Propionic acid CAS：79-09-4
Rich Chemical Reactivity:Propionic acid can take part in many kinds of chemical reactions such as esterification, neutralization and hydrogenation, which makes it widely applicable in different industrial fields.
Excellent Solubility:It dissolves completely in water and is also soluble in organic solvents including ethanol and chloroform, supporting flexible product formulation.
Safe and Stable Properties:It shows low toxicity with a rat LD₅₀ of 4.29 g/kg and stable chemical performance. Although it is flammable, it can be used safely in industry under proper control.
Unique Odor Feature:It has a strong, special smell similar to vinegar or mature cheese, which can be used as a distinguishing feature in practical applications.
Propanoic acid, commonly known as propionic acid, is a saturated short-chain fatty acid containing three carbon atoms and belongs to typical volatile carboxylic acids. With a molecular formula of CH₃CH₂COOH and a molecular weight of 74.08 g/mol, it appears as a colorless, clear oily liquid with a strong, sharp characteristic smell. Its key physical and chemical properties are as follows: freezing point -20.8°C, boiling point 140.99°C (41.65°C at 1.33 kPa), relative density 0.9930, and refractive index 1.3869.
| Melting point | −24-−23 °C(lit.) |
| Boiling point | 141 °C(lit.) |
| density | 0.993 g/mL at 25 °C(lit.) |
| vapor density | 2.55 (vs air) |
| vapor pressure | 2.4 mm Hg ( 20 °C) |
| refractive index | n20/D 1.386(lit.) |
| FEMA | 2924 | PROPIONIC ACID |
| Fp | 125 °F |
| storage temp. | Store below +30°C. |
| solubility | organic solvents: soluble(lit.) |
| pka | 4.86(at 25℃) |
| form | Liquid |
| Specific Gravity | 0.996 (20/4℃) |
| color | ≤10, APHA: |
| PH | 3.96(1 mM solution);3.44(10 mM solution);2.94(100 mM solution); |
| Odor | at 0.10 % in propylene glycol. pungent acidic cheesy vinegar |
| Odor Type | acidic |
| biological source | synthetic |
| Odor Threshold | 0.0057ppm |
| explosive limit | 2.1-12%(V) |
| Water Solubility | 37 g/100 mL |
| JECFA Number | 84 |
| Merck | 147,825 |
| BRN | 506071 |
| Exposure limits | TLV-TWA 10 ppm (～30 mg/m3) (ACGIH). |
| Dielectric constant | 3.2（Ambient） |
| Stability: | Stable. Incompatible with strong oxidizing agents. Flammable. |
| InChIKey | XBDQKXXYIPTUBI-UHFFFAOYSA-N |
| LogP | 0.33 at 25℃ |
| Surface tension | 24.07mN/m at 298.15K |
| CAS DataBase Reference | 79-09-4(CAS DataBase Reference) |
| NIST Chemistry Reference | Propanoic acid(79-09-4) |
| EPA Substance Registry System | Propionic acid (79-09-4) |
| Hazard Codes | C |
| Risk Statements | 36/37/38-34-10 |
| Safety Statements | 26-36-45-23 |
| RIDADR | UN 3463 8/PG 2 |
| OEB | A |
| OEL | TWA: 10 ppm (30 mg/m3), STEL: 15 ppm (45 mg/m3) |
| WGK Germany | 1 |
| RTECS | UE5950000 |
| Autoignition Temperature | 955 °F |
| TSCA | Yes |
| HazardClass | 8 |
| PackingGroup | II |
| HS Code | 29155010 |
| Hazardous Substances Data | 79-09-4(Hazardous Substances Data) |
| Toxicity | LD50 orally in rats: 4.29 g/kg (Smyth) |
