Process for preparing 3,4-difluoro-benzotrifluoride

A technology of difluorotrifluorotoluene and fluorotrifluorotoluene, which is applied in the preparation of halogenated hydrocarbons, halogen substitution preparation, chemical instruments and methods, etc. Affect the decomposition yield and other problems, and achieve the effects of easy industrial production, short reaction time, and simple preparation process

Inactive Publication Date: 2007-07-11
天津均凯农业科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The fluoroborate generated after diazotization by this method is difficult to dry thoroughly, which greatly affects the decomposition yield and brings certain difficulties to post-processing; another method is to carry out diazotization in hydrofluoric acid reaction, and then heated up to decompose to obtain 3,4-difluorobenzotrifluoride
Although this method improves the yield and reduces the production cost, it is only suitable for the production of large-tonnage products due to the high toxicity of hydrofluoric acid, which requires high equipment and good sealing.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0010] Add 3-nitro-4-chlorobenzotrifluoride (90.2g, 0.4mol), anhydrous potassium fluoride (34.8g, 0.6mol) and dry N,N-dimethylformamide (250ml) in the reaction flask , heated to 150° C. for 5 hours, filtered to remove the salt in the system, removed and rectified under reduced pressure to obtain 3-nitro-4-fluorobenzotrifluoride (76.9 g, 92%).

Embodiment 2

[0012] Add 3-nitro-4-chlorobenzotrifluoride (90.2g, 0.4mol), anhydrous potassium fluoride (34.8g, 0.6mol) and dry dimethyl sulfoxide (250ml) in the reaction flask, and heat up to 180 °C for 3 hours, filtered to remove the salt in the system, and rectified to obtain 3-nitro-4-fluorobenzotrifluoride (77.2 g, 92.4%).

Embodiment 3

[0014] Add 3-nitro-4-fluorobenzotrifluoride (42.8g, 0.2mol), tetramethylammonium fluoride (37.2g, 0.4mol) and dry tetrahydrofuran (150ml) into the reaction flask, and react at 30°C for 3 hours , concentrated at normal pressure to remove tetrahydrofuran, poured the residue into water, extracted with ethyl acetate, obtained 3,4-difluorobenzotrifluoride (32.4 g, 89%) by rectifying the organic phase under normal pressure.

[0015] Example 3

[0016] Add 3-nitro-4-fluorobenzotrifluoride (42.8g, 0.2mol), tetrabutylammonium fluoride (110.2g, 0.4mol) and dry tetrahydrofuran (250ml) into the reaction flask, and react at 30°C for 2.5 hours , concentrated at normal pressure to remove tetrahydrofuran, poured the residue into water, extracted with ethyl acetate, obtained 3,4-difluorobenzotrifluoride (30.9 g, 85%) by rectifying under normal pressure.

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PUM

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Abstract

The invention discloses a making method of 3, 4-difluo-trifluoro toluene, which comprises the following steps: adding 3-nitro-4-chloride trifluoro toluene and anhydrous potassium fluoride with molar rate at 11. 5-4 in the N, N-dimethyl formamide, dimethyl sulfoxide, N-methyl pyrrolidone, dimethyl sulphone or N, N-dimethyl acetyl solvent; stirring under 120-180 deg. c; filtering to remove inorganics; decompressing; rectifying; obtaining 3-nitro-4-chloride trifluoro toluene; adding 3-nitro-4-chloride trifluoro toluene and ammonium fluoride tetramethyl, ammonium fluoride tetraethyl, ammonium fluoride tetrapropyl or ammonium fluoride tetrabutyl with molar rate at 12-6 in the tetrahydrofuran, dioxi-hexacyclic ring or N, N-dimethyl formamide solvent; stirring under 25-110 deg. c; rectifying to obtain the product.

Description

technical field [0001] The invention relates to a preparation method of 3,4-difluorobenzotrifluoride, which belongs to the preparation technology of 3,4-difluorobenzotrifluoride. Background technique [0002] 3,4-Difluorotrifluorotoluene is an important pharmaceutical and pesticide intermediate. Examples of its known preparation methods include: One method is obtained by diazotization fluorination using the corresponding amino group. For example, in US Patent No. 4163661, p-chlorobenzotrifluoride is used as the starting material, and 3-amino-4-fluorobenzotrifluoride is generated by nitration, fluorine-chloride replacement, and nitro reduction, and then the corresponding product is obtained by diazotization and fluorination. The fluoroborate generated after diazotization by this method is difficult to dry thoroughly, which greatly affects the decomposition yield and brings certain difficulties to post-processing; another method is to carry out diazotization in hydrofluoric a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C17/093C07C17/20C07C25/13
Inventor 褚吉成李巍
Owner 天津均凯农业科技有限公司
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