Acetic acid, also known as acetic acid, is an organic compound with the chemical formula CH3COOH. It is an organic monobasic acid and is the main component of vinegar. Pure anhydrous acetic acid (glacial acetic acid) is a colorless hygroscopic liquid with a freezing point of 16.6 ℃ (62 ℉). After solidification, it becomes a colorless crystal. Its aqueous solution is weak acidic and corrosive, strongly corrosive to metals, and steam is irritating to eyes and nose.
Acetic acid is widely distributed in nature, for example, in fruits or vegetable oils, acetic acid mainly exists in the form of esters. Acetic acid exists as free acid in animal tissues, excreta and blood. Many microorganisms can convert different organic substances into acetic acid through fermentation
Industrial use
1. Acetic acid is a bulk chemical product and one of the most important organic acids. It is mainly used to produce acetic anhydride, acetate, cellulose acetate, etc. Polyvinyl acetate can be made into films and adhesives, and is also the raw material of synthetic fiber vinylon. Cellulose acetate can be used to make rayon and film.
2. Acetate formed from lower alcohols is an excellent solvent and is widely used in the paint industry. Because acetic acid dissolves most organic substances, acetic acid is also a commonly used organic solvent (for example, it is used for the oxidation of paraxylene to produce terephthalic acid).
3. Acetic acid can be used in some pickling and polishing solutions, as a buffer in weak acid solutions (such as zinc plating and chemical nickel plating), as an additive in semi bright nickel plating electrolyte, and in zinc and cadmium passivation solutions to improve the adhesion of the passive film, and is often used to adjust the pH of weak acid plating solutions.
4. It is used to produce acetate salts, such as manganese, sodium, lead, aluminum, zinc, cobalt and other metal salts, and is widely used as catalyst, auxiliary agent in fabric dyeing and leather tanning industry; Lead acetate is lead white paint color; Lead tetraacetate is an organic synthesis reagent (for example, lead tetraacetate can be used as a strong oxidant, a source of acetoxy group, and the preparation of organic lead compounds).
5. Acetic acid can also be used as analytical reagent, organic synthesis, pigment and drug synthesis.
Food use
In the food industry, when acetic acid is used as acidifier, aroma enhancer and spice to manufacture synthetic vinegar, dilute acetic acid to 4-5% with water and add various flavoring agents. The flavor is similar to that of alcohol vinegar, with short manufacturing time and low price. It can be used as a sour agent, and can be used as a compound condiment to prepare vinegar, canned food, jelly and cheese. It can be used moderately according to production needs. It can also be used as an aroma enhancer of fragrant wine, with the dosage of 0.1 ～ 0.3 g/kg.
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