Process for preparing 3,3',4,4'-tetracarboxydiphthalic ether dianhydride
A technology of tetracarboxylic dianhydride and diphenyl ether, applied in 3 fields, can solve the problems of poor process stability, long process, difficulty in adding potassium carbonate and the like
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specific Embodiment approach 1
[0010] Specific embodiment one: this embodiment prepares 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride according to the following method: A, salt-forming reaction: add potassium hydroxide or sodium hydroxide in the reaction kettle, Make an aqueous solution with a mass concentration greater than 40%, control the reaction temperature of the solution at 60-120°C under stirring, add 4-halogenated phthalic anhydride to generate the corresponding potassium or sodium salt of 4-halogenated phthalate, and control the 4- The amount of halogenated phthalic anhydride and potassium hydroxide or sodium hydroxide is 2:1, and the pH value is about 7-10; after the reaction is completed, dehydrate under reduced pressure, and then vacuum-dry to make the water content lower than 1.0 % or less, the potassium salt or sodium salt of 4-halogenated phthalate is obtained, and the yield reaches more than 95%;
[0011] B. Condensation reaction: Add the above-mentioned obtained product 4-halogenate...
specific Embodiment approach 2
[0024] Specific embodiment two: This embodiment prepares 4-chlorophthalic acid potassium salt according to the following method: add 50wt.% KOH aqueous solution 100g in a 250ml three-necked bottle, add 4-chlorophthalic anhydride under heating and stirring, and control The reaction temperature is 60-100°C, and the pH value is adjusted at 7-10. After the reaction, dehydrate under reduced pressure, and then vacuum-dry to keep the water content below 1.0%, that is, 4-chlorophthalic acid Potassium salt, its yield reaches 98%.
specific Embodiment approach 3
[0025] Embodiment 3: This embodiment is different from Embodiment 2 in that KOH is replaced by NaOH, and the yield of the obtained 4-chlorophthalic acid sodium salt is 86.5%.
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