2-Methylbutyraldehyde (CAS 96-17-3) — Green Top Note Fragrance Ingredient
2-Methylbutyraldehyde
CAS 96-17-3
What Is 2-Methylbutyraldehyde?
2-Methylbutyraldehyde is a synthetic fragrance ingredient with a powerful, fruity-green odor reminiscent of unripe apples or fresh-cut grass. You’ll encounter it in fruity perfumes, some food flavorings, and household products like air fresheners. This molecule matters because it adds a crisp, natural-seeming greenness to fragrances, helping create the illusion of just-picked fruits or dewy foliage even in entirely synthetic compositions.
Safety Profile
USE WITH AWARENESSWhat Does 2-Methylbutyraldehyde Smell Like?
2-Methylbutyraldehyde bursts with an intensely green, almost harsh top note – picture the acrid snap of breaking a green apple stem or the sappy bitterness of freshly torn leaves. This sharpness quickly mellows into a fruity heart resembling underripe bananas and kiwi skins, with a subtle nutty undertone. The dry-down is surprisingly warm, leaving faint caramelized sugar and almond impressions that balance its initial vegetal punch. In dilution, it becomes astonishingly fresh – like rain on hot pavement mingled with the tartness of green mango.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used here to amplify the razor-sharp green top notes, contributing to the fragrance’s iconic ‘just-mowed lawn’ freshness that contrasts beautifully with its violet leaf and sandalwood base.
This classic green floral employs 2-methylbutyraldehyde to enhance its galbanum accord, creating the illusion of crushed stems and dewy chlorophyll that defined mid-century green perfumery.
2D Molecular Structure
SMILES: CCC(C)C=O
Chemistry, Properties & Perfumer Guide
The Chemistry
2-Methylbutyraldehyde is a branched-chain aldehyde (C5H10O) belonging to the same chemical family as more common fragrance aldehydes like hexanal. While it occurs naturally in some fruits and vegetables, commercial production typically involves the oxidation of 2-methylbutanol or hydroformylation of butenes. Its reactivity makes it valuable for creating fruity heterocyclic compounds through aldol condensations. The molecule’s stereochemistry impacts its odor profile – the (R)-enantiomer tends to smell more intensely of green apples while the (S)-form has nuttier characteristics.
Physical & Chemical Properties
| Boiling Point | 92-94 °C |
|---|---|
| Density | 0.81 g/cm³ |
| Flash Point | 4 °C |
| Refractive Index | 1.389 |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.1-0.5% | Up to 1% | For green-fruity top notes |
| Functional Fragrance | 0.01-0.1% | Up to 0.3% | In air fresheners and cleaners |
Classic Accords
Tip: Always pre-dilute to 1-10% in ethanol or DPG to control its aggressive top notes and prevent formulation instability.
Alternatives & Comparisons
For a less aggressive, more universally pleasant green note – lacks the fruity-nutty complexity but is easier to work with at higher doses.
When an extreme green leaf effect is desired – even more potent but highly unstable, requiring careful stabilization in final products.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
No IFRA restrictions under Amendment 51. Self-regulate due to potential skin sensitization at high concentrations.
GHS Classification
RIFM Assessment
RIFM evaluation completed in 2015 – safe for use at current industry levels with recommended concentration limits.
Sustainability
As a purely synthetic material, 2-methylbutyraldehyde has minimal environmental impact in production. Modern synthesis routes using bio-based butenes are being developed to further reduce petrochemical dependence. Its high potency means very small quantities are needed, reducing transportation emissions compared to natural alternatives like galbanum resin.
Explore 2-Methylbutyraldehyde
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References
- Burdock, G.A. (2010). Fenaroli’s Handbook of Flavor Ingredients. CRC Press. ISBN 9781420090772
- Arctander, S. (1969). Perfume and Flavor Chemicals. Allured Publishing. ASIN B0006BXVT0
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorIngredient Data Sheet
CAS 96-17-3Physical Properties
| Molecular Weight | 86.13 g/mol🔬 PubChem |
| LogP (Octanol-Water) | 1.1🔬 PubChem |
| Boiling Point | 90 °C🔬 EPA CompTox |
| Vapor Pressure | 47.4 mmHg @ 25°C📊 OPERA |
| Flash Point | -5 °C🔬 EPA CompTox |
| Involatility Index | 5.5046💻 Calculated |
| log Kp (skin permeability) | -2.444💻 Calculated |
| SMILES | CCC(C)C=O🔬 PubChem |
Volatility & Performance
| Fragrance Note | Top💻 Calculated |
| Volatility Class | Very fast💻 Calculated |
| Persistence Score | 0.5 / 5💻 Calculated |
Odor & Flavor
| Primary Descriptors | fruitygreen• leffingwell |
| Functional Groups | aldehyde💻 RDKit |
| “Powerful, choking odor when undiluted, but in extreme dilution the odor becomes tolerable, almost pleasant fruity-"fermented" with a peculiar note resembling that of roasted Cocoa or Coffee.”📖 Arctander | |
| 2-Methylbutyraldehyde has a powerful, choking odor with a peculiar cocoa and coffee-like flavor when diluted. This compound is also reported to have a sweet, slightly fruity, chocolate-like taste.📖 Fenaroli | |
Flavor Notes (Arctander)
| “The taste is sweet, slightly fruity-chocolate-like in dilutions below 20 ppm. Pungent at higher concentrations. This aldehyde is used in flavor compositions as a special topnote ingredient for certain fruit notes, Cocoa, Chocolate, etc. It gives part of the "overripe" or "fermented" note to an Apple”📖 Arctander |
Sensory Thresholds
| Odor Detection Threshold | 0.0296 ppm (n=22)📖 van Gemert |
Regulatory Status
| FEMA Number | FEMA 2691⚖️ FEMA GRAS |
| GRAS Status | Generally Recognized as Safe⚖️ FEMA GRAS |
| IOFI Classification | Nature Identical📖 Fenaroli |
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: DTXSID2021818
Physical Properties
| Molecular Weight | 86.134 g/mol🔬 EPA CompTox |
| Density | 0.803 g/cm^3🔬 EPA CTX |
| Boiling Point | 91.5 °C🔬 EPA CTX |
| Melting Point | 65.833 °C🔬 EPA CTX |
| Flash Point | 0.288 °C🔬 EPA CTX |
| Refractive Index | 1.383 Dimensionless📊 OPERA |
| Molar Volume | 108.764 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 1.144 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 1.144 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 1.144 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 2.82 Log10 unitless📊 OPERA |
| Water Solubility | 0.151 mol/L🔬 EPA CTX |
| Henry's Law Constant | 0 atm-m3/mole🔬 EPA CTX |
Transport Properties
| Vapor Pressure | 52.202 mmHg🔬 EPA CTX |
| Viscosity | 0.479 cP📊 OPERA |
| Surface Tension | 23.096 dyn/cm📊 OPERA |
| Thermal Conductivity | 137.185 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 | 2 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 25.359 cm^3/mol📊 OPERA |
| Polarizability | 10.053 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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