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Preparation method of dicamba

A technology for dicamba and methanol, which is applied in the field of preparation of dicamba, can solve problems such as the monopoly of synthetic routes and production technology, and achieve the effects of high yield, cheap and easily available reagents, and simple operation.

Active Publication Date: 2019-01-04
JIANGSU CHANGQING AGROCHEMICAL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The market demand for dicamba is huge, but its synthesis route and production technology are monopolized by foreign manufacturers. At present, there are few domestic manufacturers of the original drug, so it is of great significance to study its new synthesis method and process conditions

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] Add 19.1 g of 2,5-dichlorobenzoic acid (0.1 mol) and 100 ml of methanol into the reaction flask, add a catalytic amount of acid, and reflux at 65~70 °C for 8 hours. After the reaction is over, distill under reduced pressure to remove excess methanol to obtain 19.5 g of methyl 2,5-dichlorobenzoate with a yield of 95%. Add the obtained methyl 2,5-dichlorobenzoate (0.095 mol) into the reaction flask, add 18.2 g of bromine (0.11 mol) and 2.5 g of aluminum tribromide, and react at 50 °C for 6 hours. After the reaction Extracted with ethyl acetate and water, dried over anhydrous sodium sulfate, and distilled off the solvent under reduced pressure to obtain 23.7 g of compound 3 with a yield of 88%. The obtained compound 3 was added in the reaction flask, added 60 ml of methanol and a suitable palladium catalyst, and reacted for 8 hours at 60 ° C. After the reaction was extracted, dried, and the solvent was removed by distillation under reduced pressure, 16.7 g of compound 4 wa...

Embodiment 2

[0026] Add 19.1 g of 2,5-dichlorobenzoic acid (0.1 mol) and 80 ml of methanol into the reaction flask, add a catalytic amount of acid, and reflux at 65~70 °C for 8 hours. After the reaction is over, distill under reduced pressure to remove excess methanol to obtain 19.4 g of methyl 2,5-dichlorobenzoate with a yield of 94.5%. Add the obtained methyl 2,5-dichlorobenzoate (0.095 mol) into the reaction flask, add 19.8 g of bromine (0.12 mol) and 2.5 g of aluminum tribromide, and react at 50 °C for 6 hours. After the reaction Extracted with ethyl acetate and water, dried over anhydrous sodium sulfate, and distilled off the solvent under reduced pressure to obtain 23.9g of compound 3 with a yield of 89%. The obtained compound 3 was added in the reaction flask, added 60 ml of methanol and a suitable palladium catalyst, reacted for 8 hours at 60 ° C, the reaction was extracted, dried, and after the solvent was distilled off under reduced pressure, 16.3 g of compound 4 was obtained. Th...

Embodiment 3

[0028] Add 19.1 g of 2,5-dichlorobenzoic acid (0.1 mol) and 100 ml of methanol into the reaction flask, add a catalytic amount of acid, and reflux at 80 °C for 6 hours. After the reaction, distill off excess methanol under reduced pressure , to obtain 18.9 g of methyl 2,5-dichlorobenzoate with a yield of 92%. Add the obtained methyl 2,5-dichlorobenzoate (0.092 mol) into the reaction flask, add 14.7 g of bromine (0.10 mol) and 2.5 g of aluminum tribromide, and react at 60 °C for 5 hours. After the reaction Extracted with ethyl acetate and water, dried over anhydrous sodium sulfate, and distilled off the solvent under reduced pressure to obtain 20.1 g of compound 3 with a yield of 80%. The obtained compound 3 was added in the reaction flask, added 60 ml of methanol and a suitable palladium catalyst, and reacted for 10 hours at 60 ° C. After the reaction was extracted, dried, and the solvent was distilled off under reduced pressure, 14.5 g of compound 4 was obtained. The yield wa...

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Abstract

The invention relates to a preparation method of dicamba. The method comprises the following steps: preparing 2, 5-dichlorobenzoic acid as a starting raw material; further esterifying with methyl alcohol in an acidic condition; processing to obtain a product; further substituting with bromine under the effect of aluminum tribromide; reacting the obtained product with methyl alcohol under the effect of a catalyst; processing; and further hydrolyzing the obtained product to obtain the final product, namely dicamba. Compared with a traditional synthesizing method, the method has the advantages that few synthesizing steps are performed; the reaction process is simple; the reaction temperature is low; the operation safety is improved; the reaction processing in each step is simple, so that thereaction can be conveniently carried out; and the yield is high.

Description

technical field [0001] The invention relates to the synthesis of organic compounds, in particular to a preparation method of dicamba. Background technique [0002] The chemical name of dicamba is 3,6-dichloro-2-methoxybenzoic acid, which is a benzoic acid herbicide, and is mainly used in the control of annual or perennial broad-leaved weeds in grass crops such as wheat, corn, millet, and rice , with strong selectivity. Dicamba is used for post-emergence spraying. The drug can be quickly absorbed by the leaves, stems, and roots of weeds, conduct upward and downward through the phloem, and mostly concentrate in the meristems and parts with vigorous metabolic activities, hindering the normal activities of plant hormones and thus make it die. Poaceae plants can quickly metabolize and decompose the drug after absorbing it to make it ineffective, so they show strong drug resistance. The market demand for dicamba is huge, but its synthesis route and production technology are mon...

Claims

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Application Information

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IPC IPC(8): C07C51/09C07C65/21
CPCC07C51/09C07C67/08C07C67/307C07C67/31C07C65/21C07C69/76
Inventor 于国权孙霞林马长庆丁华平
Owner JIANGSU CHANGQING AGROCHEMICAL CO LTD
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