阅读说明：本技术 一种双氟磺草胺的制备方法 (Preparation method of florasulam ) 是由 冯维春 邢文国 孟宪兴 陈琦 舒永 魏凤 米鹏 朱军伟 张晓谦 于 2020-12-09 设计创作，主要内容包括：本发明属于有机合成技术领域,具体涉及一种双氟磺草胺的制备方法。本发明以8-氟-5-甲氧基-[1,2,4]三唑[1,5-C]嘧啶-2-磺酰氯、2,6-二氟苯胺为反应原料,3-氨基吡啶为缚酸剂,在溶剂二氯乙烷存在下,发生缩合反应,结束后降温、过滤、干燥后得到双氟磺草胺,反应收率可达98.5％以上,可以大大降低现有工艺价格较高的2,6-二氟苯胺的用量,在具有较高收率的同时,大大降低了生产成本,且能够获得高纯度产物。(The invention belongs to the technical field of organic synthesis, and particularly relates to a preparation method of florasulam. The invention takes 8-fluoro-5-methoxy- [1,2,4] triazolo [1,5-C ] pyrimidine-2-sulfonyl chloride and 2, 6-difluoroaniline as reaction raw materials, 3-aminopyridine as an acid-binding agent, the condensation reaction is carried out in the presence of dichloroethane as a solvent, after the condensation reaction is finished, the temperature is reduced, the filtration and the drying are carried out to obtain the florasulam, the reaction yield can reach more than 98.5 percent, the use amount of the 2, 6-difluoroaniline with higher price in the prior art can be greatly reduced, the production cost is greatly reduced while the yield is higher, and a high-purity product can be obtained.)

1. A preparation method of florasulam is characterized in that 8-fluoro-5-methoxy- [1,2,4] triazolo [1,5-C ] pyrimidine-2-sulfonyl chloride and 2, 6-difluoroaniline are adopted as raw materials, 3-aminopyridine is adopted as an acid-binding agent, and the florasulam is prepared through condensation reaction.

2. The preparation method of florasulam according to claim 1, characterized by comprising the following steps:

(1) adding 8-fluoro-5-methoxy- [1,2,4] triazolo [1,5-C ] pyrimidine-2-sulfonyl chloride, 2, 6-difluoroaniline and 3-aminopyridine into 1, 2-dichloroethane, and heating to 30-60 ℃ to react for 3-8 h to obtain a reaction mixed solution;

(2) and after the reaction is finished, cooling the mixed solution, filtering, rinsing a filter cake, and drying to obtain the florasulam.

3. The method for preparing florasulam as claimed in claim 1, wherein the molar ratio of 8-fluoro-5-methoxy- [1,2,4] triazolo [1,5-C ] pyrimidine-2-sulfonyl chloride to 2, 6-difluoroaniline is 1: 1.1 to 1.25.

4. The preparation method of florasulam as claimed in claim 1, wherein the molar ratio of the 8-fluoro-5-methoxy- [1,2,4] triazolo [1,5-C ] pyrimidine-2-sulfonyl chloride to the 3-aminopyridine is 1: 1.0-1: 2.

5. The method for preparing florasulam as claimed in claim 1, wherein in the step (1), the addition amount of 1, 2-dichloroethane is 4-5 times of the mass of 8-fluoro-5-methoxy- [1,2,4] triazolo [1,5-C ] pyrimidine-2-sulfonyl chloride.

6. The method for preparing florasulam as claimed in claim 1, wherein the condensation reaction temperature in step (1) is 40-50 ℃.

7. The method for preparing florasulam as claimed in claim 1, wherein in step (1), the condensation reaction time is 5 h.

8. The method for preparing florasulam as claimed in claim 1, wherein in step (2), the temperature of the mixed solution is reduced to below 10 ℃ after the reaction.

9. The preparation method of florasulam as claimed in claim 2, characterized in that in the step (2), the filter cake is rinsed by ethanol and dried at 105 +/-5 ℃ to obtain the florasulam product.

Technical Field

The invention belongs to the technical field of organic synthesis, and particularly relates to a preparation method of florasulam.

Background

The florasulam is a triazolopyrimidine sulfonamide herbicide developed by the American Dow agricultural science company, is an ultra-high-efficiency herbicide for treating postemergence stems and leaves of broadleaf weeds in wheat fields, has good persistence and wide weed control spectrum, has stable drug effect at low temperature, is widely applied abroad, is popular with wheat farmers after being put into the market of wheat field herbicides in China, and is valued and concerned by pesticide production enterprises.

Patent WO9937650a1 discloses two methods for preparing florasulam, one is reaction only in the presence of 1, 2-propanediol, yield 88.9%; the other is reaction under the condition of simultaneously existing 1, 2-propylene glycol and naphthalene catalyst, and the yield reaches 98%. Although the yield of the latter method is high, the production cost is greatly increased by using the naphthalene catalyst, and the method uses 2, 6-difluoroaniline in multiple times, so that the redundant 2, 6-difluoroaniline cannot be recycled, thereby causing the production cost to be high. Patent CN103509027A discloses a method for preparing florasulam, which has high yield, but has poor reproducibility, high requirements on material ratio, reaction temperature and reaction time, and is easy to generate impurities.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a method for preparing florasulam, which can greatly reduce the consumption of expensive raw material 2, 6-difluoroaniline, reduce the production cost, ensure the reaction yield to be more than 98.5 percent and obtain a high-purity product.

In order to achieve the purpose, the invention adopts the technical scheme that:

a process for preparing florasulam from 8-fluoro-5-methoxy- [1,2,4] triazolo [1,5-C ] pyrimidine-2-sulfonyl chloride and 2, 6-difluoroaniline through condensation reaction with 3-aminopyridine as acid-binding agent.

The reaction route is as follows:

the method comprises the following specific steps:

(1) adding 8-fluoro-5-methoxy- [1,2,4] triazolo [1,5-C ] pyrimidine-2-sulfonyl chloride, 2, 6-difluoroaniline and 3-aminopyridine into 1, 2-dichloroethane, and heating to 30-60 ℃ to react for 3-8 h to obtain a reaction mixed solution;

(2) and after the reaction is finished, cooling the mixed solution, filtering, rinsing a filter cake, and drying to obtain the florasulam.

The molar ratio of the 8-fluoro-5-methoxy- [1,2,4] triazolo [1,5-C ] pyrimidine-2-sulfonyl chloride to the 2, 6-difluoroaniline is 1: 1.1 to 1.25.

The molar ratio of the 8-fluoro-5-methoxy- [1,2,4] triazolo [1,5-C ] pyrimidine-2-sulfonyl chloride to the 3-aminopyridine is 1: 1.0-1: 2.

In the step (1), the adding amount of the 1, 2-dichloroethane is 4-5 times of the mass of the 8-fluoro-5-methoxy- [1,2,4] triazolo [1,5-C ] pyrimidine-2-sulfonyl chloride.

In the step (1), the condensation reaction temperature is 40-50 ℃.

In the step (1), the condensation reaction time is 5 h.

In the step (2), after the reaction is finished, the temperature of the mixed solution is reduced to below 10 ℃.

In the step (2), the filter cake is rinsed by ethanol and dried at 105 +/-5 ℃ to obtain the florasulam product.

Compared with the prior art, the invention has the beneficial effects that:

aiming at the current situations that the existing process uses 2, 6-difluoroaniline and naphthalene catalysts which are multiple in amount, cannot be recycled, and therefore is high in production cost and poor in process reproducibility, the invention designs a novel florasulam process, the novel process can greatly reduce the usage amount of expensive raw materials 2, 6-difluoroaniline, the production cost is reduced, the reaction yield can reach more than 98.5%, and high-purity products can be obtained.

Detailed Description

In order to better understand the technical scheme of the present invention, the following detailed description of the present invention is provided by way of examples, but the present invention should not be construed as limited to the above description.

Example 1

200ml of dichloroethane solvent, 53.3g, 0.2mol of 8-fluoro-5-methoxy- [1,2,4] triazolo [1,5-C ] pyrimidine-2-sulfonyl chloride, 32.3g of 0.25mol of 2, 6-difluoroaniline and 18.8g of acid-binding agent 3-aminopyridine are added into a reaction bottle, the temperature is raised to 40 ℃, the reaction is controlled for 5 hours, after the reaction is finished, the temperature is reduced to be below 10 ℃, the filtration is carried out, 70.8g of florasulam is obtained after a filter cake is rinsed by ethanol and dried, and the yield is 98.5%.

Example 2

200ml of dichloroethane solvent, 53.3g, 0.2mol of 8-fluoro-5-methoxy- [1,2,4] triazolo [1,5-C ] pyrimidine-2-sulfonyl chloride, 28.4g of 0.22mol2, 6-difluoroaniline and 18.8g of acid-binding agent 3-aminopyridine are added into a reaction bottle, the temperature is raised to 40 ℃, the reaction is controlled for 5 hours, after the reaction is finished, the temperature is reduced to be below 10 ℃, the filtration is carried out, 71.3g of florasulam is obtained after a filter cake is rinsed by ethanol and dried, and the yield is 99.2%.

Example 3

200ml of dichloroethane solvent, 53.3g, 0.2mol of 8-fluoro-5-methoxy- [1,2,4] triazolo [1,5-C ] pyrimidine-2-sulfonyl chloride, 32.3g of 0.25mol of 2, 6-difluoroaniline and 18.8g of acid-binding agent 3-aminopyridine are added into a reaction bottle, the temperature is raised to 50 ℃, the reaction is controlled for 5 hours, after the reaction is finished, the temperature is reduced to be below 10 ℃, the filtration is carried out, 70.8g of florasulam is obtained after a filter cake is rinsed by ethanol and dried, and the yield is 98.6%.

Example 4

200ml of dichloroethane solvent, 53.3g, 0.2mol of 8-fluoro-5-methoxy- [1,2,4] triazolo [1,5-C ] pyrimidine-2-sulfonyl chloride, 32.3g of 0.25mol of 2, 6-difluoroaniline and 22.6g of acid-binding agent 3-aminopyridine are added into a reaction bottle, the temperature is raised to 50 ℃, the reaction is controlled for 5 hours, after the reaction is finished, the temperature is reduced to be below 10 ℃, the filtration is carried out, 71.1g of florasulam is obtained after a filter cake is rinsed by ethanol and dried, and the yield is 99.0%.

Example 5

175ml of dichloroethane solvent, 53.3g, 0.2mol of 8-fluoro-5-methoxy- [1,2,4] triazolo [1,5-C ] pyrimidine-2-sulfonyl chloride, 32.3g of 0.25mol of 2, 6-difluoroaniline and 28.2g of acid-binding agent 3-aminopyridine are added into a reaction bottle, the temperature is raised to 30 ℃, the reaction is controlled for 8 hours, after the reaction is finished, the temperature is reduced to be below 10 ℃, the filtration is carried out, 70.6g of florasulam is obtained after a filter cake is rinsed by ethanol and dried, and the yield is 98.3%.

Example 6

215ml of dichloroethane solvent, 53.3g, 0.2mol of 8-fluoro-5-methoxy- [1,2,4] triazolo [1,5-C ] pyrimidine-2-sulfonyl chloride, 32.3g of 0.25mol of 2, 6-difluoroaniline and 32g of acid-binding agent 3-aminopyridine are added into a reaction bottle, the temperature is raised to 60 ℃, the reaction is controlled for 3 hours, after the reaction is finished, the temperature is reduced to be below 10 ℃, the filtration is carried out, 71.2g of florasulam is obtained after a filter cake is rinsed by ethanol and dried, and the yield is 99.1%.