Propionaldehyde (CAS 123-38-6) — Green Top Note Fragrance Ingredient
Propionaldehyde
CAS 123-38-6
What Is Propionaldehyde?
Propionaldehyde is a synthetic organic compound with a sharp, pungent odor reminiscent of green apples and plastic. You might encounter it in industrial settings, as a flavoring agent in very low concentrations, or as a trace component in some perfumes. This aldehyde matters in perfumery as a building block for more complex molecules and for adding crisp, fruity-green top notes when used cautiously.
Safety Profile
PROFESSIONAL USEWhat Does Propionaldehyde Smell Like?
Propionaldehyde assaults the nose with an intensely sharp, piercing greenness – like the first bite into an unripe Granny Smith apple crossed with the acrid tang of melted plastic. The opening is aggressively chemical, with a metallic edge that can border on unpleasant at higher concentrations. As it evaporates, it reveals a fleeting fruity character reminiscent of pear drops before fading into a faint, slightly rancid fatty note. In dilution, it contributes a crisp, diffusive quality that works well to ‘lift’ citrus and green accords.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used in trace amounts to enhance the citrusy freshness and green herbal character. Its sharpness helps cut through the bergamot and rosemary to create a more vibrant, modern interpretation of a cologne.
Employed as part of the ‘green bomb’ effect, contributing to the hyper-realistic crushed leaves and stems impression that made this fragrance revolutionary for its time.
2D Molecular Structure
SMILES: CCC=O
Chemistry, Properties & Perfumer Guide
The Chemistry
Propionaldehyde (propanal) is the simplest aliphatic aldehyde after formaldehyde and acetaldehyde. This volatile organic compound consists of a three-carbon chain with a terminal formyl group. Industrially produced by hydroformylation of ethylene or oxidation of propanol, it serves primarily as an intermediate in plasticizer and rubber chemical production. In perfumery, its high reactivity makes it more valuable as a precursor than as a direct ingredient – it readily undergoes aldol condensations to form more stable fragrance molecules.
Physical & Chemical Properties
| Boiling Point | 48-50 °C |
|---|---|
| Flash Point | -30 °C |
| Density | 0.81 g/cm³ |
| Vapor Pressure | 328 mmHg at 20°C |
| Appearance | Colorless liquid |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.01-0.1% | Up to 0.5% | Used in minute quantities for lift |
| Functional Products | 0.001-0.01% | Trace | Avoid in leave-on products |
Classic Accords
Tip: Always add drop by drop to ethanol base – its intensity can easily overwhelm a blend.
Alternatives & Comparisons
Provides similar green character with less harshness and more natural leaf-like qualities. Better for consumer products where propionaldehyde would be too aggressive.
Another short-chain aldehyde that offers fruity-green notes but with more diffuse, less piercing effect. Preferable when working with floral bases.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
Not specifically restricted by IFRA, but general aldehyde precautions apply. Use limited by irritation potential.
EU Allergen Declaration
Not listed as an EU allergen, but declaration recommended at >0.01% due to irritation potential.
GHS Classification
RIFM Assessment
RIFM evaluation confirms need for strict usage limits due to irritation potential. Not recommended for leave-on products above 0.01%.
Sustainability
As a petrochemical derivative, propionaldehyde production has significant carbon footprint. However, its extreme potency means total volumes used are negligible compared to other fragrance ingredients. Some bio-based production routes exist via fermentation of sugars to propanol followed by oxidation, but these are not yet commercially significant.
Explore Propionaldehyde
Browse essential oils and aroma compounds.
Browse on iHerb →Affiliate disclosure: we may earn a small commission at no extra cost to you.
References
- Burdock, G.A. (2010). Fenaroli’s Handbook of Flavor Ingredients. CRC Press. ISBN 9781420090869
- PubChem Propionaldehyde CID 527
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorIngredient Data Sheet
CAS 123-38-6Physical Properties
| Molecular Weight | 58.08 g/mol🔬 PubChem |
| LogP (Octanol-Water) | 0.6🔬 PubChem |
| Boiling Point | 48.9 °C🔬 EPA CompTox |
| Vapor Pressure | 235 mmHg @ 25°C📊 OPERA |
| Flash Point | -9.4 °C🔬 EPA CompTox |
| Involatility Index | 33.234💻 Calculated |
| log Kp (skin permeability) | -2.628💻 Calculated |
| SMILES | CCC=O🔬 PubChem |
Volatility & Performance
| Fragrance Note | Top💻 Calculated |
| Volatility Class | Very fast💻 Calculated |
| Persistence Score | 0.5 / 5💻 Calculated |
Odor & Flavor
| Primary Descriptors | green• leffingwell |
| Functional Groups | aldehyde💻 RDKit |
| “Very diffusive and penetrating, suffocating odor with choking effect upon the respiratory system. Very poor tenacity. In extreme dilution an odor of roasted Coffee appears.”📖 Arctander | |
Flavor Notes (Arctander)
| “Since the material is water-soluble, its flavor effect in aqueous media is not so enormous. Concentrations near 10 ppm have a sweet-ethereal, green-caramellic taste. Higher con- centrations tend to give burning mouthfeel or pungent taste. It is used in flavor compositions for its lifting-ethereal ef”📖 Arctander |
Sensory Thresholds
| Odor Detection Threshold | 0.2774 ppm (n=5)📖 van Gemert |
Regulatory Status
| FEMA Number | FEMA 2923⚖️ FEMA GRAS |
| 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: DTXSID2021658
Physical Properties
| Molecular Weight | 58.08 g/mol🔬 EPA CompTox |
| Density | 0.816 g/cm^3🔬 EPA CTX |
| Boiling Point | 48.364 °C🔬 EPA CTX |
| Melting Point | -75.361 °C🔬 EPA CTX |
| Flash Point | -25.205 °C🔬 EPA CTX |
| Refractive Index | 1.348 Dimensionless📊 OPERA |
| Molar Volume | 75.374 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 0.573 Log10 unitless🔬 EPA CTX |
| LogD (pH 5.5) | 0.585 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 0.585 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 3.02 Log10 unitless🔬 EPA CTX |
| Water Solubility | 4.139 mol/L🔬 EPA CTX |
| Henry's Law Constant | 0 atm-m3/mole🔬 EPA CTX |
Transport Properties
| Vapor Pressure | 296 mmHg🔬 EPA CTX |
| Viscosity | 0.437 cP📊 OPERA |
| Surface Tension | 21.616 dyn/cm📊 OPERA |
| Thermal Conductivity | 149.586 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 | 16.134 cm^3/mol📊 OPERA |
| Polarizability | 6.396 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.
![2-[(3,3,5-Trimethylcyclohexyl)acetyl]cyclopentan-1-one (CAS 84642-57-9) — Woody Heart to base Note Fragrance Ingredient](https://thegoodscents.company/wp-content/uploads/2026/04/2-1-23-768x439.webp)
