Benzoic acid

A chemist, using the fact that benzoic acid has the ability to sublimate, can at any time of the year arrange a "winter garden" on the laboratory table. To do this, under a glass cap on a plywood board, fix the branches of coniferous plants and put a cup in which there is benzoic acid in the hole made in the middle of it. When the calyx is heated from below by the flame of the alcohol lamp, it sublimes. After passing into the vapor state, it immediately starts in the air crystallize. This creates an impression of a snowy blizzard. At the same time, benzoic acid covers the coniferous branches with white fluffy crystals.

A chemist, using the fact that benzoic acid has the ability to sublimate, can at any time of the year arrange a winter garden on the laboratory table

Benzoic acid C6H5COOH was first isolated by sublimation in the 16th century from benzoic resin (dew incense), hence its name. This process was described in Nostradamus (1556). In 1832, the German chemist Justus von Liebig determined its structure. In 1875 the German physiologist Ernst Leopold Zalkovsky investigated the antifungal properties of benzoic acid, which for a long time was used in canning fruits.

Benzoic acid is prepared by oxidation of toluene with potassium permanganate, chromium oxide (6), nitric or chromic acid, as well as decarboxylation of phthalic acid. On an industrial scale, benzoic acid is obtained by oxidizing toluene with oxygen, with the participation of cobalt.

Benzoic acid is used as a chemical standard for calibration calorimeters by temperature and heat capacity. Benzoic acid and its salts are used for canning food products (food additives E210, E211, E212, E213). It, by blocking enzymes, slows the metabolism in unicellular organisms and suppresses the growth of mold, yeast and some bacteria. It is added directly or in the form of sodium, potassium or calcium salt. The mechanism of action begins with the absorption of benzoic acid cell. Since only undissociated acid can penetrate through the cell wall, benzoic acid exhibits antimicrobial activity only in acidic food products.

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