The structural unit; 5-ASA is part of numerous antimicrobial agents, colorectal cancer chemopreventive, antitumors, neuroprotective and anti-inflammatory. Since the discovery that 5-ASA is the active moiety of sulfasalazine (SASP) in the treatment of IBD; several new 5-ASA based drugs have been developed to improve its pharmacokinetic and pharmacodynamic properities. Chemically, 5-ASA has extremely low solubility in water (1 mg/ml at 20°C) and the saturated aqueous solution has a pH about 4.1. It’s easily oxidized and its stability in solution is influenced by temperature, light exposure and pH. The compound is expected to undergo oxidative degradation, because of its 4-aminophenol structure this may lead to stability problems in pharmaceutical preparations . The autooxidation of 5-ASA has been studied and it was found that 5-ASA is susceptible to autooxidative transformation resulting in polymeric species of 5-ASA, from which a trimeric species could be synthesized by oxidation of 5-ASA with hypochlorite anion. The instability of 5-ASA in biological samples has also been reported . It is significant to note that the N-acetyl derivative of 5-ASA is stable under conditions causing rapid decomposition of 5-ASA. This indicates that the amine function plays an essential role in 5-ASA degradation.