A method for preparing 2,3,4,5-tetrafluorobenzoic acid and 1,2,3,4-tetrafluorobenzene

A technology of tetrafluorobenzoic acid and tetrafluorophthalic acid, which is applied in chemical instruments and methods, preparation of halogenated hydrocarbons, organic chemistry, etc., can solve problems such as high toxicity and environmental pollution, and achieve improved alkalinity and reduced reaction Hazard, effect of promoting ionization

Active Publication Date: 2018-04-17
中化蓝天氟材料有限公司 +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0013] The above-mentioned 2,3,4,5-tetrafluorobenzoic acid and 1,2,3,4-tetrafluorobenzene preparation methods all need to go through the decarboxylation reaction step, and all need to use high-boiling point organic amines such as tri-normal Butylamine is used as a reaction medium, and there are problems such as high toxicity and environmental pollution

Method used

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  • A method for preparing 2,3,4,5-tetrafluorobenzoic acid and 1,2,3,4-tetrafluorobenzene
  • A method for preparing 2,3,4,5-tetrafluorobenzoic acid and 1,2,3,4-tetrafluorobenzene

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Embodiment 1

[0030] Add 300g of deionized water and 37.5g of tetrafluorophthalic acid into a 500mL intermittent high-pressure reactor, start stirring, and heat up to 230°C for decarboxylation for 150min; after the decarboxylation reaction is completed, open the exhaust valve to relieve pressure, cool to room temperature, and After the liquid-liquid separation, the organic phase and the aqueous phase are obtained; the aqueous phase is adjusted to pH 3-4, crystallized, and filtered to obtain crude 2,3,4,5-tetrafluorobenzoic acid; crude 2,3,4,5- Tetrafluorobenzoic acid was decolorized by active carbon, secondary crystallization, and vacuum-dried to obtain 15.4g 2,3,4,5-tetrafluorobenzoic acid product, and the product was analyzed by HPLC with a purity of 98.1% and a yield of 50.4%; After rectification, 5.2 g of 1,2,3,4-tetrafluorobenzene was obtained. The purity of the product analyzed by HPLC was 98.5%, and the yield was 22.0%.

Embodiment 2

[0032] Add 300g of ammonia solution with an ammonia concentration of 4g / L and 100.0g of tetrafluorophthalic acid into a 500mL intermittent high-pressure reactor, start stirring, and heat up to 230°C for 45 minutes for decarboxylation; after the decarboxylation reaction is completed, open the exhaust valve to relieve the pressure , recover the ammonia in the kettle; cool down to room temperature, and after standing still, the liquid-liquid layer is separated to obtain an organic phase and an aqueous phase; the aqueous phase is adjusted to a pH of 3 to 4, crystallized, and filtered to obtain crude 2,3,4,5-tetra Fluorobenzoic acid; crude 2,3,4,5-tetrafluorobenzoic acid was decolorized by activated carbon, secondary crystallized, and vacuum dried to obtain 19.3g of 2,3,4,5-tetrafluorobenzoic acid product, the product was analyzed by HPLC for purity 99.0% and a yield of 23.7%; the organic phase was rectified to obtain 43.2 g of 1,2,3,4-tetrafluorobenzene, and the product was analyze...

Embodiment 3

[0034] Add 300g of ammonia solution with an ammonia concentration of 2g / L and 60.0g of tetrafluorophthalic acid in a 500mL intermittent high-pressure reactor, start stirring, and heat up to 230°C for 60 minutes for decarboxylation; after the decarboxylation reaction is completed, open the exhaust valve to relieve pressure , recover the ammonia in the kettle; cool down to room temperature, and after standing still, the liquid-liquid layer is separated to obtain an organic phase and an aqueous phase; the aqueous phase is adjusted to a pH of 3 to 4, crystallized, and filtered to obtain crude 2,3,4,5-tetra Fluorobenzoic acid; crude 2,3,4,5-tetrafluorobenzoic acid was decolorized by activated carbon, secondary crystallized, and vacuum dried to obtain 13.0g of 2,3,4,5-tetrafluorobenzoic acid product, and the purity of the product was analyzed by HPLC 98.9% and a yield of 26.6%; the organic phase was rectified to obtain 25.8 g of 1,2,3,4-tetrafluorobenzene, and the product was analyze...

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Abstract

The invention discloses that 2,3,4,5-tetrafluorobenzoic acid and 1,2,3 ,4‑tetrafluorobenzene method. The method has high decarboxylation reaction rate, short decarboxylation reaction time, high yield and environmental protection.

Description

technical field [0001] The invention belongs to the field of fine chemicals and relates to a method for preparing 2,3,4,5-tetrafluorobenzoic acid and 1,2,3,4-tetrafluorobenzene. Background technique [0002] 2,3,4,5-tetrafluorobenzoic acid (2,3,4,5-Tetrafluorobenzoic acid, CAS number: 1201-31-6), molecular formula: C 7 h 2 f 4 o 2 , the structural formula is as follows, white crystal, melting point 85-87 ° C, is an intermediate in organic synthesis, pharmaceutical synthesis, liquid crystal, pesticides, etc., mainly used in the synthesis of fluoroquinolone antibacterial drugs. [0003] [0004] In the prior art, the preparation method of 2,3,4,5-tetrafluorobenzoic acid mainly contains following two kinds: [0005] (1) Using phthalic anhydride as starting material, first obtain 3,4,5,6-tetrachlorophthalic anhydride through chlorination reaction, then condense with aniline to obtain imine compound in the presence of acetic acid, and then In the presence of DMF, potassiu...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C17/363C07C25/13
Inventor 傅杰莫静吕秀阳徐卫国
Owner 中化蓝天氟材料有限公司
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