Isopropyl propionate (CAS 637-78-5) — Sweet Top Note Fragrance Ingredient
Isopropyl propionate
CAS 637-78-5
What Is Isopropyl propionate?
Isopropyl propionate is a synthetic ester commonly used in fruity and floral fragrances. It provides a fresh, sweet, and slightly rum-like aroma. Consumers encounter it in body sprays, air fresheners, and functional perfumery. This ingredient matters because it adds a sparkling, effervescent quality to fragrances while being cost-effective and stable in formulations.
Safety Profile
GENERALLY SAFEWhat Does Isopropyl propionate Smell Like?
Isopropyl propionate offers a bright, fruity top note reminiscent of fresh apples and pears with a subtle rum-like undertone. The initial burst is effervescent and slightly green, evolving into a softer, sweeter heart that lingers briefly before dissipating cleanly. Its dry-down is neutral, making it an excellent carrier for other notes without overpowering them.
2D Molecular Structure
SMILES: CCC(=O)OC(C)C
Chemistry, Properties & Perfumer Guide
The Chemistry
Isopropyl propionate is an ester formed from isopropanol and propionic acid. It belongs to the class of aliphatic esters, known for their fruity and sweet olfactory characteristics. Industrially, it is synthesized via esterification under acidic conditions. Its simple structure contributes to high volatility and low persistence, making it ideal for top notes in fragrances.
Physical & Chemical Properties
| Boiling Point | 108-110 °C |
|---|---|
| Density | 0.865 g/cm³ |
| Flash Point | 12 °C |
| Refractive Index | 1.384 |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 1-5% | Up to 10% | Adds fruity freshness |
| Functional Fragrance | 5-15% | Up to 20% | Cost-effective top note |
| Air Fresheners | 10-20% | Up to 30% | Bright, clean opening |
Classic Accords
Tip: Use in citrus or fruity accords to enhance freshness without adding heaviness.
Alternatives & Comparisons
More intense fruity note, used when a stronger apple-pear effect is desired.
Longer-lasting with a sweeter, rum-like character, suitable for heart notes.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
No restrictions under IFRA standards.
GHS Classification
RIFM Assessment
RIFM assessment confirms safe use at current levels in fragrances.
Sustainability
Isopropyl propionate is synthesized from petrochemical feedstocks. Production is energy-efficient with minimal byproducts. Biodegradability is high, reducing environmental impact. Future green chemistry routes may utilize bio-based isopropanol.
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References
- PubChem Compound Summary for Isopropyl propionate CID 7918
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorPerfumer’s Notes
FEMA #: 2959 | IOFI #: Nature Identical
Isopropyl propionate has a bittersweet taste reminiscent of plum.
Odor: [‘ethereal’, ‘fruity’, ‘plum’, ‘rum’]
MW: 116.16
LogP: 1.4
Ingredient Data Sheet
CAS 637-78-5Physical Properties
| Molecular Weight | 116.16 g/mol🔬 PubChem |
| LogP (Octanol-Water) | 1.4🔬 PubChem |
| Boiling Point | 108 °C🔬 EPA CompTox |
| Vapor Pressure | 22.532 mmHg @ 25°C📊 OPERA |
| Involatility Index | 2.2532💻 Calculated |
| log Kp (skin permeability) | -2.415💻 Calculated |
| SMILES | CCC(=O)OC(C)C🔬 PubChem |
Volatility & Performance
| Fragrance Note | Top💻 Calculated |
| Volatility Class | Fast💻 Calculated |
| Persistence Score | 0.5 / 5💻 Calculated |
Odor & Flavor
| Primary Descriptors | etherealfruityplumrum• leffingwell |
| Functional Groups | esterether💻 RDKit |
| “Fresh-ethereal, fruity odor with fermented-winey note and poor tenacity. Fruity, Rum-like taste in concentrations lower than 100 ppm. This ester is probably not used in perfumes.”📖 Arctander | |
| Isopropyl propionate has a bittersweet taste reminiscent of plum.📖 Fenaroli | |
Flavor Notes (Arctander)
| “Fresh-ethereal, fruity odor with fermented-winey note and poor tenacity. Fruity, Rum-like taste in concentrations lower than 100 ppm. This ester is probably not used in perfumes. It finds some use in flavor compositions, mainly in fruit complexes, "tutti-frutti"-types, Rum imitation, etc. It produce”📖 Arctander |
Sensory Thresholds
| Odor Detection Threshold | 0.0042 ppm📖 van Gemert |
Regulatory Status
| FEMA Number | FEMA 2959⚖️ 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: DTXSID6060927
Physical Properties
| Molecular Weight | 116.16 g/mol🔬 EPA CompTox |
| Density | 0.866 g/cm^3🔬 EPA CTX |
| Boiling Point | 109.5 °C🔬 EPA CTX |
| Melting Point | -84.197 °C📊 OPERA |
| Flash Point | 20.456 °C📊 OPERA |
| Refractive Index | 1.396 Dimensionless📊 OPERA |
| Molar Volume | 131.435 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 1.709 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 1.709 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 1.709 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 3.24 Log10 unitless📊 OPERA |
| Water Solubility | 0.051 mol/L🔬 EPA CTX |
| Henry's Law Constant | 0.001 atm-m3/mole🔬 EPA CTX |
Transport Properties
| Vapor Pressure | 22.532 mmHg🔬 EPA CTX |
| Viscosity | 0.622 cP📊 OPERA |
| Surface Tension | 23.982 dyn/cm📊 OPERA |
| Thermal Conductivity | 130.261 mW/(m*K)📊 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 | 2 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 31.58 cm^3/mol📊 OPERA |
| Polarizability | 12.519 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.
