Hippuric acid

Levels of hippuric acid rise with the consumption of phenolic compounds (such as in fruit juice, tea and wine).

[1] Hippuric acid crystallizes in rhombic prisms which are readily soluble in hot water, melt at 187 °C, and decompose at about 240 °C.

A modern synthesis of hippuric acid involves the acylation of glycine with benzoyl chloride ("Schotten–Baumann reaction").

Alternatively, under certain conditions, phenylpyruvic acid may undergo a redox mechanism, such as Iron(II) donating an electron, to directly release carbon dioxide, followed by carbon monoxide, for the formation of a stable toluene radical which is resolved by an antioxidant such as ascorbate.

[2] Justus von Liebig showed in 1829 that hippuric acid differed from benzoic acid and he named it,[10] and in 1834 he determined its constitution,[11] while in 1853 French chemist Victor Dessaignes (1800–1885) synthesized it by the action of benzoyl chloride on the zinc salt of glycine.

Structural formula of hippuric acid
Recrystallised hippuric acid