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Method for preparing dihydroxy phthalic acid

A technology of dihydroxyphthalic acid and hydroxyphthalic acid, which is applied in the field of polymer monomer preparation, can solve the problems of low yield and high pressure, and achieve the effects of short reaction time, mild reaction conditions and low cost

Active Publication Date: 2010-04-14
HARBIN INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0009] The present invention provides a method for preparing dihydroxyphthalic acid in order to solve the problems of high pressure and low yield in the current method for preparing dihydroxyphthalic acid

Method used

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  • Method for preparing dihydroxy phthalic acid
  • Method for preparing dihydroxy phthalic acid
  • Method for preparing dihydroxy phthalic acid

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Experimental program
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specific Embodiment approach 1

[0016] Specific embodiment one: the preparation method step of dihydroxyphthalic acid in the present embodiment is as follows: one, add iodine and iodine salt in the mixed solution of cyclohexanedione dicarboxylic acid diester and polar solvent, iodine accounts for cyclohexane di 1-10% of the mass of ketone dicarboxylic acid diester, and iodine salt accounts for 1-10% of the mass of cyclohexanedione dicarboxylic acid diester. After reacting for 30-40 minutes, at a temperature of 80-100°C, press the oxidant and The molar ratio of cyclohexanedione dicarboxylic acid diester is 1: 0.5-3, adding an oxidizing agent, reacting for 3-6 hours, then cooling to room temperature, filtering, and washing with deionized water three to five times. The product is mixed with water at a mass ratio of 1: 2 to 3, and the product molar ratio of the strong base to step 1 is 1: 2 to 4. Add a strong base in the N 2 Stir and heat to 90-100°C under protected conditions, then lower the temperature to room...

specific Embodiment approach 2

[0026] Specific embodiment 2: The difference between this embodiment and specific embodiment 1 is that after the oxidizing agent is added in step 1 and the reaction is completed, first add 50-80°C hot water with a volume of 1 / 6-1 / 4 of the polar solvent, and then add polar solvent Cold water at 1-10°C with 1 / 6-1 / 4 volume of the solvent used. Others are the same as in the first embodiment.

specific Embodiment approach 3

[0027] Specific embodiment 3: The difference between this embodiment and specific embodiment 1 is that after step 1, the product is vacuum-dried at 50-80°C for 20-24 hours to obtain light yellow solid powder, namely dihydroxyterephthalic acid diester (DDTA), the productive rate is above 94%. Others are the same as in the first embodiment.

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Abstract

Provided is a preparation method of dihydroxyphthalic acid, which relates to a preparation method of poly(2, 5-dihydroxy-1, 4-pyridobisimidazole) monomer. The invention solves the problem in the priorart, such as large required pressure and low yield. The invention comprises steps of: adding iodine and iodized salt in mixture liquid of cyclohexanedione phthalate and polarity solvent, reducing thetemperature after temperature insulation, adding an oxidant, and then orderly adding heat water and cold water, cooling to the room temperature, filtering, and water washing; dissolving the productsin water, adding strong alkali, mixing and heating under protection of N2, reducing the temperature to the room temperature, adding strong acid and reducing the temperature to the room temperature again,filtering, water washing, recrystallizing by mixed solvent, filtering and drying. The invention can perform reaction under atmospheric pressure, dihydroxyphthalic acid prepared in the invention has t he yield of 90%, and purity more than 99% after high efficiency liquid chromatography analysis, and can be stably storaged more than three month in a sealed dryer.

Description

technical field [0001] The invention relates to a preparation method of poly(2,5-dihydroxy-1,4-phenylenepyridodiimidazole) monomer. Background technique [0002] Dihydroxyphthalic acid belongs to hydroxy acid molecules, in which 2,5-dihydroxyterephthalic acid (DHTA) is the monomer for preparing poly(2,5-dihydroxy-1,4-phenylenepyridodiimidazole) , is the starting material for the preparation of various colorants, drugs and fluorescent substances. At present, there is no commercial product of DHTA, so it is quite necessary to choose a green and practical process route to prepare high-purity DHTA. The structural formula of DHTA is as follows: [0003] [0004] The method for preparing dihydroxyphthalic acid in the prior art is as table 1: [0005] Table 1 [0006] [0007] [0008] European Patent No. 298,289,370,389, and No. 548,906. Reported synthetic methods of hydroxyacids mention the preparation of DHTA in a strongly alkaline medium by Kolbe-Schmitt reaction i...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C65/03C07C51/353
Inventor 黄玉东林宏王峰宋元军王艳红
Owner HARBIN INST OF TECH