Method for preparing 3,4-difluorobenzonitrile

A technology for difluorobenzonitrile and difluorotoluene is applied in the field of preparing 3,4-difluorobenzonitrile, which can solve the problems of complicated post-processing, influence, long reaction time, etc., and achieves improved purity, simple preparation process and low cost Effect

Inactive Publication Date: 2019-01-11
郭健
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the reaction time of this method is longer, exceeding 20 hours, and side reactions such as dehalogenation and coking are serious, which affects the yield of 3,4 difluorobenzonitrile, and there are problems such as complicated post-treatment

Method used

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  • Method for preparing 3,4-difluorobenzonitrile
  • Method for preparing 3,4-difluorobenzonitrile
  • Method for preparing 3,4-difluorobenzonitrile

Examples

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Embodiment 1

[0031] The method for preparing 3,4-difluorobenzonitrile of the present embodiment comprises the following steps:

[0032] (1) Add 3,4-difluorotoluene and antimony pentachloride into the chlorination reaction kettle, turn on the light system, and heat up to 120°C, start to pass chlorine gas, and control the speed of chlorine flow, and at the same time, the The HCl gas is extracted under negative pressure. When the chlorination reaction is over, the chlorine gas is stopped and the heat preservation is continued for 1 hour;

[0033] (2) put the product of step (1) in the hydrolysis reaction kettle, steam heating, when the material temperature reaches 110 ℃, add zinc chloride and polar aprotic solvent, carry out hydrolysis reaction under the condition of rising temperature and reflux, then place In the desolvation kettle, under the vacuum degree of 0.06Mpa, pass steam and heat to 130°C to fractionate the polar aprotic solvent, and then obtain fluorinated benzaldehyde crystals aft...

Embodiment 2

[0047] The method for preparing 3,4-difluorobenzonitrile of the present embodiment comprises the following steps:

[0048] (1) Add 3,4-difluorotoluene and antimony pentachloride into the chlorination reaction kettle, turn on the light system, and heat up to 130°C, start to pass chlorine gas, and control the speed of chlorine flow, and at the same time, the The HCl gas is extracted under negative pressure. When the chlorination reaction is over, the chlorine gas is stopped and the heat preservation is continued for 2 hours;

[0049] (2) put the product of step (1) in the hydrolysis reaction kettle, steam heating, when the material temperature reaches 120 ℃, add zinc chloride and polar aprotic solvent, carry out hydrolysis reaction under the condition of reflux of raising temperature, then place In the desolvation kettle, under the vacuum degree of 0.1Mpa, pass steam and heat to 140°C to fractionate the polar aprotic solvent, and then obtain fluorinated benzaldehyde crystals aft...

Embodiment 3

[0063] The method for preparing 3,4-difluorobenzonitrile of the present embodiment comprises the following steps:

[0064] (1) Add 3,4-difluorotoluene and antimony pentachloride into the chlorination reaction kettle, turn on the light system, heat up to 15°C, start to pass chlorine gas, and control the speed of chlorine flow, and at the same time, The HCl gas is extracted under negative pressure. When the chlorination reaction is over, the chlorine gas is stopped and the heat preservation is continued for 1.5h;

[0065] (2) put the product of step (1) in the hydrolysis reaction kettle, steam heating, when the material temperature reaches 115 ℃, add zinc chloride and polar aprotic solvent, carry out the hydrolysis reaction under the reflux condition of raising temperature, then place In the desolvation kettle, under the vacuum degree of 0.08Mpa, pass steam and heat to 135°C to fractionate the polar aprotic solvent, and then obtain fluorinated benzaldehyde crystals after layerin...

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Abstract

The invention provides a method for preparing 3,4-difluorobenzonitrile. The method comprises the following steps: (1) adding 3,4-difluorotoluene and antimony pentachloride into a chlorination reactor,turning on an illumination system, introducing chlorine, and carrying out a chlorination reaction; (2) adding a product obtained in step (1) into a hydrolysis reactor, adding zinc chloride and a polar aprotic solvent, and carrying out a hydrolysis reaction under heating refluxing conditions to obtain fluorobenzaldehyde; (3) introducing the fluorobenzaldehyde obtained in step (2) into an oximationreactor, and carrying out an oximation reaction to obtain crystallized crude 3,4-difluorotoluene; and (4) recrystallizing and decolorizing the crude 3,4-difluorotoluene to obtain fine 3,4-difluorotoluene. The method has the advantages of mild reaction conditions, simple preparation process, high yield, high purity, multi-time reuse of reaction solvents, low cost, small emission of three wastes, and suitableness for industrial production.

Description

technical field [0001] The invention relates to the technical field of chemical intermediates, in particular to a method for preparing 3,4-difluorobenzonitrile. Background technique [0002] 3,4-difluorobenzonitrile can be used in the synthesis of pesticides, medicines and fluorine-containing liquid crystal display materials. The pesticide synthesized with it has strong selectivity, less usage, low toxicity to humans, and low residue. It is currently the safest rice herbicide, and it is a widely developed pesticide. Therefore, how to efficiently synthesize 3,4 difluorobenzene Nitrile has received enormous attention. [0003] Li Fugang et al. ("Pesticides" Volume 47, No. 3) reported a one-step synthesis method of 3,4-difluorobenzonitrile with ortho-difluorobenzene as raw material through bromination and cyanation reactions. Route as follows: [0004] [0005] The method takes 1-bromo-3,4-difluorobenzene as an intermediate, uses cuprous cyanide as a cyanide reagent, adds...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C253/00C07C255/51C07C45/43C07C47/55C07C17/14C07C25/13
CPCC07C253/00C07C17/14C07C45/43C07C255/51C07C47/55C07C25/13
Inventor 郭健
Owner 郭健
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