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Preparation method of 1,2,3,4-tetrafluorobenzene from 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, etc. Alkaline, promoting ionization effect

Active Publication Date: 2016-02-17
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

[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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  • Preparation method of 1,2,3,4-tetrafluorobenzene from 2,3,4,5-tetrafluorobenzoic acid
  • Preparation method of 1,2,3,4-tetrafluorobenzene from 2,3,4,5-tetrafluorobenzoic acid

Examples

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 preparation method of 1,2,3,4-tetrafluorobenzene from 2,3,4,5-tetrafluorobenzoic acid through decarboxylation reaction in a high temperature ammonia-containing liquid state aqueous medium at 210-260 DEG C. The preparation method has the advantages of high reaction rate, short decarboxylation reaction time, high yield, and green 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 Applications(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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