Propionic acid

The propionic acid or propionic acid , is an organic acid monoprotic , three atom of carbon , can be found naturally. Its formula is CH 3 – COOH (C 2 H 4 O 2 ), in its pure state it is a colorless and corrosive liquid.


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  • 1 General
  • 2 Physical properties
  • 3 Chemical properties
  • 4 Industrial synthesis
  • 5 Applications
  • 6 Risks
  • 7 Sources


Propanoic acid was initially described in 1844 by Johann Gottlieb , who found it among the products of sugar breakdown. later other chemists synthesized it with other methods, but without obtaining the same substance. In 1847 the French chemist Jean-Baptiste Dumas established that all acids were the same compound. He called it propionic acid, from the Greek words protos (first) and pion (fat) because it was the smallest fatty acid of formula H (CH 2 ) n COOH that exhibited the characteristics of the other fatty acids.

Physical properties

  • It is a liquid acid
  • Colorless
  • Smell acrid
  • Boiling point of -21.15 ° C
  • Melting point of 140.85 ° C

Chemical properties

  • Miscible in water
  • Dipole momentof 0.63 D

Industrial synthesis

It is obtained from oxidation to air, propanal and in the presence of cobalt or manganese cations, this reaction proceeds quickly even at low temperatures. This process is normally carried out at temperatures between 40 ° C and 50 ° C, and is represented by the following equation:

3 C-CH 2 -CHO + ½ O 2 → H 3 C-CH 2 -COOH

In the past, large amounts of propyl acid were produced as a by-product of acetic acid. But the changes in the method of production of acetic acid have made this a minor source today. Biologically, bacteria of the genus propionibacterium produce propionic acid as the end product of its anaerobic metabolism. These bacteria are commonly found in the stomachs of ruminants, and their activity is partially responsible for the smell of Swiss cheese and sweat.


  • It is used as a preservative, propanoic acid inhibits the growth of mold and some bacteria, a large amount is intended for the preservation of feed and food for human consumption.
  • In antifungal powder for the feet.
  • It is used to modify synthetic cellulose fibers.
  • In the production of pesticides and pharmaceuticals.


  • Chemical burns that can occur on contact with the concentrated liquid.
  • Ulceration of the esophagus and stomach due to consumption.
  • In the body it is rapidly oxidized, metabolized, and eliminated from the body as carbon dioxide in the Krebs cycle, and therefore is not bioaccumulative.


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