Isobutyl formate (CAS 542-55-2) — Sweet Top Note Fragrance Ingredient
Isobutyl formate
CAS 542-55-2
What Is Isobutyl formate?
Isobutyl formate is a synthetic ester commonly used in fruit flavorings and fragrances. You’ll encounter it in candies, beverages, and perfumes with bright, fruity notes. This ingredient matters because it delivers an intense, natural-smelling fruitiness that’s hard to replicate with other compounds. Its sharp, refreshing character makes it indispensable for creating realistic berry and tropical fruit accords.
Safety Profile
GENERALLY SAFEWhat Does Isobutyl formate Smell Like?
Isobutyl formate bursts with a piercing, almost effervescent fruitiness – imagine raspberries crushed with sparkling water. The opening is aggressively sweet with a green, slightly fermented edge like overripe strawberries. As it evolves, the harshness mellows into a clean, jammy heart with whispers of pineapple and banana. The dry-down reveals a faint woody undertone, but most of its character evaporates quickly, leaving just a memory of fruit leather on warm skin.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used in the explosive top note to amplify the grapefruit and marine accord, creating an energizing fruit cocktail effect that defines this modern masculine.
Provides the hyper-realistic raspberry note in this fruity floral, blending with rose to create a candied berry effect that lasts through the heart notes.
2D Molecular Structure
SMILES: CC(C)COC=O
Chemistry, Properties & Perfumer Guide
The Chemistry
Isobutyl formate belongs to the ester family, formed through Fischer esterification of isobutanol with formic acid. This simple ester lacks chirality but shows remarkable volatility due to its low molecular weight. Industrial production typically uses acid-catalyzed reactions between the alcohol and carboxylic acid, with yields optimized through azeotropic distillation to remove water.
Physical & Chemical Properties
| Appearance | Colorless liquid |
|---|---|
| Boiling Point | 98-100 °C |
| Density | 0.885 g/cm³ |
| Refractive Index | 1.386-1.388 |
| Flash Point | 12 °C (closed cup) |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.5-2% | Up to 5% | Used sparingly for fruity top notes |
| Functional Fragrance | 0.1-0.5% | Up to 1% | For fruity household products |
Classic Accords
Tip: Stabilize with antioxidants to prevent ester hydrolysis in aqueous systems.
Alternatives & Comparisons
Similar fruity character but more banana-like, with better longevity. Use when a less aggressive top note is needed.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
Not restricted by IFRA – no usage limits apply.
GHS Classification
RIFM Assessment
RIFM evaluation confirms safe use at current industry levels with no sensitization concerns.
Sustainability
Synthesized from petrochemical feedstocks but requires minimal energy input due to simple production process. Biodegradability studies show rapid breakdown in aquatic environments (80% degradation in 28 days). No known ecological toxicity at usage concentrations.
Explore Isobutyl formate
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References
- Burdock, G.A. (2010). Fenaroli’s Handbook of Flavor Ingredients. CRC Press. ISBN 9781420090869
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorPhysicochemical Properties
DTXSID: DTXSID7060257
Physical Properties
| Molecular Weight | 102.133 g/mol🔬 EPA CompTox |
| Density | 0.893 g/cm^3📊 OPERA |
| Boiling Point | 98.1 °C🔬 EPA CTX |
| Melting Point | -95.267 °C🔬 EPA CTX |
| Flash Point | 17.6 °C🔬 EPA CTX |
| Refractive Index | 1.387 Dimensionless📊 OPERA |
| Molar Volume | 115.127 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 1.154 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 1.154 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 1.154 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 2.75 Log10 unitless📊 OPERA |
| Water Solubility | 0.099 mol/L🔬 EPA CTX |
| Henry's Law Constant | 0.001 atm-m3/mole🔬 EPA CTX |
Transport Properties
| Vapor Pressure | 40.179 mmHg🔬 EPA CTX |
| Viscosity | 0.637 cP📊 OPERA |
| Surface Tension | 24.533 dyn/cm📊 OPERA |
| Thermal Conductivity | 141.295 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 | 3 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 27.104 cm^3/mol📊 OPERA |
| Polarizability | 10.745 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.
