Гиппуровой кислоты

Химические свойства

White crystalline powder

Использование

N-Benzoylglycine also known as Hippuric Acid is the glycine conjugate of benzoic acid commonly found in ruminant urine. It is synthesized in the liver and its production is greatly increased following consuption of benzoic acid. In itself it does not have a direct biological function, however p-hydroxy-hippurica acid can be used as an inhibitor of Ca2+ ATPase.

Подготовка

Preparation of Hippuric acid from Glycine.
Principle: The hydroxy and amino functions can be easily benzoylated using Benzoyl chloride in aqueous alkaline conditions. This reaction is known as Schotten-Baumann reaction.
Reaction:

Procedure: Dissolve 0.5 g of glycine in 5 ml of 10% NaOH solution in a 25 ml conical flask. Add 0.9 ml of benzoyl chloride in five portions to the solution. Stopper the flask and shake vigorously after each addition until all the benzoyl chloride is reacted. Transfer the solution to a beaker and add few grams of ice and add conc. HCl slowly with stirring until the solution is acidic to litmus paper. Filter the crystalline precipitate of the product on a Buchner funnel, wash with cold water and drain well. Place the solid in a conical flask with 10 ml CCl4 and boil gently for 10 min. Allow the mixture to cool slightly, filter under gentle suction and wash with 10-20 ml CCl4. Record the practical yield and re-crystallize it.
Re-crystallization: Dissolve the crude product from boiling water (5 ml), with addition of decolorizing charcoal if necessary, filter the hot solution and cool the filtrate. The crystals of the product separate out. Filter, dry and record the melting point and TLC [using Butanal : acetic acid: water (4 : 1 : 1) as solvent or CHCl3:methanol (9 : 1) or toluene].

Определение

ChEBI: An N-acylglycine in which the acyl group is specified as benzoyl.

Методы очистки

Crystallise the acid from boiling H2O. Dry it over P2O5. Also purify it by dissolving 135-140g in 2L of boiling H2O, filtering through a steam-heated funnel and allowing to crystallise at ~20o (yield 115-122g first crop, m 186-187o). [Ingersoll & Babcock Org Synth Coll Vol II 328 1943, Beilstein 9 225, I 100.]