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The copolymers of 1-(acetylsalicylyloxy)ethyl methacrylate (HEMA-ASA) with methacrylicacid (MA) have been prepared and their hydrolysis in dioxane-H_2.O either in acdic or alkaline medium,at 60℃or 37℃have been investigated. It is found that the chief product of hydrolysis is alwaysaspirin with minor amount of salicylic acid. Due to its neighbouring group effect, the hydrolysisrate of (HEMA-ASA)-MA copolymer markedly depends on its composition and the pH value ofhydrolysis medium, i.e. the hydrolysis rate increases with increasing mole fraction of MA in the copoly-mer and pH value of hydrolysis medium.
The copolymers of 1- (acetylsalicylyloxy) ethyl methacrylate (HEMA-ASA) with methacrylic acid (MA) have been prepared and their hydrolysis in dioxane-H_2.O either in acdic or alkaline medium, at 60 ℃ or 37 ℃ have been investigated. is found that the chief product of hydrolysis is always aspirin with minor amount of salicylic acid. Due to its neighbor group effect, the hydrolysis rate of (HEMA-ASA) -MA copolymer markedly depends on its composition and the pH value ofhydrolysis medium, ie the hydrolysis rate increases with increasing mole fraction of MA in the copolymerization and pH value of hydrolysis medium.