Dihydronootkatone (CAS 20489-53-6) — Citrus Top to Middle Note Fragrance Ingredient
Dihydronootkatone
CAS 20489-53-6
What Is Dihydronootkatone?
Dihydronootkatone is a synthetic fragrance ingredient prized for its grapefruit-like citrus character with woody undertones. It’s commonly found in citrus-forward perfumes, body care products, and sometimes used as a flavoring agent. This molecule matters because it provides long-lasting citrus effects without the volatility of natural citrus oils, making fragrances more durable while avoiding phototoxicity concerns.
Safety Profile
GENERALLY SAFEWhat Does Dihydronootkatone Smell Like?
Dihydronootkatone bursts with an intense, sparkling grapefruit peel aroma – think ruby red grapefruit zest crushed between fingers with a hint of bitter pith. The initial citrus sharpness mellows into a smooth, woody-citrus heart reminiscent of freshly peeled grapefruit segments. Unlike fleeting natural citrus oils, it lingers with a dry, cedary base note that adds sophistication to citrus accords. When diluted, it reveals subtle floral nuances akin to bergamot tea leaves steeping in warm water.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used as the citrus backbone that persists beyond the opening, blending with lemon and bergamot to create an enduring cologne structure.
Provides the tart grapefruit illusion in the top notes while anchoring the citrus to prevent rapid evaporation.
2D Molecular Structure
SMILES: C[C@@H]1CC(=O)C[C@@H]2CC[C@H](C[C@@]12C)C(C)=C
Chemistry, Properties & Perfumer Guide
The Chemistry
Dihydronootkatone belongs to the sesquiterpenoid ketone class, structurally related to nootkatone from grapefruit but with increased stability. Industrially produced through hydrogenation of nootkatone or total synthesis from valencene. The saturated structure eliminates photoinstability concerns while preserving the characteristic citrus-woody odor profile. Exists as enantiomers with slightly different olfactory properties – the (4R) isomer being more citrus-dominant.
Physical & Chemical Properties
| Boiling Point | ~300 °C (estimated) |
|---|---|
| Density | ~0.95 g/cm³ (estimated) |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.5-2% | Up to 5% | Citrus accord stabilizer |
| Functional Fragrance | 0.1-0.5% | Up to 1% | Cleaning product freshnes |
Classic Accords
Tip: Use at 0.2-0.5% in citrus tops to extend freshness without overpowering delicate notes.
Alternatives & Comparisons
The natural precursor with brighter citrus but poorer stability. Use when photodegradation isn’t a concern.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
No IFRA restrictions. Listed in IFRA Transparency List.
RIFM Assessment
Considered safe for current fragrance use levels based on RIFM evaluation.
Sustainability
Synthetic production avoids agricultural land use and seasonal variability of natural citrus sources. Typically manufactured from valencene (from oranges) through catalytic processes. Carbon footprint depends on hydrogenation efficiency. Not known to bioaccumulate.
Explore Dihydronootkatone
Browse essential oils and aroma compounds.
Browse on iHerb →Affiliate disclosure: we may earn a small commission at no extra cost to you.
References
- Bauer 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: DTXSID30174460
Physical Properties
| Molecular Weight | 220.356 g/mol🔬 EPA CompTox |
| Density | 0.982 g/cm^3🔬 EPA CTX |
| Boiling Point | 292.248 °C📊 OPERA |
| Melting Point | 15.917 °C📊 OPERA |
| Flash Point | 128.693 °C📊 OPERA |
| Refractive Index | 1.482 Dimensionless📊 OPERA |
| Molar Volume | 235.198 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 4.281 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 4.281 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 4.281 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 7.33 Log10 unitless📊 OPERA |
| Water Solubility | 0 mol/L📊 OPERA |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0.002 mmHg📊 OPERA |
| Viscosity | 4.104 cP📊 OPERA |
| Surface Tension | 31.812 dyn/cm📊 OPERA |
| Thermal Conductivity | 125.996 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 | 1 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 66.994 cm^3/mol📊 OPERA |
| Polarizability | 26.558 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.
