benzoic acid - is the simplest representative of the class of carboxylic acids or organic chemical formula C6H5COOH.This chemical compound can be said that it is formed by replacing one hydrogen atom attached to a carbon atom of the benzene ring to a carboxy group.
Benzoic acid in appearance is a colorless crystalline solid with a density of 1.27 g / cm³ and a molecular weight of 122.1 g / mole.Melting C6H5COOH equals 122.41 ° C and the boiling - 249.2 ° C.In 1 liter of water is able to dissolve 2.9 g of material C6H5COOH.Acidity is 4.202, the refractive index is 1.5397.
name comes from benzoin, from which in the 16th century (it was first described by Nostradamus in 1556, and later Blaise de Vigenère in 1596), a substance first isolated by sublimation.For a long time it is a natural compound remained the only source of acid.
In 1832, chemist J. von Liebig was first described the structure of benzoic acid, and in 1875 the German physiologist Ernst Leopold Zalkovskim studied its antifungal and antiseptic properties.The salts used as food preservatives, benzoic acid and itself is an important raw material for the synthesis of many other organic compounds.Many housewives and today use the unique abilities of the carboxylic acid to long-term storage of berries cranberries without additional preservatives (even without the addition of sugar), or special processing methods.
esters and salts of benzoic acid known as benzoate.Qualitative characteristics and aromatic carboxylic acids combines benzoic acid.Its chemical properties are determined by the presence of the aromatic ring and a carboxyl group.
aromatic ring characterized electrophilic substitution reaction mainly for the third carbon atom, the location of which is determined relative to the carboxyl group.
second scheme is a substitution reaction at the place of the hydrogen in the carboxyl group and is slower.
All reactions mentioned for carboxylic acids, are also characteristic of C6H5COOH.
Due to the unique antiseptic and antifungal properties, benzoic acid is used in canning.It is used as a number of food additives E210-E213.Benzoic acid blocks the enzymes and metabolism of harmful unicellular organisms.Through its action inhibited the growth of yeasts, molds and many disease-causing bacteria.Use benzoic acid or its sodium, potassium or calcium salts.
substance capable of exhibiting antimicrobial activity only in acidic foods.If intracellular pH less than or equal to 5, the anaerobic fermentation of glucose is reduced by 95%.Efficacy acid and benzoates pH dependent food.Fruit juices (containing citric acid), sparkling drinks (containing CO2), soft drinks (containing phosphoric acid), pickles (acetic acid) or other preserved foods acidification acid and its salts.Optimal concentrations in the preservation of food are in the range of 0.05-0.1%.
toluene-based mostly synthesized benzoic acid.Preparation it flows through the reaction scheme with potassium permanganate oxidation of methylbenzene.On a commercial basis is a unique organic compound is produced through the partial oxidation of toluene with oxygen.The process takes place at a special catalyst.For laboratories benzoic acid is cheap and available reagent.For all syntheses, it may be purified by recrystallization from aqueous solution.In this case, a property of high solubility in hot water and poor solubility in cold water.
Benzoic acid is widely used as a preservative in food, medicine and organic synthesis based on it are obtained various organic substances, including dyes.Also, it is used in the chemical industry or in the practice of analytical laboratories.
