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Method for preparing 3,4,5,6-tetrafluorophthalic acid

A technology of tetrafluorophthalic acid and methyltetrafluorophthalimide, which is applied in the field of green and clean 3,4,5,6-tetrafluorophthalic acid preparation, can solve the problems of restricting application, High cost, difficult wastewater treatment and other problems, to achieve the effect of reducing production costs, improving product yield, and reducing environmental pressure

Inactive Publication Date: 2014-10-01
JIANGSU SHAXING CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, in the production process, a large amount of waste sulfuric acid aqueous solution with a concentration of about 50% will be produced, which is difficult to handle. Wastewater treatment is very difficult and costly, which restricts its application in industrial production.

Method used

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  • Method for preparing 3,4,5,6-tetrafluorophthalic acid
  • Method for preparing 3,4,5,6-tetrafluorophthalic acid
  • Method for preparing 3,4,5,6-tetrafluorophthalic acid

Examples

Experimental program
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Effect test

Embodiment 1

[0019] Add 100 kilograms of N-methyltetrafluorophthalimide, 300 kilograms of water, and 0.8 kilograms of p-toluenesulfonic acid in the hydrolysis autoclave, at a pressure of 0.4kg / cm 2 , hydrolyzed at a temperature of 102°C, cooled to about 10°C after passing the central control, stirred and crystallized for 2 hours, centrifuged in a centrifuge, and dried the filter cake to obtain 3,4,5,6-tetrafluorophthalic acid. The rate is 80.7%.

Embodiment 2

[0021] Add 100 kilograms of N-methyltetrafluorophthalimide, 220 kilograms of water, and 0.8 kilograms of p-toluenesulfonic acid in the hydrolysis autoclave, at a pressure of 2.0kg / cm 2 , hydrolyzed at a temperature of 125°C, cooled to about 10°C after passing the central control, stirred and crystallized for 2 hours, centrifuged in a centrifuge, and dried the filter cake to obtain 3,4,5,6-tetrafluorophthalic acid. The rate is 93.5%.

Embodiment 3

[0023] Add 100 kilograms of N-methyltetrafluorophthalimide, 200 kilograms of water, and 0.8 kilograms of p-toluenesulfonic acid in the hydrolysis autoclave, at a pressure of 3.2kg / cm 2 , hydrolyzed at a temperature of 145°C, cooled to about 10°C after passing the central control, stirred and crystallized for 2 hours, centrifuged in a centrifuge, and dried the filter cake to obtain 3,4,5,6-tetrafluorophthalic acid. The rate is 79.6%.

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Abstract

The invention provides a method for preparing a 3,4,5,6-tetrafluorophthalic acid. N-methyl tetrafluorophthalimide is subjected to catalytic hydrolysis by a catalyst to generate the 3,4,5,6-tetrafluorophthalic acid at the pressure of 0.5-3.0kg / cm<2> and the temperature of 106-140 DEG C. By adopting the technical scheme disclosed by the invention, waste sulfuric acid is avoided, the reacted by-product methylamine can be applied to recovering and preparing the raw material N-methyl tetrafluorophthalimide, the pressure to the environment is greatly relieved, and the production cost is also significantly reduced when the yield of the product is improved.

Description

technical field [0001] The invention belongs to the field of chemical synthesis, and in particular relates to a green and clean preparation method of 3,4,5,6-tetrafluorophthalic acid. Background technique [0002] 3,4,5,6-Tetrafluorophthalic acid is a key intermediate for the preparation of ofloxacin and other fluoroquinolone antibiotics. The structural formula and carbon numbers are as follows: [0003] [0004] As described in "A Preparation of 2,3,4,5-Tetrafluorobenzoyl Chloride" (CN102627553A), the synthesis method is N-methyltetrafluorophthalimide (1) in aqueous sulfuric acid 3,4,5,6-tetrafluorophthalic acid (2) is obtained by hydrolysis, and its chemical reaction equation is as follows: [0005] [0006] With this process, the supply of raw materials is guaranteed, the process conditions are relatively mild, and the yield is about 85%, which is more suitable for industrial production. However, in the production process, a large amount of waste sulfuric acid aqu...

Claims

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Application Information

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IPC IPC(8): C07C51/06C07C63/68C07C209/62C07C211/04
CPCC07C51/06C07C209/62C07C63/68C07C211/04
Inventor 王文斌
Owner JIANGSU SHAXING CHEM
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