SU175652A1 - METHOD OF OBTAINING POLYESTERS - Google Patents

Description

Heat-resistant polyesters are obtained by polycondensation of dicarboxylic acid chlorides with aromatic hydroxyl-containing compounds, for example 3,3-bis-4: hydroxyphenylphthalimide.

According to the present invention, in the synthesis of polyesters, as an aromatic hydroxyl-containing compound, hydroxybenzoic acid hydrazides, for example 3- and 4-hydroxybenzoic acid hydrazides, are used. New polyesters containing 1,3,4-oxadpazole cycles in the main chains of macromolecules possess enhanced heat resistance.

The proposed polyesters receive a two-step synthesis. In the first stage, in the interaction of hydrazides of hydroxybenzoic acids with the acid chlorides of dicarboxylic acids, polyether hydrazine of regular structure is obtained.

nHO-Ar-G-NH-NHj- - nCl-C-R-C-CI - IIII II

O00

-2pNS1 flr-C-NH-NH-C-R-C-oTn L 11IIII -1II

O00

Hexamethylphosphoramide or dimethylformamide using, in the latter case, triethylamine or pyridine to bind the released hydrogen chloride, as well as the interfacial polycondensation method.

| Ar-C - NH-NH-C-R-C-ot ,, -pN, L IIIIII J П 1.

II Oh

N - N

Mr. IIil-,

| AG-S s-to-s-o | - "

L / II J G

Example 1. 1.52 g of 4-hydroxybenzoic acid hydrazide is dissolved in 20 ml of hexamethylphosphoramide and the solution is placed in a reaction flask equipped with a stirrer, an inlet and a outlet for nitrogen. When moving under a stream of nitrogen, a solution of 2.03 g of terephthalic acid chloride and 10 ml of hexamethylphosphoramide is added. Reaction mass

stirred under nitrogen flow for 8 hours, after which the polymer is planted in water. The resulting polyetherhydrazide from / filtered, washed with methanol and acetone and dried in vacuum at 60 ° C for

The resulting polymer — a white powdery substance — dissolves well in dimethyl sulfoxide and partly in dimethylformamide. The logarithmic viscosity of a 0.5o / about-th polymer solution in dimethyl sulfoxide is 0.2.

The polymer is stirred in a condensation tube and heated under vacuum at 2 mm Hg. Art. up to 280 ° C for 20 hours. In this case, polyether is obtained in quantitative yield, containing 1,3,4-oxadiazole cycles in the main chains of the macromolecules. The polyester does not dissolve in organic solvents and dissolves with decomposition in sulfuric acid. The polymer is thermally stable up to 410 ° C.

Example 2. 1.52 g of 3-hydroxybenzoic acid hydrazide is dissolved in 30 ml of dimethylformamide and the solution is placed in a three-neck reaction flask equipped with a blender and tubes for introducing and discharging nitrogen. To the solution was added 3 ml of triethylamine. Under stirring under a stream of nitrogen, a solution of 2.03 g of isophthalic acid chloride and 20 ml of dimethylformamide is added dropwise. The reaction mixture is stirred under a stream of nitrogen for 8 hours. The polyetherhydrazide is planted in water or methanol. The resulting polymer — a white powder — dissolves well in dimethyl sulfoxide, hexamethylphosphoramide and dimethylformamide. The viscosity of a 0.5o / o-th solution in dimethyl sulfoxide is 0.21. Output 840/0.

The polymer obtained is subjected to thermal cyclodehydration in a vacuum of 2 mm Hg. Art. at 230 ° C for 15 hours. The polyester is soluble with decomposition in sulfuric acid and thermally stable up to 300 ° C.

Example 3. To a basic solution of 1.52 g of 4-hydroxybenzoic acid hydrazide in water, with vigorous stirring, a solution of 2.03 g of terephthalic acid chloride in benzene was added. Intensive stirring of the reaction mass is continued for 30 minutes. Thereafter, the powdered white polyetherhydrazide is filtered and washed successively with water and methanol. The yield of the dried polymer is 87 ° / o. The logarithmic viscosity of a 0.5o / about-th polymer solution in dimethylsulfoxide is 0.4.

The thermal cyclodehydrate polymer is carried out under the conditions given in Example L

Subject invention

A method of producing polyesters by polycondensation of aromatic dicarboxylic acid chlorides with aromatic hydroxyl-containing compounds, characterized in that, in order to expand the range of heat-resistant polymers, oxazone-benzoic acid hydrazides, for example, 3- and 4-hydroxy hydrazides, are used as aromatic hydroxyl-containing compounds;