Formic acid (CAS 64-18-6) — Citrus N/A Note Fragrance Ingredient
Formic acid
CAS 64-18-6
What Is Formic acid?
Formic acid is a sharp, pungent chemical most commonly encountered in ant venom and some industrial cleaners. While not typically used in fine fragrances, it appears in trace amounts as a volatile component in certain natural materials. This simple carboxylic acid matters in perfumery primarily as a building block for more complex aroma chemicals and as a natural component that must be accounted for in fragrance analysis.
Safety Profile
PROFESSIONAL USEWhat Does Formic acid Smell Like?
Formic acid delivers an intensely sharp, acrid odor reminiscent of vinegar’s harsher cousin with metallic undertones. The scent profile is linear and persistent, lacking any evolution – a piercing, nose-stinging acidity that dominates any composition. At extreme dilution, it can contribute a fermented, animalic nuance, but generally overwhelms delicate fragrance structures with its aggressive chemical character.
2D Molecular Structure
SMILES: OC=O
Chemistry, Properties & Perfumer Guide
The Chemistry
Formic acid (methanoic acid) is the simplest carboxylic acid with the formula HCOOH. While naturally occurring in ant venom and some plant secretions, commercial production typically involves methyl formate hydrolysis or as a byproduct of acetic acid manufacture. The molecule exhibits strong hydrogen bonding and exists as a dimer in the gas phase. Its high acidity (pKa 3.75) and small molecular size contribute to its volatility and penetrating odor characteristics.
Physical & Chemical Properties
| Boiling Point | 100.8 °C |
|---|---|
| Density | 1.22 g/cm³ |
| pKa | 3.75 |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Industrial | Not applicable | Not applicable | Primarily chemical intermediate |
Classic Accords
Tip: Avoid direct use in fragrance compositions due to corrosivity and overpowering odor.
Alternatives & Comparisons
Offers similar acidity with slightly more tolerable odor profile for fermentation effects.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
Not regulated by IFRA but unsuitable for fragrance use due to safety concerns.
GHS Classification
RIFM Assessment
Not evaluated by RIFM for fragrance use due to inherent hazards.
Sustainability
Industrial production from fossil feedstocks raises environmental concerns. Some bio-based production methods exist via formate dehydrogenase enzymes, but these are not yet commercially significant. Proper handling and disposal are critical due to its corrosive nature.
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References
- PubChem Compound Summary for Formic acid PubChem CID 284
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorIngredient Data Sheet
CAS 64-18-6Physical Properties
| Molecular Weight | 46.025 g/mol🔬 PubChem |
| LogP (Octanol-Water) | -0.2🔬 PubChem |
| Boiling Point | 100.7 °C🔬 EPA CompTox |
| Vapor Pressure | 35 mmHg @ 25°C📊 OPERA |
| Flash Point | 68.9 °C🔬 EPA CompTox |
| Involatility Index | 5.5603💻 Calculated |
| log Kp (skin permeability) | -3.123💻 Calculated |
| SMILES | C(=O)O🔬 PubChem |
Volatility & Performance
| Fragrance Note | Top💻 Calculated |
| Volatility Class | Very fast💻 Calculated |
| Persistence Score | 0.5 / 5💻 Calculated |
Odor & Flavor
| Primary Descriptors | pungent• leffingwell |
| “Pungent odor giving a stinging sensation on the mucous membranes. Sour taste in proper dilution – lower than 50 ppm without stinging or burning.”📖 Arctander | |
| Formic acid has a pungent, penetrating odor. Formic acid is the first member of the homologous series identified as fatty acids with general formula RCOOH. This acid was obtained first from the red ants; its common name is derived from the family name for ants, Formicidae. This substance also occurs naturally in bees and wasps and is presumed to be responsible for the sting of these insects.📖 Fenaroli | |
Flavor Notes (Arctander)
| “Miscible with water, alcohol, Propylene glycol, Glycerin, perfume and flavor oils. Pungent odor giving a stinging sensation on the mucous membranes. Sour taste in proper dilution – lower than 50 ppm without stinging or burning. This acid finds use in flavors, usually NOT incorporated in the flavor c”📖 Arctander |
Sensory Thresholds
| Odor Detection Threshold | 48.223 ppm (n=24)📖 van Gemert |
Regulatory Status
| FEMA Number | FEMA 2487⚖️ 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: DTXSID2024115
Physical Properties
| Molecular Weight | 46.025 g/mol🔬 EPA CompTox |
| Density | 1.213 g/cm^3🔬 EPA CTX |
| Boiling Point | 102.639 °C🔬 EPA CTX |
| Melting Point | 3.229 °C🔬 EPA CTX |
| Flash Point | 57.378 °C🔬 EPA CTX |
| Refractive Index | 1.342 Dimensionless📊 OPERA |
| Molar Volume | 39.867 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | -0.852 Log10 unitless🔬 EPA CTX |
| LogD (pH 5.5) | -2.337 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | -4.102 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 2.62 Log10 unitless📊 OPERA |
| Water Solubility | 20.943 mol/L🔬 EPA CTX |
| Henry's Law Constant | 0 atm-m3/mole🔬 EPA CTX |
Transport Properties
| Vapor Pressure | 36.349 mmHg🔬 EPA CTX |
| Viscosity | 1.014 cP📊 OPERA |
| Surface Tension | 33.173 dyn/cm📊 OPERA |
| Thermal Conductivity | 217.219 mW/(m*K)📊 OPERA |
Molecular Descriptors
| Topological Polar Surface Area | 37.3 Ų💻 Computed |
| H-Bond Donors | 1 count💻 Computed |
| H-Bond Acceptors | 1 count💻 Computed |
| Rotatable Bonds | 0 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 8.404 cm^3/mol📊 OPERA |
| Polarizability | 3.331 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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