Hydrolysis study of organic acid anhydrides by differential thermal analysis--II. Maleic anhydride and trimellitic anhydride.

Differential thermal analysis has been used to follow the hydrolysis of maleic anhydride (MA) and trimellitic anhydride (TMA). On exposure of MA to an atmosphere of 96 % relative humidity, maleic acid is produced, hydrolysis being complete in 21 hr at 22 degrees, but no hydrolysis occurs at a relative humidity of 50%. When exposed to an atmosphere of 96% relative humidity, TMA is quite stable for short periods, but hydrolyses slowly, the production of trimellitic acid being complete in 113 hr at 22 degrees.