International name: Acetic acid, Ethanoic Acid

Synonyms: methane, ethane, glacial acid

Chemical formula: CH3COOH

Appearance: colorless liquid with a pungent odor and sour taste

Production: Poland, Russia

Packing and storage: eurocube, canister 10-20 liters; 1 st

 

Description

Acetic acid is a colorless liquid with a characteristic pungent odor and sour taste. It is hygroscopic. Unlimited soluble in water. Miscible with many solvents; in acetic acid, inorganic compounds and gases such as HF, HCl, HBr, HI and others are well soluble. It exists in the form of cyclic and linear dimers.
Absolute acetic acid is called ice-cold, because when it freezes, it forms an ice-like mass. Acetic acid is the first of the acids that has become known to mankind (in the form of vinegar, formed by souring wine). In concentrated form, it was obtained by Stahl in 1700, and the composition was established by Berzelius in 1814. Acetic acid is common in plants both in free form and in the form of salts and esters; it is formed when rotting and fermenting dairy products. The transformation of alcoholic liquids into vinegar (3-15% acetic acid) occurs under the influence of bacteria "acetic fungus" Micoderma aceti. From the fermented liquid, distillation produces 80% acetic acid - acetic essence. Acetic acid on a limited scale is obtained from "wood vinegar" - one of the products of dry distillation of wood.

 

Properties

Acetic, or methane carboxylic, ethanoic acid is a colorless liquid with a pungent odor and sour taste. Anhydrous acetic acid is called "ice cold". The melting point is 16, 75 ° C, the boiling point is 118, 1 °; 17, 1 ° at a pressure of 10 mm. gt; column, 42, 4 ° at 40 mm, 62, 2 ° at 100 mm, 98, 1 ° at 400 mm. and 109 ° at 560 mm. The specific heat of acetic acid is 0, 480 cal / g. deg., Q combustion 209, 4 kcal / mol.
Acetic acid has all the properties of carboxylic acids, and is sometimes regarded as their most typical representative (unlike formic acid, which has some properties of aldehydes). The bond between the hydrogen and oxygen of the carboxyl group (-COOH) of the carboxylic acid is strongly polar, so that these compounds are readily dissociable and exhibit acidic properties. Acetic acid in all respects is mixed with water, alcohol, ether, benzene and insoluble in carbon disulfide. When diluting acetic acid with water, the volume of the solution decreases. The maximum density of 1, 0748 g / cm3 corresponds to the monohydrate.

 

Receiving

Acetic acid (ethanoic acid) can be obtained in several ways:
 
• catalytic oxidation of acetaldehyde with oxygen in the presence of a catalyst at 56-75 ° C,
• in the industry, acetic acid is obtained from methanol and carbon monoxide (II),
• oxidation of n-butane at a temperature of 200 ° C and a pressure of 50 atm in the presence of a cobalt catalyst,
• biochemical production of acetic acid by fermentation (acetic fermentation).

Ethanol containing liquids (wine, fermented juices) and oxygen are used as raw materials. As auxiliary substances - enzymes of acetic acid bacteria or fungi (yeast).

Application

Acetic acid is used:

  • in the food industry (food additive E260) and household cooking, as well as in canning;
  • in typography and dyeing;
  • As a reaction medium for carrying out the oxidation of various organic substances;
  • in the textile industry when dyeing and printing fabrics;
  • in everyday life (removal of scale from kettles, care of surfaces);
  • in the chemical industry (as a solvent and chemical reagent)
  • in medicine (obtaining medicines)
  • in other industries

Safety requirements

The maximum permissible concentration of vapors of acetic acid in the air of the working area (MPC) is 5 mg / m3.
Determination of vapors of acetic acid in air is carried out by iodometric method. If the maximum permissible concentration is exceeded, the vapors of acetic acid act irritatingly on the mucous membrane of the upper respiratory tract; Acetic acid also causes skin burns.
When working with acetic acid, personal protective equipment should be used and personal hygiene rules should be observed.
Do not take acetic acid inside the body. Premises in which work is carried out with acetic acid, should be equipped with a general supply and exhaust mechanical ventilation. Work with acetic acid should be carried out away from the fire. In case of fire, for extinguishing foam PE-1D, PO-ZAI, Sampo, gas and powder formulations should be used.

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