1H-Purine-2,6,8(3H)-trione,7,9-dihydro- (69-93-2)

 Uric acid (CAS NO.69-93-2),which also can be called for 1H-Purine-2,6,8(3H)-trione,7,9-dihydro- ; 1H-Purine-2,6,8(3H)-trione,7,9-dihydro- ; 1H-Purine-2,6,8-triol;2,6,8-Trioxopurine ; 6,8(3H)-Trione,7,9-dihydro-1H-Purine-2;7,9-Dihydro-1H-purine-2,6,8(3H)-trione ; 8(3H)-Trione,7,9-dihydro-1h-purine-6 ; Purine-3,6,8(1H,3H,9H)-trione .This chemical is a of-white crystals. It is a diprotic acid with pKa1=5.4 and pKa2=10.3. Thus in strong Alkali at high pH it forms the dually charged full Urate ion , but at biological pH or in the presence of Carbonic acid or Carbonate ions it forms the singly charged Hydrogen or Acid urate ion as its pKa2 is greater than the pKa1 of Carbonic acid . As its second ionization is so weak the full Urate salts tend to hydrolyse back to Hydrogen urate salts and free base at pH values around neutral. It is aromatic because of the Purine functional group.As a bicyclic, heterocyclic Purine derivative, It does not protonate in the same manner as do Carboxylic acids . X-Ray diffraction studies on the Hydrogen urate ion in crystals of Ammomium hydrogen urate , formed in vivo as gouty deposits, revealed that the Keto-oxygen in the 2 position of a tautomer of the Purine structure existed as a hydroxyl group and that the two flanking nitrogen atoms at the 1 and 3 positions shared the ionic charge in the six membered pi-resonance-stabilized ring.When heated to decomposition it emits toxic fumes of NOx .

Reported in EPA TSCA Inventory.