Propionic acid
Versatile Chemical Reactivity: Propionic acid participates in diverse chemical transformations including esterification processes, neutralization reactions, and hydrogenation operations, demonstrating adaptability for multiple industrial applications.
Broad Solubility Profile: Exhibits complete miscibility with aqueous systems while maintaining solubility in organic solvents such as ethanol and chloroform, enabling flexible formulation development.
Controlled Handling Characteristics: Demonstrates relatively low toxicity (documented rat LD₅₀: 4.29 g/kg) and stable chemical properties, ensuring safe industrial utilization under regulated conditions despite inherent flammability.
Distinct Olfactory Signature: Possesses a characteristic pungent aroma reminiscent of vinegar or aged cheese, serving as a recognizable identifier in various applications.
Propionic acid, systematically named propanoic acid, is a three-carbon saturated fatty acid representing a typical volatile short-chain carboxylic acid. Its molecular formula is CH₃CH₂COOH with a molecular weight of 74.08 g/mol. This compound presents as a colorless, transparent oily liquid possessing a characteristic pungent odor. It exhibits the following physicochemical properties: freezing point -20.8°C, boiling point 140.99°C (41.65°C at 1.33 kPa), specific gravity 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 | 14,7825 |
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) |
Safety Information
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) |
The acid dissociation constant (Ka) measures 1.34 × 10⁻⁵. It demonstrates complete miscibility with water and readily dissolves in ethanol, chloroform, and diethyl ether. The compound displays characteristic carboxylic acid reactivity, participating in various chemical transformations including neutralization reactions, ester formation, and hydrogenation processes.
