METHOD OF OBTAINING DIANHYDRIDES OF AROMATIC TETRACARBONIC ACIDS Russian patent published in 2019 - IPC C07D311/92 C07D311/76 

FIELD: technological processes.

SUBSTANCE: proposed method for producing aromatic tetracarboxylic acid dianhydrides is carried out by condensation on C-C bonds in aromatic fragments of esters of aromatic halogenicarboxylic acids, preliminarily obtained by the reaction of the interaction of the corresponding aromatic halogenicarboxylic acid dianhydrides and lower monohydric alcohols, carried out at boiling in the presence of catalytic amounts of sulfuric acid, followed by isolation of the obtained products, moreover, the subsequent condensation reaction of esters of aromatic halocarboxylic acids is carried out in an atmosphere of inert gas, in an amide organic solvent in the presence of a catalytic mixture containing anhydrous nickel halide, triphenylphosphine and activated zinc powder, after which successive stages of processing the reaction mass are carried out: filtration, precipitation with water, boiling in the presence of an alkaline agent, cooling, washing and drying, where as the starting anhydrides of aromatic halo dicarboxylic acids are used compounds selected from the following group: 4-chloro-1,8-naphthalene dicarboxylic anhydride, 4-bromo-1,8-naphthalene dicarboxylic anhydride, 3-iodine-1-phthalic anhydride, 4-iodine-1-phthalic anhydride, which are converted to the corresponding esters by boiling with C₁-C₄ monohydric alcohol, taken in 5-7-fold excess by weight of equimolar amount for 8–16 hours, followed by evaporation of the alcohol, and complete dissolution of the dry residue in toluene, alkalinization with sodium hydroxide solution with stirring, separation of the organic layer, washing it, drying, evaporating the solvent and distilling the residue in a vacuum, after which a solution of the obtained aromatic halogenicarboxylic acid ester in a dry amide organic solvent is slowly introduced into a previously prepared catalytic mixture having a temperature of 80–100 °C and containing 0.03–0.07 moles of anhydrous nickel (II)halide, 0.2–0.4 mol of triphenylphosphine and 2–4 mol of activated zinc powder per 1 mol of aromatic halogenicarboxylic acid dianhydride, and the resulting reaction mass is stirred at 80–100 °C for 6–12 hours, after which the organic amide solvent is evaporated and a low-boiling chlorine-containing organic solvent is added to the remaining reaction mass, and then the resulting solution, while cooling and stirring, is added to an aqueous solution of hydrochloric acid, filtered, the organic layer is separated, the solvent is evaporated, and the residue is dissolved and the resulting aromatic tetracarboxylic acid dianhydride is dried in vacuum for 5–10 hours at 150–200 °C. Yield of final products is 21–49 %. Obtaining final products (dianhydride 2,2',3,3'-biphenyl tetracarboxylic acid, dianhydride 4,4'-binaftyl-1,1',8,8'-tetracarboxylic acid, dianhydride 4,4'-binaftyl-1,1',8,8'-tetracarboxylic acid, dianhydride 3,3',4,4'-biphenyl tetracarboxylic acid) confirmed by ¹H NMR and elemental CHNS analysis.

EFFECT: describes methods for producing aromatic tetracarboxylic acid dianhydrides with biphenyl or binaphthyl fragments, which can be used to obtain polyimide materials used in the manufacture of matrices for radiation-resistant composite materials used in various fields of technology.

6 cl, 5 ex