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

A technology of tetrafluorobenzoic acid and tetrafluorophthalic acid, which is applied in the preparation of halogenated hydrocarbons, chemical instruments and methods, organic chemistry and other directions, can solve problems such as high toxicity and environmental pollution, and achieves improved alkalinity and reduced reaction. Dangerousness, the effect of reducing the side reaction of fluorine atom substitution

Active Publication Date: 2017-11-10
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

[0008] The above-mentioned 1,2,3,4-tetrafluorobenzene preparation method needs to go through the decarboxylation reaction step, and all the prior art disclosures need to use high-boiling point organic amines such as tri-n-butylamine as the reaction medium, which has high toxicity and environmental pollution. question

Method used

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

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Experimental program
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Effect test

Embodiment 1

[0025] Add 300g of deionized water and 37.5g of 2,3,4,5-tetrafluorobenzoic acid into a 500mL intermittent autoclave, start stirring, and heat up to 240°C for 4 hours of decarboxylation reaction; after the decarboxylation reaction is completed, open the exhaust valve to relieve pressure , cooled to room temperature, after standing, the liquid-liquid layer was separated to obtain an organic phase and an aqueous phase, and the organic phase was rectified to obtain 14.5 g of 1,2,3,4-tetrafluorobenzene, and the purity of the product was 98.1% through HPLC analysis. The yield was 50.0%.

Embodiment 2

[0027] Add 300g of ammonia solution with an ammonia concentration of 0.5g / L and 42.8g of 2,3,4,5-tetrafluorobenzoic acid into a 500mL batch-type high-pressure reactor, start stirring, and heat up to 210°C for 5 hours of decarboxylation reaction; after the decarboxylation reaction is completed , open the exhaust valve to relieve the pressure, and 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, and the organic phase is rectified to obtain 1,2,3,4-four 25.3 g of fluorobenzene, the purity of the product analyzed by HPLC was 98.5%, and the yield was 76.4%.

Embodiment 3

[0029] Add 300g of ammonia solution with an ammonia concentration of 1g / L and 50.0g of 2,3,4,5-tetrafluorobenzoic acid into a 500mL intermittent high-pressure reactor, start stirring, and heat up to 220°C for 4.5 hours of decarboxylation reaction; after decarboxylation 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, and the organic phase is rectified to obtain 1,2,3,4-tetrafluoro 32.5 g of benzene, the purity of the product analyzed by HPLC was 98.5%, and the yield was 84.0%.

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Abstract

The invention discloses a process for preparing 1,2,3,4-tetrafluorobenzene by decarboxylation of 2,3,4,5-tetrafluorobenzoic acid in an ammonia-containing high-temperature liquid water medium at a reaction temperature of 210-260°C. 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 1,2,3,4-tetrafluorobenzene. Background technique [0002] 1,2,3,4-tetrafluorobenzene (1,2,3,4-Tetrafluorobenzene, CAS number: 551-62-2), molecular formula: C 6 h 2 f 4 , the structural formula is as follows, colorless transparent liquid, boiling point 95°C, flash point 20°C, relative density 1.4g / cm 3 (25°C), it can be used as an important intermediate for the synthesis of a new generation of quinolone antibiotics and some pesticides. [0003] [0004] The preparation method of 1,2,3,4-tetrafluorobenzene mainly contains the following three kinds: [0005] (1) Using 2,3,4-trifluoroaniline as raw material, diazotization reaction with nitrous acid, the product reacts with fluoboric acid to generate solid diazonium fluoborate, and Schiemann reaction of thermal decomposition of diazonium fluoborate 1,2,3,4-Tetrafluorobenzene is obtained; [0006] (2) Using ph...

Claims

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Application Information

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