METHOD FOR PREPARING AMINOPHENOXYPHTHALIC ACIDS

FIELD: organic chemistry, chemical technology. ^ SUBSTANCE: invention relates to a new method for preparing aminophenoxyphthalic acids that are monomers of type AB used for preparing polyimides. Aminophenoxyphthalic acids of the general formula (I) are given in the invention description wherein Y means trivalent radical taken among radicals row of the general chemical structure (II) or (III) given in the invention description wherein R means hydrogen atom (H), oxyphenyl, N-morpholinyl radicals. Method for their preparing involves two stages: in the first stage method involves carrying out the process of interaction of nitrophthalonitrile of the general formula (IV) given in the invention description wherein R has above indicated values with 3- or 4-acetamidophenol of the general formula (V) given in the invention description in the presence of alkaline metal carbonate in amide solvent medium. Then as alkaline metal carbonate method involves using potassium carbonate mainly and dimethylformamide or dimethylacetamide aqueous solutions are used as an amide solvent. Alkaline hydrolysis is carried out in an aqueous-methanol potassium hydroxide (KOH) solution. Prepared aminophenoxyphthalic acid is isolated as a precipitate by acidification of the reaction mass with acetic acid mainly up to pH 4-5. Aminophenoxyphthalic acids are monomers used for synthesis of polyimides comprising at least one repeated link taken among links row of the general formula (VI) given in the invention description wherein Y has above indicated values. Invention provides preparing new aminophenoxyphthalic acids, for example, oxyphenyl- or N-morpholinyl-substituted acids. Applying these compounds allows expanding possibility for preparing polyimides having substitutes and comprising hinged fragments in the main chain, in particular, oxygen atoms that as one can expect must enhance the chain flexibility and therefore to promote appearance of thermoplasticity property. ^ EFFECT: improved preparing method, improved and valuable properties of compounds. ^ 5 cl, 1 sch, 6 ex