36- 36-dialkyloxypyromellitic dianhydrides its preparation method and polyimides prepared from the same

摘要

PURPOSE: 3,6-dialkyloxypyromellitic dianhydrides, a preparation process thereof and polyimides produced therefrom are provided. The 3,6-dialkyloxypyromellitic dianhydrides are useful as a monomer for synthesis of polymers and polyimides having improved solubility in organic solvent. CONSTITUTION: 3,6-dialkyloxypyromellitic dianhydrides are represented by formula(1), wherein R is independently alkyl having 2 to 24 carbon numbers. Their preparing process comprises the steps of: (a) dissolving N,N'-bis(4-butylphenyl)-3,6-dihydroxypyromellitic diimide and alcohol(ROH) in an organic solvent, and Mitsunobu-reacting them under argon condition to prepare N,N'-bis(4-butylphenyl)-3,6-dialkyloxypyromellite diimide of formula(4); (b) hydrolysis of N,N'-bis(4-butylphenyl)-3,6-dialkyloxypyromellitic diimide of formula(5) to prepare 3,6-dialkyloxypyromellitic acid of formula(6); and (c) cyclodehydration of 3,6-dialkyloxypyromellitic acid of formula(6).