Hippuric acid

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Hippuric acid
Structural formula of hippuric acid
Ball-and-stick model of the hippuric acid molecule
Names
IUPAC name
Benzoylaminoethanoic acid
Other names
Hippuric acid, N-benzoylglycine, benzoyl glycocoll, benzoyl amidoacetic acid
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.007.098
KEGG
UNII
Properties
C9H9NO3
Molar mass 179.17 g/mol
Density 1,371 g/cm3
Melting point 187 to 188 °C (369 to 370 °F; 460 to 461 K)
Boiling point 240 °C (464 °F; 513 K) (decomposes)
Hazards
Safety data sheet Material Safety Data Sheet
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Hippuric acid (Gr. hippos, horse, ouron, urine) is a carboxylic acid found in the urine of horses and other herbivores. Hippuric acid crystallizes in rhombic prisms which are readily soluble in hot water, melt at 187 °C, and decompose at about 240 °C. High concentrations of hippuric acid may also indicate a toluene intoxication; however, scientists have called this correlation into question because there are other variables that influence levels of hippuric acid.[1] When many aromatic compounds such as benzoic acid and toluene are taken internally, they are converted to hippuric acid by reaction with the amino acid, glycine.

Synthesis[edit]

A modern synthesis of hippuric acid involves the acylation of glycine with benzoyl chloride:[2]

Preparation of hippuric acid.png

Reactions[edit]

Hippuric acid is readily hydrolysed by hot caustic alkalis to benzoic acid and glycine. Nitrous acid converts it into benzoyl glycolic acid, C6H5C(=O)OCH2CO2H. Its ethyl ester reacts with hydrazine to form hippuryl hydrazine, C6H5CONHCH2CONHNH2, which was used by Theodor Curtius for the preparation of hydrazoic acid.

History[edit]

Justus von Liebig showed in 1829 that hippuric acid differed from benzoic acid,[3] and in 1834 determined its constitution,[4] while in 1853 French chemist Victor Dessaignes (1800–1885) synthesized it by the action of benzoyl chloride on the zinc salt of glycine.[5] It was also formed by heating benzoic anhydride with glycine,[6] and by heating benzamide with monochloroacetic acid.

See also[edit]

References[edit]

  1. ^ Pero, RW (2010). "Health consequences of catabolic synthesis of hippuric acid in humans". Current clinical pharmacology. 5 (1): 67–73. PMID 19891605. doi:10.2174/157488410790410588. 
  2. ^ A. W. Ingersoll and S. H. Babcock. "Hippuric acid". Org. Synth. ; Coll. Vol., 2, p. 0328 
  3. ^ Liebig, Justus (1829) "Ueber die Säure, welche in dem Harn der grasfressenden vierfüssigen Thiere enthalten ist" (On the acid which is contained in the urine of grass-eating, four-footed animals), Annalen der Physik und Chemie, 17 : 389–399.
  4. ^ Liebig, Justus (1834) "Ueber die Zusammensetzung der Hippursäure" (On the composition of hippuric acid), Annalen der Physik und Chemie, 32 : 573–574.
  5. ^ Dessaignes V. (1853). "Ueber die Regeneration der Hippursäure" [On the regeneration of hippuric acid]. Annalen der Chemie und Pharmacie. 87 (3): 325–327. doi:10.1002/jlac.18530870311.  See also: Dessaignes (1853) "Note sur la régénération de l'acide hipparique," Comptes rendus, 37 : 251–252.
  6. ^ Curtius T. (1884). "Synthese von Hippursäure und Hippursäureäthern" [Synthesis of hippuric acid and hippuric acid esters]. Berichte der deutschen chemischen Gesellschaft. 17 (2): 1662–1663. doi:10.1002/cber.18840170225.