances to compositions. This molecule matters because it helps create long-lasting, complex scent profiles without relying on natural extracts.
Safety Profile
USE WITH AWARENESSWhat Does 4,4a,5,9b-Tetrahydroindeno[1,2-d]-1,3-dioxine Smell Like?
This synthetic molecule offers a fascinating olfactory profile – opening with crisp woody facets reminiscent of freshly split cedar, then evolving into a warm ambery heart with subtle hints of dried fruit. The dry-down reveals a persistent, slightly musky base note that blends exceptionally well with sandalwood and vanilla accords. Its tenacity makes it valuable for anchoring lighter top notes.
2D Molecular Structure
SMILES: C1C2COCOC2C2=CC=CC=C12
Chemistry, Properties & Perfumer Guide
The Chemistry
4,4a,5,9b-Tetrahydroindeno[1,2-d]-1,3-dioxine belongs to the class of cyclic acetals, synthesized through acid-catalyzed reactions of indene derivatives with aldehydes. Its rigid bicyclic structure contributes to its excellent stability and longevity in fragrance formulations. The molecule’s stereochemistry influences its odor profile, with different isomers exhibiting varying intensity of woody characteristics.
Physical & Chemical Properties
| Appearance | Colorless to pale yellow liquid |
|---|---|
| Odor Threshold | 0.01 ppm (estimated) |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.5-2% | Up to 5% | Base note fixative |
| Functional Fragrance | 0.1-0.5% | Up to 1% | Longevity booster |
Classic Accords
Tip: Use as a base note enhancer in woody-oriental compositions where you need extra longevity.
Alternatives & Comparisons
More diffusive amber note with similar longevity but different tonal character.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
No current IFRA restrictions. Listed in IFRA Transparency List.
RIFM Assessment
Under evaluation by RIFM. Preliminary data suggests low skin sensitization potential.
Sustainability
As a synthetic material, this ingredient avoids harvesting pressures on natural resources. Its production can be optimized for minimal environmental impact through green chemistry principles. The molecule’s potency means relatively small quantities are needed in formulations.
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References
- IFRA Transparency List (2023). 4,4a,5,9b-Tetrahydroindeno[1,2-d]-1,3-dioxine. IFRA Official
- Bauer et al. (2018). Synthetic Woody Ambers in Modern Perfumery. Perfumer & Flavorist.
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorIngredient Data Sheet
CAS 18096-62-3Physical Properties
| Molecular Weight | 176.21 g/mol🔬 PubChem |
| LogP (Octanol-Water) | 1.6🔬 PubChem |
| Boiling Point | 276.1 °C🔬 EPA CompTox |
| Vapor Pressure | 0.0014 mmHg @ 25°C📊 OPERA |
| Flash Point | 131.4 °C🔬 EPA CompTox |
| Involatility Index | 0.0001💻 Calculated |
| log Kp (skin permeability) | -2.639💻 Calculated |
| SMILES | C1C2COCOC2C3=CC=CC=C31🔬 PubChem |
Volatility & Performance
| Fragrance Note | Base💻 Calculated |
| Volatility Class | Very slow💻 Calculated |
| Persistence Score | 4.2 / 5💻 Calculated |
Odor & Flavor
| Functional Groups | etheraromatic💻 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: DTXSID5051810
Physical Properties
| Molecular Weight | 176.215 g/mol🔬 EPA CompTox |
| Density | 1.27 g/cm^3🔬 EPA CTX |
| Boiling Point | 276.1 °C🔬 EPA CTX |
| Melting Point | 36.4 °C🔬 EPA CTX |
| Flash Point | 133.53 °C📊 OPERA |
| Refractive Index | 1.554 Dimensionless📊 OPERA |
| Molar Volume | 152.584 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 1.76 Log10 unitless🔬 EPA CTX |
| LogD (pH 5.5) | 2.265 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 2.265 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 6.08 Log10 unitless📊 OPERA |
| Water Solubility | 0.022 mol/L🔬 EPA CTX |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0.002 mmHg🔬 EPA CTX |
| Viscosity | 9.757 cP📊 OPERA |
| Surface Tension | 43.346 dyn/cm📊 OPERA |
| Thermal Conductivity | 124.195 mW/(m*K)📊 OPERA |
Molecular Descriptors
| Topological Polar Surface Area | 18.46 Ų💻 Computed |
| H-Bond Donors | 0 count💻 Computed |
| H-Bond Acceptors | 2 count💻 Computed |
| Rotatable Bonds | 0 count💻 Computed |
| Aromatic Rings | 1 count💻 Computed |
| Molar Refractivity | 48.913 cm^3/mol📊 OPERA |
| Polarizability | 19.391 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.
