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Novel efficient preparation process of 2, 3, 5, 6-tetrafluorobenzyl alcohol

A technology for the preparation of tetrafluorobenzyl alcohol, which is applied in the field of preparation of new high-efficiency 2,3,5,6-tetrafluorobenzyl alcohol, can solve the problems of easy explosion and fire, and achieve the goal of reducing pollution and strong cost advantages Effect

Active Publication Date: 2022-07-15
忠同科技(大连)有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In addition, when active metals are used to defluorinate pentafluorobenzyl alcohol, a large amount of active metals react with acid to produce hydrogen gas, which is prone to explosion and fire

Method used

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  • Novel efficient preparation process of 2, 3, 5, 6-tetrafluorobenzyl alcohol

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] 2000 g of 85% formic acid and 100 g of pentafluorobenzonitrile (0.518 mol) were added to a 3 L reaction kettle. Start stirring and add 539 g of sodium formate dihydrate. Heated to 50-60°C and added 6.3g of 5% Pd / C (dry basis); heated to 70-80°C and reacted for 5 hours. The end of the reaction was when the remaining starting material was less than 1.0%. Cool to 20-30°C and filter. The filtrate was pumped and concentrated under reduced pressure. Concentrate to dryness, add 500 g of water to the kettle and stir. The aqueous phase was extracted twice with 400 g of dichloromethane. Dichloromethane was recovered from the organic phase at atmospheric pressure, and 78.9 g of 2,3,5,6-tetrafluorobenzonitrile was obtained by distillation under reduced pressure, with a yield of 87% and a purity of 99.4%.

Embodiment 2

[0031] 2000 g of 85% formic acid and 100 g of pentafluorobenzonitrile (0.518 mol) were added to a 3 L reaction kettle. Start stirring and add 539 g of sodium formate dihydrate. Heat to 50-60°C and add 3.2g of 10% Pd / C (dry basis); raise the temperature to 70-80°C and react for 6 hours. The end of the reaction was when the remaining starting material was less than 1.0%. Cool to 20-30°C and filter. The filtrate was pumped and concentrated under reduced pressure. Concentrate to dryness, add 500 g of water to the kettle, and stir. The aqueous phase was extracted twice with 400 g of dichloromethane. Dichloromethane was recovered from the organic phase at atmospheric pressure, and 77.1 g of 2,3,5,6-tetrafluorobenzonitrile was obtained by distillation under reduced pressure, with a yield of 85% and a purity of 99.0%.

Embodiment 3

[0033]250 g of 2-methyltetrahydrofuran was added to the drying reaction kettle, and stirring was started. The ice water is cooled to 0-10°C and dry hydrogen chloride gas is introduced into it. Use wet pH test paper to test the bottle mouth, and stop the introduction of hydrogen chloride when the pH test paper turns red quickly. After adding 81.2 g of stannous dichloride (0.428 mol), it was stirred for 1 hour. 50 g of 2,3,5,6-tetrafluorobenzonitrile (0.2856 mol) was added in portions, and the reaction was incubated for 5 hours. The end of the reaction was when the remaining starting material was less than 1.0%. Add water to hydrolyze. The organic phase is washed with water. The 2-methyltetrahydrofuran was recovered from the organic phase under normal pressure, and then distilled under reduced pressure to obtain 48.2 g of 2,3,5,6-tetrafluorobenzaldehyde, with a purity of 98.3% and a yield of 94.7%.

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Abstract

The invention discloses a novel efficient preparation process of 2, 3, 5, 6-tetrafluorobenzyl alcohol, and belongs to the technical field of fine chemical engineering. Pentafluorobenzonitrile is subjected to Pd / C catalytic reaction in a 85% formic acid and sodium formate system to generate 2, 3, 5, 6-tetrafluorobenzonitrile, then stannous chloride Stephen is reduced to obtain 2, 3, 5, 6-tetrafluorobenzaldehyde, finally sodium borohydride / potassium borohydride is reduced to generate 2, 3, 5, 6-tetrafluorobenzyl alcohol, and the product purity is 99.5% or above. The preparation process of the 2, 3, 5, 6-tetrafluorobenzyl alcohol has the advantages of high yield, low cost, good safety and high product purity.

Description

technical field [0001] The invention relates to a preparation process of a novel and efficient 2,3,5,6-tetrafluorobenzyl alcohol, and belongs to the technical field of fine chemicals. Background technique [0002] 2,3,5,6-Tetrafluorobenzyl alcohol is a key intermediate in the preparation of transfluthrin. Transfluthrin is a broad-spectrum insecticide with extremely low acute and chronic toxicity. It is widely used in sanitary insecticidal products and is an environmentally friendly green pesticide. There are six main routes for the preparation of 2,3,5,6-tetrafluorobenzyl alcohol reported in the literature. [0003] Route 1: 2,3,5,6-tetrafluorobenzyl alcohol is prepared from dimethyl 2,3,5,6-tetrafluoroterephthalate as raw material. Dimethyl 2,3,5,6-tetrafluoroterephthalate is reduced by sodium borohydride in ethylene glycol dimethyl ether solvent, and the resulting off-white solid is hydrolyzed to obtain 2,3,5,6-tetrafluoro-p-hydroxyl Toluic acid (82.6% yield) and 2,3,5,...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C29/14C07C33/46
CPCC07C29/14C07C45/44C07C253/30C07C33/46C07C47/55C07C255/50Y02P20/584
Inventor 张同斌姜殿平王涛刘英亮
Owner 忠同科技(大连)有限公司
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