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Method for preparing 5-cyclopropyl-4-[2-methylthio-4-(trifluoromethyl)benzoyl] isoxazole

A trifluoromethyl phenyl and trifluoromethyl technology, applied in the field of pesticide chemistry, can solve problems such as reducing product purity and affecting quality, and achieve the effects of reducing production costs, low production costs, and reducing the number of recrystallizations

Active Publication Date: 2015-04-22
JIANGSU FLAG CHEM IND
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Generate the following impurity 1 4-cyclopropaneformyl-5-[2-methylthio-4-(trifluoromethyl)phenyl]isoxazole, which reduces the product purity and affects the quality

Method used

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  • Method for preparing 5-cyclopropyl-4-[2-methylthio-4-(trifluoromethyl)benzoyl] isoxazole
  • Method for preparing 5-cyclopropyl-4-[2-methylthio-4-(trifluoromethyl)benzoyl] isoxazole
  • Method for preparing 5-cyclopropyl-4-[2-methylthio-4-(trifluoromethyl)benzoyl] isoxazole

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] Example 1: Preparation of 1-(4-trifluoromethyl-2-methylthio-phenyl)-3-cyclopropyl-2-ethoxymethylenepropane-1,3-dione (II);

[0032]Add 183.8 grams (1.24mol) of triethyl orthoformate and raw material 3-cyclopropyl-1-(2-methylthio-4-trifluoromethylphenyl) in a 1000ml four-necked flask equipped with a rectifying column Propyl-1,3-diketone 250g (0.83mol) is heated and stirred to 115-125°C, and 168.9g (1.66mol) of acetic anhydride is added dropwise under the control of this temperature, and the low boiling point generated by the reaction is fractionated while adding. ( ≤ 100°C ) The by-products are dropped in about 1 hour, and kept at this temperature for 2 hours after the drop is completed, and the GC detects that there is no raw material to stop the reaction. The reaction solution was cooled to 70-80°C and distilled under negative pressure until the internal temperature reached a maximum of 120°C (0.09Mp water pump) and kept for 30 minutes until no liquid flowed out, and ...

Embodiment 2

[0034] Example 2: Preparation of 5-cyclopropyl-4-[2-methylthio-4-(trifluoromethyl)benzoyl]isoxazole;

[0035] 15.98g (0.23mol) of hydroxylamine hydrochloride was dissolved in 42g of water at 10-20°C and stirred to dissolve, and 17.37g (0.207mol) of sodium bicarbonate was added in batches at 10-25°C under stirring to adjust the pH of the solution to 3.5-5. Prepare 72.62g (0.2mol) of 1-(4-trifluoromethyl-2-methylthio-phenyl)-3-cyclopropyl-2-ethoxymethylenepropane-1,3-dione and mix 109 g of dichloromethane was made into a solution, which was added dropwise to the above-prepared aqueous solution of hydroxylamine at 10-15°C. After the drop was completed, it was incubated and stirred at 10-25°C for 5 hours. GC detected 1-(4-trifluoromethyl- 2-methylthio-phenyl)-3-cyclopropyl-2-ethoxymethylenepropane-1,3-dione until the reaction is complete. After the reaction was completed, the reaction solution was allowed to stand for stratification, and the lower organic phase solution was sep...

Embodiment 3

[0037] Example 3: Preparation of 5-cyclopropyl-4-[2-methylthio-4-(trifluoromethyl)benzoyl]isoxazole;

[0038] 15.98g (0.23mol) of hydroxylamine hydrochloride was dissolved in 42g of water at 10-25°C and stirred to dissolve, and 8.28g (0.207mol) of sodium hydroxide was added in batches at 10-25°C under stirring to adjust the pH of the solution to 3.5-5. . Prepare 72.62g (0.2mol) of 1-(4-trifluoromethyl-2-methylthio-phenyl)-3-cyclopropyl-2-ethoxymethylenepropane-1,3-dione and mix 109 grams of dichloromethane was made into a solution, which was added dropwise to the above-prepared aqueous solution of hydroxylamine at 10-15°C, and stirred and reacted at 10-25°C for 3 hours. GC detected 1-(4-trifluoromethyl-2- Methylthio-phenyl)-3-cyclopropyl-2-ethoxymethylenepropane-1,3-dione until the reaction is complete. After the reaction was completed, the reaction solution was divided into two layers, and the lower organic phase solution was separated; the upper aqueous phase solution wa...

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Abstract

The invention relates to a method for preparing a herbicide isoxaflutole intermediate, namely, 5-cyclopropyl-4-[2-methylthio-4-(trifluoromethyl)benzoyl] isoxazole. The method comprises the following steps: condensing 3-cyclopropyl-1-(2-methylthio-4-trifluoromethylphenyl)propyl-1,3-dione and triethyl orthoformate as starting materials to prepare 1-(4-trifluoromethyl-2-methylthio-phenyl)-3-cyclopropyl-2-ethoxymethylenepropane-1,3-dione (a compound II) and enabling the compound II to react with an aqueous solution of hydroxylamine hydrochloride and inorganic base in an organic solvent to prepare 5-cyclopropyl-4-[2-methylthio-4-(trifluoromethyl)benzoyl] isoxazole (a compound I). The total yield of two steps is greater than 90.0%, the content of 5-cyclopropyl-4-[2-methylthio-4-(trifluoromethyl)benzoyl] isoxazole is higher than the 98.0% and the content of impurity is less than 0.80%; and the preparation process has the advantages of simplicity in process, low cost, mild reaction conditions and less three wastes and is suitable for industrial production.

Description

technical field [0001] The invention relates to the field of pesticide chemistry, in particular to a key intermediate of the herbicide isoxaflutole, 5-cyclopropyl-4-[2-methylthio-4-(trifluoromethyl)benzoyl]iso Process for the preparation of oxazole (compound I). Background technique [0002] Isoxaflutole (isoxaflutole) is an isoxazole herbicide discovered by Rhone-Planck (now Bayer) in 1992. It has good systemic activity and can be absorbed through the roots and leaves of plants. Afterwards, it is transmitted to the whole plant and can be rapidly converted into biologically active DKN in the plant. Launched in Jamaica in 1996, it is used to control broadleaf weeds and grass weeds in corn and sugarcane fields; it has been registered in more than 30 countries. [0003] Among them, 5-cyclopropyl-4-[2-methylthio-4-(trifluoromethyl)benzoyl]isoxazole (compound I) is a key intermediate for the synthesis of the herbicide isoxaflutole. It undergoes a one-step oxidation reaction to...

Claims

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Application Information

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IPC IPC(8): C07D261/08
CPCC07D261/08
Inventor 王凤云王正旭冯美丽侯远昌吴耀军
Owner JIANGSU FLAG CHEM IND
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