Preparation method of flufenacet

A technology of flufenacet and flufenacet, which is applied in the field of preparation of flufenacet, can solve the problems of not obtaining yield, increasing the possibility of competitive side reactions, and reducing yield, and achieves that the process conditions are not harsh , the synthesis method is simple, the effect of less environmental pollution

Inactive Publication Date: 2016-06-08
ZHEJIANG YONGTAI TECH CO LTD
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  • Description
  • Claims
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Problems solved by technology

[0005] The disadvantage of this route is the formation of large amounts of sulfur-containing waste products during the synthesis of the intermediate 2-thiamphenyl-5-trifluoromethyl-1,3,4-thiadiazole
In addition, another problem with this approach, as shown in Scheme II, is the number of synthetic steps required to prepare 2-thiamphenicol-5-trifluoromethyl-1,3,4-thiadiazole, in which each Synthetic steps all result in reduced yields and increased potential for competing side reactions, thus requiring effort in purifying intermediates and final products and may not yield optimal yields

Method used

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  • Preparation method of flufenacet

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Embodiment 1

[0034] The preparation of embodiment 12-amino-5-trifluoromethyl-1,3,4-thiadiazole

[0035] Thiosemicarbazide (145g, 1.59mol) was suspended in 1L of 1,4-dioxane, stirred mechanically; adding CF 3 COOH (120 mL, 1.59 mol); POCl was added dropwise 3 (150mL, 1.59mol), the temperature rises obviously, after adding in about 30 minutes, the reaction solution first becomes extremely thick and then slightly thinner; the external temperature is 110°C for 3 hours under reflux reaction, a large amount of HCl gas is generated, the reaction solution gradually becomes thinner, and a jelly-like solid settling;

[0036] The reaction solution was allowed to stand for 30 minutes, the supernatant was poured out, 1 L of ice water was added to the residue, and mechanically stirred; the pH was adjusted to 9 with 50% NaOH solution (~2eq, 3.2mol), and a solid was precipitated, and the mother liquor was cooled to 20°C. The solid was obtained by suction filtration, washed once with ice water, and dried...

Embodiment 22

[0037] The preparation of embodiment 22-chloro-5-trifluoromethyl-1,3,4-thiadiazole

[0038] 2-amino-5-trifluoromethyl-1,3,4-thiadiazole (130g, 0.768mol) was suspended in 1.5L of 37wt% hydrochloric acid, mechanically stirred; Cu powder (18.2g, 0.284mol) was added; cold To internal temperature -10°C; add dropwise 350mL containing NaNO 2 (212g, 3.07mol, 4eq) aqueous solution, the temperature is controlled at -10°C to -5°C, and it takes about 2h to complete the addition.

[0039]During the reaction process, brown gas is always generated, and the reaction solution becomes very thick, and a large amount of solids are generated (it is easy to spray if the drop is too fast); then stir at -5°C to 5°C for 1 to 2 hours, and the reaction solution becomes thinner; the temperature rises to 40 ℃~50℃ and then stirred for 2~3 hours, the reaction solution gradually became thinner, and turned into a brown-yellow suspension;

[0040] After cooling to room temperature, CH was added to the reacti...

Embodiment 3

[0043] The preparation of embodiment 3 flufenacet

[0044] Potassium tert-butoxide (tBuOK) (2.7g, 0.0236mol) was suspended in 50mL tert-butanol (tBuOH), in a water bath at room temperature (around 25°C); add 2-hydroxy-N-(4-fluoroaniline)-N-( 1-methylethyl) acetamide (5g, 0.0236mol); Add 2-chloro-5-trifluoromethyl-1,3,4-thiadiazole (4.5g, 0.0236mol) dropwise under stirring, react The system will be slightly exothermic and form a light yellow suspension; then stir at room temperature for 1-2 hours until the reaction is complete. The reaction formula is as follows:

[0045]

[0046] Add CH to the reaction solution 2 Cl 2 300mL, washed twice with brine with a concentration of 20%~saturated (with emulsification), took the organic phase to dry, and recovered CH 2 Cl 2 The crude product of flufenacet (8.2 g, 96%) was obtained. TLC basically has no impurities, and the purity is 89% as detected by HPLC.

[0047] The crude product of flufenacet can be refined by continuous rec...

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Abstract

The invention discloses a preparation method of flufenacet, and belongs to the technical field of pesticide preparation. The method comprises the steps: adding 2-hydroxy-N-(4-fluoroaniline)-N-(1-methylethyl)acetamide into an alkali-containing organic solvent A, dropping 2-chloro-5-trifluoromethyl-1,3,4-thiadiazole into the reaction liquid, carrying out a reaction at room temperature, adding an organic solvent B, extracting, washing with water, drying, and concentrating to obtain a crude product flufenacet; and refining the crude product to obtain the pure product flufenacet. The preparation method has the advantages that the required raw materials are easy to obtain, less pollution to the environment exists, the synthesis is simple and convenient, the process conditions are not harsh, the yield can reach more than or equal to 85%, the purity can reach more than or equal to 98%, and the preparation method is suitable for industrialized production.

Description

technical field [0001] The invention belongs to the technical field of pesticide preparation, and in particular relates to a preparation method of flufenacet. Background technique [0002] Fluthiamide, N-(4-fluorophenyl)-N-(1-methylethyl)-2[(5-trifluoromethyl-1,3,4-thiadiazole- 2-yl)oxy]acetamide, N-(4-fluorophenyl)-N-(1-methylethyl)-2-[(5-trifluoromethyl-1,3,4-thiadiazol-2-yl)oxy]acetamide, is A new high-efficiency, low-toxicity and broad-spectrum pesticide. It is an aryloxyamide herbicide developed by Bayer AG of Germany. It plays a role mainly by inhibiting cell division and growth, and can effectively control many annual grass weeds such as multi-flowered ryegrass, etc., as well as the pre-emergence and early post-emergence stages of some broad-leaved weeds. It can be used for corn before planting or pre-emergence 1. Weeding in soybean fields, weeding before planting of potatoes or before seedlings of potatoes and sunflowers, and post-emergence of wheat, barley, rice,...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D285/13
Inventor 孙智华戴伊如
Owner ZHEJIANG YONGTAI TECH CO LTD
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