SU487883A1 - The method of obtaining unsubstituted diimides of tetracarboxylic aromatic acids - Google Patents

Description

one

The invention relates to an improved method for the preparation of unsubstituted tetracarboxylic aromatic acid dipmides, which are used as monomers for the synthesis of heat-resistant iolimides.

There is a known method for the production of pyromellitic diimpt acid by reacting the corresponding diahydride with an excess (more than 70%) of urea for 1.5 hours in acetic acid at the boiling point of the reaction mixture. The yield of unsubstituted pyromellite diimide is 75%.

In order to increase the yield of the target product and intensify the process in the proposed method, nitrobenzene is used as a solvent and the process is carried out at 195-220 ° C mainly at the stoichiometric ratio of the starting components. This allows you to increase the yield of the target product to 99% and reduce the reaction time by 4-9 times. In addition, urea consumption is reduced to a stoichiometric amount.

It should also be noted that, along with the known pyromellitic acid diimide, the proposed method makes it possible to obtain a number of new DYIMIDS of arolgatic tetracarboxylic acids, for example, 3.3, 4,4-tetracarboxydiphenyl oxide, 3, 3, 4, 4-tetracarboxydiphenylsulfone.

Example 1. Synthesis of 1 mellitic acid.

To a solution of 1.0 g pyromellitic dianhydride in 50 ml of nitrobenzene, heated to

195 ° C, and small portions of 0.28 g of urea are added, after which the reaction mass is maintained at 15 mip at 195 ° C. A white precipitate was separated from the cooled reaction mass, which was washed with a small

amount of N, N-dimethylformamide, ether and dried for 1 hour at a comed temperature and 1 hour at 100 ° C. Draft weight 0.9 g (90.8%). T. pl. (charring). The nitrogen content is 13.01% (theoretical 12.97%).

Example 2. Synthesis of diimide 3,3, 4,4-tetracarboxydithiyl oxide.

To a solution of 2 g of 3-DANAPRID, 4,4-tetracarboxydipheploxide in 20 ml of nitrobenzene at 215 ° C in small portions of 0.4 g

urea in leakage 4-10 mission. The reaction mass is maintained at 220 ° C for another 10 minutes. 1-1 3 of the cooled reaction mass, a precipitate is separated, which is washed with a small amount of .N, N-d-methyl-formamide and ether. After drying with air for 2-3 hours at 100 ° C (1 hour), the weight of the precipitate is 1.94 g (97.6%). The IR spectrum in petrolatum shows carboxylic imide absorption at 1768, 1715, absorption of ether ether sv1 311 1058, 1235, 1275 and absorption are grouped “N – H 3080, 3200 cm. T. Il. 364 - - 366 ° С. Nitrogen content is 9.07 (theoretical 9.09%). Example 3. Synthesis of dnnmnd 3,3, 4,4-tetr; 1 carboxymethyl sulfonate.

To a solution of 4 g of dianhydride 3,3, 4,4-diahydride of tetracarboxydiphenylsulfone in 10 ml of nitrobenzene at 210 ° C, 0.67 g of urea are added in small amounts to yurts. The resulting reaction mass is maintained at this temperature for 25 minutes. After cooling, 3.98 g of precipitate was recovered from the reaction mass. After washing with a small amount of Nf, N-dimethylformamide and ether, the product is dried for 1 h in air at room temperature for another 10 minutes at this temperature. The precipitate recovered after cooling is washed with a small amount of N, N-one-dimethylformamide, ether, and dried first with air at room temperature for 1 hour and at 100 ° C for 1 hour. The weight of the finished product is 3.96 g (99.4%). T. Il. 400-402C. The nitrogen content is 7.8% (theoretical 7.89%), sulfur 8.76% (theoretical 8.99%). IR spectrum in vaseline: carboxyl absorption 1710, 1725, and 1780, absorption of imide proton - 3100 and 3240 cm, absorption of sulfo group - 1120, 1310.

The results obtained are tabulated.