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Benzoic acid and its salts are used as food preservatives, represented by the E numbers E210, E211, E212, and E213. Benzoic acid inhibits the growth of mold, yeast [23] and some bacteria. It is either added directly or created from reactions with its sodium, potassium, or calcium salt. The mechanism starts with the absorption of benzoic acid ...
Included in that class are substances containing a phenolic ring and an organic carboxylic acid function (C6-C1 skeleton). Two important naturally occurring types of phenolic acids are hydroxybenzoic acids and hydroxycinnamic acids, which are derived from non-phenolic molecules of benzoic and cinnamic acid, respectively. [1]
Phenol (also known as carbolic acid, phenolic acid, or benzenol) is an aromatic organic compound with the molecular formula C 6 H 5 OH. [5] It is a white crystalline solid that is volatile . The molecule consists of a phenyl group ( −C 6 H 5 ) bonded to a hydroxy group ( −OH ).
It is often said the resonance stability of phenol makes it a stronger acid than that of aliphatic alcohols such as ethanol (pK a = 10 vs. 16–18). However, a significant contribution is the greater electronegativity of the sp 2 alpha carbon in phenol compared to the sp 3 alpha carbon in aliphatic alcohols. [7]
It oxidizes rapidly in healthy individuals to benzoic acid, conjugated with glycine in the liver, and excreted as hippuric acid. Very high concentrations can result in toxic effects including respiratory failure, vasodilation, hypotension, convulsions, and paralysis. Benzyl alcohol is toxic to neonates and is associated with the gasping syndrome.
The acidity of the hydroxyl group in phenols is commonly intermediate between that of aliphatic alcohols and carboxylic acids (their pK a is usually between 10 and 12). Deprotonation of a phenol forms a corresponding negative phenolate ion or phenoxide ion , and the corresponding salts are called phenolates or phenoxides ( aryloxides according ...
4-Hydroxybenzoic acid, also known as p-hydroxybenzoic acid (PHBA), is a monohydroxybenzoic acid, a phenolic derivative of benzoic acid.It is a white crystalline solid that is slightly soluble in water and chloroform but more soluble in polar organic solvents such as alcohols and acetone. 4-Hydroxybenzoic acid is primarily known as the basis for the preparation of its esters, known as parabens ...
[23] [24] The aromatic amino acid phenylalanine, synthesized in the shikimic acid pathway, is the common precursor of phenol containing amino acids and phenolic compounds. In plants, the phenolic units are esterified or methylated and are submitted to conjugation , which means that the natural phenols are mostly found in the glycoside form ...