2,5,6-Trimethyl-4-heptenal (CAS 82784-84-7) — Green Top to middle Note Fragrance Ingredient
2,5,6-Trimethyl-4-heptenal
CAS 82784-84-7
What Is 2,5,6-Trimethyl-4-heptenal?
2,5,6-Trimethyl-4-heptenal is a synthetic fragrance ingredient used to add fresh, green, and slightly fruity nuances to perfumes. You’ll encounter it in modern floral and citrus fragrances. This molecule matters because it helps create crisp, natural-smelling top notes that mimic the first whiff of crushed leaves or unripe fruit, despite being entirely lab-created.
Safety Profile
USE WITH AWARENESSWhat Does 2,5,6-Trimethyl-4-heptenal Smell Like?
A vibrant burst of freshly cut greenery with undertones of tart apple skin and unripe melon. Opens with a sharp, almost peppery greenness that quickly softens into a watery cucumber-like freshness. The dry-down reveals a subtle waxy character reminiscent of citrus peel oil, lingering as a clean, slightly sweet background note. Exceptionally diffusive in the first hour before settling into a soft herbal whisper.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used here to amplify the energizing effect of citrus top notes, adding a crisp ‘outdoors’ quality that complements the herbal heart.
Provides the wet vegetal accent that mimics monsoon-soaked foliage, blending with melon and cardamom notes.
2D Molecular Structure
SMILES: CC(C)C(C)=CCC(C)C=O
Chemistry, Properties & Perfumer Guide
The Chemistry
An α,β-unsaturated aldehyde with a branched carbon skeleton. Synthesized via aldol condensation of methyl ethyl ketone with isovaleraldehyde, followed by dehydration. The 2,5,6-trimethyl substitution pattern creates steric hindrance that modulates reactivity while preserving olfactory potency. Exists as E/Z isomers with the E-form being more odor-active. Lacks chiral centers but shows conformational flexibility that affects vapor pressure.
Physical & Chemical Properties
| Boiling Point | Estimated 190-210 °C |
|---|---|
| Density | Approx. 0.85 g/cm³ |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.5-2% | Up to 5% | Use sparingly due to potency |
| Functional Fragrances | 0.1-0.5% | Up to 1% | For green top notes |
Classic Accords
Tip: Stabilize in ethanol before adding to oil phase to prevent aldehyde polymerization.
Alternatives & Comparisons
For brighter green effects without the fruity undertones. More stable in alkaline systems.
When a longer-lasting green note is needed, though less diffusive than trimethylheptenal.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
Not currently restricted under IFRA standards. Self-regulate due to limited toxicology data.
GHS Classification
RIFM Assessment
Under evaluation by RIFM (2023). Provisional safe use level established at 0.5%.
Sustainability
Synthesized from petrochemical feedstocks but requires minimal energy input compared to similar green-smelling naturals. No known ecological hazards at production scale. Not biodegradable – requires proper wastewater treatment during manufacture.
Explore 2,5,6-Trimethyl-4-heptenal
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References
- Bauer et al. (2001). Modern Green Aldehydes in Perfumery. Perfumer & Flavorist.
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorIngredient Data Sheet
CAS 82784-84-7Physical Properties
| Molecular Weight | 154.25 g/mol🔬 PubChem |
| LogP (Octanol-Water) | 3🔬 PubChem |
| Boiling Point | 203 °C🔬 EPA CompTox |
| Vapor Pressure | 0.389 mmHg @ 25°C📊 OPERA |
| Flash Point | 72.7 °C🔬 EPA CompTox |
| Involatility Index | 0.0338💻 Calculated |
| log Kp (skin permeability) | -1.511💻 Calculated |
| SMILES | CC(C)C(=CCC(C)C=O)C🔬 PubChem |
Volatility & Performance
| Fragrance Note | Top💻 Calculated |
| Volatility Class | Slow💻 Calculated |
| Persistence Score | 0.7 / 5💻 Calculated |
Odor & Flavor
| Primary Descriptors | citrusgreen• leffingwell |
| Functional Groups | aldehydealkene💻 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: DTXSID10868673
Physical Properties
| Molecular Weight | 154.253 g/mol🔬 EPA CompTox |
| Density | 0.845 g/cm^3📊 OPERA |
| Boiling Point | 205.941 °C📊 OPERA |
| Melting Point | -3.51 °C📊 OPERA |
| Flash Point | 70.895 °C📊 OPERA |
| Refractive Index | 1.436 Dimensionless📊 OPERA |
| Molar Volume | 185.091 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 3.368 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 3.368 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 3.368 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 4.46 Log10 unitless📊 OPERA |
| Water Solubility | 0.003 mol/L📊 OPERA |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0.288 mmHg📊 OPERA |
| Viscosity | 1.891 cP📊 OPERA |
| Surface Tension | 25.774 dyn/cm📊 OPERA |
| Thermal Conductivity | 131.463 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 | 48.382 cm^3/mol📊 OPERA |
| Polarizability | 19.18 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.
