Propanoic acid (other names - methylacetic acid, preservative E280, propionic acid) is a colorless liquid with a pungent unpleasant odor. It has the following chemical formula: C2H5-COOH.
Physical properties of propionic acid:
1. The melting point is -21 °.
2. The boiling point is 141 °.
3. The flash point is 54 °.
4. The molar mass is 74.08 gram / mol.
5. Under standard conditions, it is a colorless liquid.
6. The autoignition temperature is 440 °.
Chemical properties of propionic acid:
1. Miscible with water (H2O) and organic solvents.
2. Propanoic acid is a typical representative of carboxylic saturated acids. It can form esters, halides, amides and other substances.
The history of the discovery of propanoic acid
This substance was first described in 1844 by Gottlieb Johan, who found it among sugar decomposition products. Then, for some time, other chemical scientists obtained this acid in different ways, without realizing that they produced the same compound. And in 1847, Jean-Baptiste Dumas established that the previously obtained substances were the same acid, which he later named as propanoic acid, the formula of which is C2H5-COOH.
What are the methods for producing propanoic acid?
In nature, propanoic acid is found in oil.
In industry, this substance is obtained by carbonylation of ethylene by the Repp reaction as a by-product in the oxidation of carbon, catalytic oxidation of propane aldehyde in the presence of manganese or cobalt ions.
Also, a large amount of methyl acetic acid can be obtained in the production of acetic acid, however, modern methods of preparation have made this method a secondary source of propanoic acid.
This substance can be obtained by metabolic decomposition of amino acids and fatty acids, which contain an odd number of carbon atoms.
Propanoic acid is also produced by bacteria of the genus Propionibacterium (as the final product of its metabolism). These bacteria are found in the digestive system of ruminants, and it is because of their activity that Swiss cheese has its own unique flavor.
Propionic Acid Derivatives
These are esters and salts.
Alkaline earth and alkaline salts are highly soluble in water (H2O), not soluble in organic solvents.
The esters of this substance are poorly soluble in (H2O) water, but miscible with organic solvents.
Application
This acid is used in the following cases:
- production of herbicides (for example, dichloroprol, propanol), drugs (phenobolin, ibuprofen), some fragrances (linaloyl, phenyl, geranyl, benzyl propionates), solvents (butyl, pentyl, propyl propionate), plastics ( polyvinyl propionate), surfactants (glycol ethers) and vinyl plasticizers;
- since propanoic acid inhibits the growth of certain bacteria and mold, most of it is used as a preservative in food products for both humans and animals. Propionic acid or its salt (ammonium propionate) is used directly in animal products, and calcium (calcium propionate) or sodium (sodium propionate) or salts are used in products that are made for humans.
Safety at work
The main danger when working with propionic acid is chemical burns of varying severity.
In studies conducted on laboratory animals, the only negative effect associated with the long-term consumption of small doses of propanoic acid was the appearance of ulcers in the esophagus and stomach, due to the corrosive properties of the substance. During the experiment, it was not found that propanoic acid is mutagenic, carcinogenic, toxic and adversely affects the reproductive organs. Once in the body, the substance we are considering is rapidly oxidized, metabolized, and then excreted in the form of carbon dioxide.