Preparation method of pyroxsulam intermediate

A technology for pyresullam and intermediates, applied in the field of preparation of herbicide intermediates, can solve the problems of unsuitability for industrialized production, low purity of target products, harsh reaction conditions, etc., and achieve high condensation reaction yield, low cost, and efficient reaction The effect of high yield

Active Publication Date: 2021-08-24
江苏省农用激素工程技术研究中心有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] The disadvantages of this method are: (1) the cyclization reaction is difficult, most of the products are intermediate states before cyclization, and the purity of the target product is very low, less than 50%; (2) the reaction conditions are relatively harsh, requiring no The water anaerobic environment has high requirements on equipment, and the zinc powder needs to be activated in advance, which is difficult to produce and is not suitable for industrial production
[0009] The disadvantages of this method are: (1) the yield is low, especially the yield of the second step cyclization reaction is only 66%; (2) the product is light brown, the purity is also not high, and it is also not suitable for industrial production

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1）

[0035] The preparation method of the acesulfame intermediate of the present embodiment is specifically as follows:

[0036] ① Add 98.0g methanol, 98.0g (0.5mol) of 4-butoxy-1,1,1-trifluoro-3-buten-2-one, 95.55g (0.525mol, 1.05eq ) into the reaction device, lower the temperature to 5°C, add 99.0g (0.55mol, 1.1eq) of sodium methoxide solution with a concentration of 30wt% dropwise, and control the temperature during the dropping process at 5-10°C. After about 2 hours, the temperature is raised to 15-20°C, stirred and reacted for 8h.

[0037] After the reaction, 300 g of water was added to the reaction system, and the layers were separated to obtain 134.0 g of a red oily liquid with a GC purity (including isomers) of 97.7%.

[0038] ② Add 134.0 g of the red oily liquid obtained in step ① to another reaction device, add 154.0 g of ammonium acetate (2.0 mol, 4 eq) and 2.68 g of hydroquinone while stirring, raise the temperature to 140°C, and keep it warm for 6 hours.

[0039] Aft...

Embodiment 2～ Embodiment 4）

[0044] The difference between each embodiment and embodiment 1 lies in the raw materials of step ①, see Table 1 for details.

[0045] Table 1

[0046] Example 1 Example 2 Example 3 Example 4 4-Alkoxy-1,1,1-trifluoro-3-buten-2-one 4-butoxy-1,1,1-trifluoro-3-buten-2-one 98.0g (0.5mol) 4-butoxy-1,1,1-trifluoro-3-buten-2-one 98.0g (0.5mol) 4-ethoxy-1,1,1-trifluoro-3-buten-2-one 84.0g (0.5mol) 4-ethoxy-1,1,1-trifluoro-3-buten-2-one 84.0g (0.5mol) Trialkyl Phosphoroacetate Trimethyl phosphoacetate 1.05eq Triethyl phosphoroacetate 1.05eq Trimethyl phosphoacetate 1.05eq Triethyl phosphoroacetate 1.05eq intermediate Methyl 3-trifluoromethyl-5-methoxy-5-butoxypentenoate and its isomers 3-Trifluoromethyl-5-methoxy-5-butoxypentenoic acid ethyl ester and its isomers Methyl 3-trifluoromethyl-5-methoxy-5-ethoxypentenoate and its isomers Ethyl 3-trifluoromethyl-5-methoxy-5-ethoxypentenoate and its isomers intermediate weight 134.0g ...

Embodiment 5）

[0048] The preparation method of the acesulfame intermediate of the present embodiment is specifically as follows:

[0049] ①Add 500g methanol, 500g (2.55mol) of 4-butoxy-1,1,1-trifluoro-3-buten-2-one, and 487.5g (2.68mol, 1.05eq) of trimethyl phosphoroacetate To the reaction device, lower the temperature to 5°C, add dropwise 506g (2.81mol, 1.1eq) of sodium methoxide solution with a concentration of 30wt%, and control the temperature during the dropwise addition at 5-10°C. ° C, stirred for 10 h.

[0050] After the reaction, 1500 g of water was added to the reaction system, and the layers were separated to obtain 670 g of a red oily liquid with a GC purity (including isomers) of 97.4%.

[0051]②Add 670g of the red oily liquid obtained in step ① into another reaction device, add 785.7g of ammonium acetate (10.2mol, 4eq) and 13.4g of p-hydroxyanisole under stirring, raise the temperature to 145°C, and keep it warm for 8h.

[0052] After the reaction was finished, 750 g of water...

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Abstract

The invention discloses a preparation method of a pyroxsulam intermediate, which comprises the following steps: (1) carrying out condensation reaction on 4-alkoxy-1,1,1-trifluoro-3-buten-2-one and phosphonoacetic acid trialkyl ester in an alcohol solvent in the presence of sodium alcoholate to generate an intermediate 3-trifluoromethyl-5,5-dialkoxy pentenoic acid alkyl ester and an isomer of the intermediate 3-trifluoromethyl-5,5-dialkoxy pentenoic acid alkyl ester; and (2) carrying out cyclization reaction on the intermediate generated in the step (1) and ammonium acetate in the presence of a polymerization inhibition catalyst to generate 2-hydroxy-4-trifluoromethylpyridine. According to the method disclosed by the invention, hydroquinone and other polymerization inhibition catalysts are added in the cyclization process, so that polymerization side reaction of a condensation intermediate containing double bonds can be avoided, and the reaction yield and the product purity of the cyclization reaction are ensured. Meanwhile, the 4-butoxy-1,1,1-trifluoro-3-buten-2-one and the phosphonoacetic acid trimethyl ester are adopted as the condensation reaction raw materials, so that not only can higher condensation reaction yield be obtained, but also the cost is lower, and the safety is higher.

Description

technical field [0001] The invention belongs to the technical field of preparation of herbicide intermediates, and in particular relates to a preparation method of acesulfame intermediate 2-hydroxy-4-(trifluoromethyl)pyridine. Background technique [0002] Pyrexsulam (also known as methosulam), commonly known as Pyroxsulam in English, is a sulfonamide herbicide developed by Dow AgroSciences, which has a broad herbicidal spectrum, high herbicidal activity, and efficacy Fast acting features. Acesulfame has a very broad herbicidal spectrum, and has a good effect on common grass weeds in wheat fields, and also has a certain control effect on broad-leaved weeds. Its excellent control effect on vicious gramineous weeds such as kangaroo, ryegrass multiflora, wild oats, and hard grass is the outstanding advantage of acesulfame. It has no cross resistance and is widely used in the field of pesticides, and its synthesis is one of the research hotspots in the field of pesticides in r...

Claims

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Application Information

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IPC IPC(8): C07D213/64C07C67/343C07C69/734
CPCC07D213/64C07C67/343C07C69/734
Inventor 蒋旭明杨传鹏刘超邹佩佩孙永辉孔繁蕾
Owner 江苏省农用激素工程技术研究中心有限公司
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