METHOD OF PRODUCING DIANHYDRIDE OF 3,3-BIS-(3,4-DICARBOXYPHENYL) PHTHALIDE Russian patent published in 2019 - IPC C07D407/14 

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing dianhydrides of aromatic tetracarboxylic acids, namely dianhydride of 3,3-bis-(3,4-dicarboxyphenyl)phthalide, which is carried out by oxidation of 3,3-bis-(3,4-dimethylphenyl)phthalide with 20–25 % aqueous solution of nitric acid using 12–18 mol of nitric acid per 1 mole of 3,3-bis-(3,4-dimethylphenyl)phthalide and at temperature of 180–200 °C for 30–90 minutes under pressure of 18–25 atm, after which reaction mass is cooled to temperature of 60–70 °C with setting of atmospheric pressure, then performing partial evaporation of obtained solution and cooling it to 3–6 °C for 3–8 hours, then filtering obtained 3,3-bis-(3,4-dicarboxyphenyl)phthalide and its subsequent stepwise drying: first in vacuum at 1–10 mm Hg. and at temperature of 80–100 °C for 6–8 hours and then further raising temperature to 200–230 °C and holding at this temperature for 3–5 hours with subsequent extraction of end product.

EFFECT: technical result is a novel method of producing dianhydride of 3,3-bis-(3,4-dicarboxyphenyl)phthalide, which can be used to produce polyimides and composites used in microelectronics, as well as a curing agent for epoxy and alkyd resins.

1 cl, 9 ex