Hippuric acid 2207358 220709116 2008-06-21T05:00:56Z 76.87.81.54 /* Uses in medicine */ {{Chembox new | ImageFile = Hippuric acid.png | ImageSize = | IUPACName = Benzoylaminoacetic acid | OtherNames = Hippuric acid, N-benzoylglycine, benzoyl glycocoll, benzoyl amidoacetic acid | Section1 = {{Chembox Identifiers | CASNo = 495-69-2 | PubChem = | SMILES = O=C(O)CNC(C1=CC=CC=C1)=O }} | Section2 = {{Chembox Properties | Formula = C<sub>9</sub>H<sub>9</sub>NO<sub>3</sub> | MolarMass = 179.17 g/mol | Appearance = | Density = | MeltingPt = 187 - 188 &deg;C | BoilingPt = 240 &deg;C (dec.) | Solubility = }} | Section3 = {{Chembox Hazards | MainHazards = | FlashPt = | Autoignition = }} }} '''Hippuric acid''' ([[Greek language|Gr.]] ''hippos'', horse, ''ouron'', urine) is an [[organic acid]] found in the [[urine]] of [[horse]]s and other herbivores. High concentrations of hippuric acid can also indicate a [[Toluene (toxicology)|toluene intoxication]]. 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]]. [[Justus von Liebig]] showed in [[1829]] that hippuric acid differed from benzoic acid, and in 1839 determined its constitution, while in 1873 [[Victor Dessaignes]] synthesized it by the action of [[benzoyl chloride]] on the zinc salt of glycine.<ref>{{cite journal | title = Ueber die Regeneration der Hippursäure | author = Dessaignes V. | journal = Annalen der Chemie und Pharmacie | volume = 87 | issue = 3 | pages = 325–327 | year = 1853 | url = | doi = 10.1002/jlac.18530870311}}</ref> It is also formed by heating [[benzoic anhydride]] with glycine, <ref>{{cite journal | title = Synthese von Hippursäure und Hippursäureäthern | author = [[Theodor Curtius|Curtius T.]] | journal = Berichte der deutschen chemischen Gesellschaft | volume = 17 | issue = 2 | pages = 1662–1663 | year = 1884 | url = | doi = 10.1002/cber.18840170225}}</ref> and by heating [[benzamide]] with [[monochloroacetic acid]]. Hippuric acid crystallizes in [[rhombic]] prisms which are readily soluble in hot water, melt at 187 °C and decompose at about 240 °C. It is readily [[hydrolyse]]d by hot caustic [[alkali]]s to [[benzoic acid]] and glycine. [[Nitrous acid]] converts it into [[benzoyl glycolic acid]], C<sub>6</sub>H<sub>5</sub>C(=O)OCH<sub>2</sub>CO<sub>2</sub>H. Its ethyl [[ester]] reacts with [[hydrazine]] to form hippuryl hydrazine, C<sub>6</sub>H<sub>5</sub>CONHCH<sub>2</sub>CONHNH<sub>2</sub>, which was used by [[Theodor Curtius]] for the preparation of [[azoimide]]. == Uses in medicine == Para-amino-hippuric acid (PAH), a derivative of Hippuric Acid, is a compound useful in medical tests involving the kidney. PAH is completely filtered from [[Blood plasma|plasma]] at the [[glomerulus]] and not reabsorbed by the tubules, in a manner identical to [[inulin]]. PAH is different from inulin in that the fraction of PAH that bypasses the glomerulus and enters the nephron's tubular cells (via the [[Peritubular capillaries]]) is completely secreted. [[Clearance (medicine)|Renal Clearance]] of PAH is thus useful in calculation of renal plasma flow (RPF), which empirically is (1-[[Hematocrit]]) times [[renal blood flow]]. Of note, the clearance of PAH is reflective only of RPF to portions of the kidney that deal with urine formation, and thus underestimates actual RPF by about 10%. <ref>Costanzo, Linda. Physiology, 4th Edition. Philadelphia: Lippincott Williams and Wilkins, 2007. Page 156-160.</ref> ==References== <references/> *{{1911}} ==External links== [http://msds.chem.ox.ac.uk/HI/hippuric_acid.html Safety data] from the chemistry department at Oxford University. [[Category:Carboxylic acids]] [[Category:Amides]] [[de:Hippursäure]] [[es:Ácido hipúrico]] [[fr:Acide hippurique]] [[it:Acido ippurico]] [[hu:Hippursav]] [[ja:馬尿酸]] [[pl:Kwas hipurowy]] [[ru:Гиппуровая кислота]]