Technological method for preparing 2, 3, 4, 5-tetrachloride phthalic anhydride

A technology of tetrafluorobenzoic acid and tetrafluorophthalic acid, which is applied in two fields, can solve the problems of difficult process control, low product purity, and high production cost, and achieve the effects of low cost, improved reaction purity, and high competitive advantage

Inactive Publication Date: 2018-03-09
JIANGSU SHAXING CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0008] (3) In addition, there is also a method of using pentafluorobenzoic acid as a raw material to obtain the target product by selectively removing the fluorine at the ortho-position of the carboxyl group, but this me

Method used

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  • Technological method for preparing 2, 3, 4, 5-tetrachloride phthalic anhydride
  • Technological method for preparing 2, 3, 4, 5-tetrachloride phthalic anhydride
  • Technological method for preparing 2, 3, 4, 5-tetrachloride phthalic anhydride

Examples

Experimental program
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Embodiment 1

[0030] Step 1: Preparation of calcium 3,4,5,6-tetrafluorophthalate.

[0031] Add 24g of 3,4,5,6-tetrafluorophthalic acid, 200g of drinking water, and 25g of calcium chloride into a four-necked flask equipped with stirring, thermometer, and condenser, and raise the temperature to 50-55°C to dissolve all the solids , and kept stirring at this temperature for 3 hours. Then slowly add 20% ammonia solution dropwise until the pH gradually approaches neutrality. When the pH value reaches 6.0-7.0, stop the dropwise addition. After stirring at 50-55°C for 30 minutes, retest the pH and the reaction ends.

[0032] Step 2: Preparation of calcium 2,3,4,5-tetrafluorobenzoate.

[0033] Slowly lower the temperature of the above reaction solution to 5-10°C, solids will gradually precipitate out, keep stirring at this temperature for 2 hours, filter, wash with appropriate amount of cold water, and obtain 3,4,5,6-tetrafluorophthalate calcium wet material About 32g. Throw the solid back into a...

Embodiment 2

[0040] Step 1: Preparation of calcium 3,4,5,6-tetrafluorophthalate.

[0041] Put 24g of 3,4,5,6-tetrafluorophthalic acid, 200g of drinking water, and 35g of calcium chloride into a four-neck flask in turn, raise the temperature to 60-65°C to dissolve all the solids, and keep stirring at this temperature for 2 ~3 hours. Then slowly add 20% ammonia solution dropwise, and when the pH value reaches 6.0-7.0, stop the dropwise addition, and use about 88 g of deammonia water. After stirring at 60-65°C for 30 minutes, retest the pH and it remains unchanged.

[0042] Step 2: Preparation of calcium 2,3,4,5-tetrafluorobenzoate.

[0043]Cool the reaction solution to 5-10°C, solids gradually precipitate out, and keep stirring at this temperature for 2 hours, then filter, wash with appropriate amount of cold water, and obtain 3,4,5,6-tetrafluorophthalate calcium wet material of about 33.5 g. Put the solid wet material back into a four-necked flask, add about 250g of drinking water and 3...

Embodiment 3

[0050] Step 1: Preparation of calcium 3,4,5,6-tetrafluorophthalate.

[0051] Put 48g of 3,4,5,6-tetrafluorophthalic acid, 400g of drinking water, and 80g of calcium bromide into a four-neck flask successively, raise the temperature to 60-65°C to dissolve all the solids, and keep stirring at this temperature for 2 ~3 hours. Then slowly add 20% aqueous ammonia solution dropwise, and when the pH value reaches 6.0-7.0, stop the dropwise addition, and use about 175 g of 20% concentration ammonia water. After stirring at 60-65° C. for 30 minutes, retest the pH unchanged.

[0052] Step 2: Preparation of calcium 2,3,4,5-tetrafluorobenzoate.

[0053] Cool the reaction solution to 5-10°C, solids gradually precipitate out, and keep stirring at this temperature for 2 hours, then filter, wash with appropriate amount of cold water, and obtain 3,4,5,6-tetrafluorophthalate calcium wet material of about 65.8 g. Put the solid wet material back into a four-necked flask, add about 1000g of dr...

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Abstract

The invention relates to an improved technological method for preparing 2, 3, 4, 5-tetrachloride phthalic anhydride. The improved technological method includes bonding 3, 4, 5, 6-tetrafluorophthalic acid and calcium ions in water phases to generate 3, 4, 5, 6-calcium tetrafluorophthalic acid; filtering out solid, then removing single-molecule calcium carbonate in water environments under the catalytic effect of specific strong acid and strong alkali salts to generate 2, 3, 4, 5-tetrachloride phthalic anhydride; continuing to carry out reaction on the generated 2, 3, 4, 5-tetrachloride phthalicanhydride and calcium carbonate to generate corresponding salt and releasing carbon dioxide; regulating pH (potential of hydrogen) values of water phases after the reaction is completely carried out;cooling and filtering the generated 2, 3, 4, 5-tetrachloride phthalic anhydride to obtain final finished products. The 3, 4, 5, 6-tetrafluorophthalic acid is used as a starting material. The improvedtechnological method has the advantages that the improved technological method is high in decarboxylation reaction yield and suitable for industrialization production, organic solvents can be omitted, waste gas, wastewater and industrial residues are easy to treat, and the like.

Description

technical field [0001] The invention belongs to the field of synthesis of pharmaceutical intermediates, and relates to a process preparation method of 2,3,4,5-tetrafluorobenzoic acid. Background technique [0002] 2,3,4,5-Tetrafluorobenzoic acid is an important pharmaceutical intermediate, English name: 2,3,4,5-Tetrafluorobenzoic acid, molecular formula: C 7 h 2 f 4 o 2 , melting point: 85~87℃, colorless flaky crystal, CAS number: 1201-31-6, structural formula as follows: [0003] [0004] 2,3,4,5-Tetrafluorobenzoic acid is widely used in the preparation of medicines, especially in the preparation of the third-generation quinolone antibacterial drugs Levefloxacin, Fleroxacin, Lomefloxacin ), ruloxacin (Ruloxacin), sparfloxacin (Spsrfloxacin) and other drugs. In addition, it is also used in pesticides and liquid crystal preparation. [0005] At present, there are many reports on the synthesis of 2,3,4,5-tetrafluorobenzoic acid, the more typical ones are as follows: ...

Claims

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Application Information

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IPC IPC(8): C07C51/02C07C63/70
CPCC07C51/02C07C51/38C07C51/412C07C63/70C07C63/68
Inventor 王文斌
Owner JIANGSU SHAXING CHEM
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