Butyl 2-methylcrotonate (E) (CAS 7785-66-2) — Green Top Note Fragrance Ingredient
Butyl 2-methylcrotonate (E)
CAS 7785-66-2
What Is Butyl 2-methylcrotonate (E)?
Butyl 2-methylcrotonate is a synthetic ester used in perfumery for its fruity, apple-like scent. It’s commonly found in artificial fruit flavors and fragrances. This ingredient matters because it provides a crisp, fresh top note that enhances fruity and green fragrance compositions.
Safety Profile
GENERALLY SAFEWhat Does Butyl 2-methylcrotonate (E) Smell Like?
Butyl 2-methylcrotonate delivers an immediate burst of crisp, green apple with a slightly tart edge. The initial sharpness mellows into a juicy, fruity heart reminiscent of underripe pears. Over time, it settles into a faintly sweet, slightly woody base. The dry-down is subtle but persistent, leaving a clean, almost shampoo-like freshness.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used to create the crisp, artificial apple top note that defines this modern fruity fragrance.
2D Molecular Structure
SMILES: CCCCOC(=O)C(\C)=C\C
Chemistry, Properties & Perfumer Guide
The Chemistry
Butyl 2-methylcrotonate is an ester derived from 2-methylcrotonic acid and butanol. It is synthesized through esterification reactions, often catalyzed by acids. The molecule features a crotonate backbone with a methyl group at the 2-position, contributing to its fruity odor profile.
Physical & Chemical Properties
| Boiling Point | N/A |
|---|---|
| Density | N/A |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 1-3% | Up to 5% | Adds fruity freshness |
| Functional Fragrance | 0.5-2% | Up to 3% | Used in shampoos and soaps |
Classic Accords
Tip: Use sparingly to avoid overwhelming the composition with synthetic fruitiness.
Alternatives & Comparisons
Offers a similar fruity profile with slightly more floral character.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
No IFRA restrictions apply.
EU Allergen Declaration
Not listed as an EU allergen.
RIFM Assessment
No specific RIFM assessment found.
Sustainability
As a synthetic ingredient, Butyl 2-methylcrotonate is produced from petrochemical feedstocks. Its environmental impact depends on manufacturing processes and waste management.
Explore Butyl 2-methylcrotonate (E)
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References
- PubChem Compound Summary for Butyl 2-methylcrotonate PubChem
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorIngredient Data Sheet
CAS 7785-66-2Physical Properties
| Molecular Weight | 156.22 g/mol🔬 PubChem |
| LogP (Octanol-Water) | 3.1🔬 PubChem |
| Boiling Point | 195 °C🔬 EPA CompTox |
| Vapor Pressure | 1.6596 mmHg @ 25°C📊 OPERA |
| Flash Point | 72.2 °C🔬 EPA CompTox |
| Involatility Index | 0.1431💻 Calculated |
| log Kp (skin permeability) | -1.452💻 Calculated |
| SMILES | CCCCOC(=O)C(=CC)C🔬 PubChem |
Volatility & Performance
| Fragrance Note | Top💻 Calculated |
| Volatility Class | Moderate💻 Calculated |
| Persistence Score | 0.5 / 5💻 Calculated |
Odor & Flavor
| Primary Descriptors | carameletherealfloralfruityherbalsweet• leffingwell |
| Functional Groups | esteretheralkene💻 RDKit |
| “This ester was developed for use in artificial essential oils, when Tiglic and Angelic acids became commercially available. However, the higher esters have become more popular with their softer, less gassy odor and superior tenacity. Since the title ester has not been identified in Roman Chamomile oil, it is”📖 Arctander | |
Sensory Thresholds
| Odor Detection Threshold | 0.0042 ppm📖 van Gemert |
Regulatory Status
| GRAS Status | Generally Recognized as Safe⚖️ FEMA GRAS |
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: DTXSID7052527
Physical Properties
| Molecular Weight | 156.225 g/mol🔬 EPA CompTox |
| Density | 0.906 g/cm^3📊 OPERA |
| Boiling Point | 193.458 °C📊 OPERA |
| Melting Point | -27.643 °C📊 OPERA |
| Flash Point | 72.752 °C📊 OPERA |
| Refractive Index | 1.435 Dimensionless📊 OPERA |
| Molar Volume | 173.994 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 2.951 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 2.951 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 2.951 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 4.43 Log10 unitless📊 OPERA |
| Water Solubility | 0.019 mol/L📊 OPERA |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0.755 mmHg📊 OPERA |
| Surface Tension | 27.232 dyn/cm📊 OPERA |
Molecular Descriptors
| Topological Polar Surface Area | 26.3 Ų💻 Computed |
| H-Bond Donors | 0 count💻 Computed |
| H-Bond Acceptors | 2 count💻 Computed |
| Rotatable Bonds | 4 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 45.42 cm^3/mol📊 OPERA |
| Polarizability | 18.006 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.
