Propyl isovalerate (CAS 557-00-6) — Sweet Top Note Fragrance Ingredient
Propyl isovalerate
CAS 557-00-6
What Is Propyl isovalerate?
Propyl isovalerate is a synthetic ester commonly used in fruity and apple-like fragrance compositions. You’ll encounter it in fresh, sweet perfumes and some flavorings. This ingredient matters because it adds a crisp, juicy quality to fragrances, mimicking natural fruit aromas while being more stable and consistent than natural extracts.
Safety Profile
GENERALLY SAFEWhat Does Propyl isovalerate Smell Like?
Propyl isovalerate bursts with a bright, fruity aroma reminiscent of green apples and ripe pears. The top note is intensely fresh, like biting into a just-picked Granny Smith apple with a hint of banana-like sweetness. As it evolves, it reveals a subtle creamy undertone, similar to pear drops candy, before drying down to a faint, clean fruitiness that lingers softly. The overall effect is juicy and uplifting without being cloying, making it perfect for creating naturalistic fruit accords.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used to enhance the crisp apple note in this fresh aquatic fragrance, adding juicy realism to the citrus top notes while maintaining transparency.
Provides subtle fruity lift to the citrus-green tea accord, creating a refreshing, slightly sweetened effect reminiscent of iced fruit tea.
Chemistry, Properties & Perfumer Guide
The Chemistry
Propyl isovalerate is an ester formed from the condensation of propanol and isovaleric acid. As a synthetic material, it’s typically produced via acid-catalyzed esterification. The molecule’s simple structure (C8H16O2) gives it high volatility and excellent diffusion. While not found in significant quantities in nature, its fruity character makes it valuable for reconstructing apple and pear aromas. The ester’s stability and low molecular weight contribute to its bright, immediate olfactory impact.
Physical & Chemical Properties
| Boiling Point | ~160-165 °C (estimated) |
|---|---|
| Density | ~0.86 g/cm³ (estimated) |
| Solubility | Slightly soluble in water, miscible with alcohols and oils |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.5-3% | Up to 5% | Fruity top note enhancement |
| Functional Fragrance | 0.1-1% | Up to 2% | Fresh fruit nuances in detergents |
| Flavorings | 10-50 ppm | Up to 100 ppm | Apple/pear flavor modifier |
Classic Accords
Tip: Use in trace amounts with citrus oils to create natural-seeming fruit effects without overwhelming the composition.
Alternatives & Comparisons
More volatile with sharper green apple character, useful when brighter top notes are needed.
Provides similar fruity effects but with more pear-like nuance and longer persistence.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
Not restricted under current IFRA standards (Amendment 49).
RIFM Assessment
Considered safe for current fragrance use levels based on RIFM evaluation.
Sustainability
As a synthetic material, propyl isovalerate offers consistent quality without agricultural variability. Its production from petrochemical feedstocks raises some environmental considerations, but its high potency means only small quantities are needed compared to natural extracts. No known significant ecological toxicity at usage levels.
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References
- Burdock, G.A. (2010). Fenaroli’s Handbook of Flavor Ingredients. CRC Press.
- Arctander, S. (1969). Perfume and Flavor Chemicals. Allured Publishing.
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
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