Preparation method of triflusulfonamide sodium salt

Abstract

This invention discloses a method for preparing sodium triflumsulfuron-methyl, which involves a one-step reaction of 3-(2,2,2-trifluoroethoxy)-2-pyridinesulfonamide with 4,6-dimethoxy-2-(phenoxycarbonyl)aminopyrimidine and an aqueous solution of sodium hydroxide in an organic solvent to obtain sodium triflumsulfuron-methyl. The method of this invention not only has a shorter reaction time and is simpler to operate, but also has lower production costs and higher yields, making it suitable for large-scale industrial production.

Description

Technical Field

[0001] This invention belongs to the field of herbicide preparation technology, specifically relating to a method for preparing triflusulfonamide sodium salt. Background Technology

[0002] Triflusulfonyl sodium salt is a sulfonylurea herbicide developed by Syngenta. Its chemical name is N-[(4,6-dimethoxy-2-pyrimidinyl)carbamoyl]-3-(2,2,2-trifluoroethoxy)-pyridine-2-aminosulfonyl sodium salt. After application, triflusulfonyl sodium salt is absorbed by the roots, stems, and leaves of weeds. Affected plants exhibit necrosis of the growing point, chlorosis of leaf veins, and ultimately, death of the entire plant. It is used to control most broadleaf weeds and some grass weeds in cotton and sugarcane fields, and is particularly effective against sedges and nutsedge.

[0003] The existing technologies disclose several methods for preparing triflusulfonamide sodium salt, including the following:

[0004] I. Using 4,6-dimethoxypyrimidine-2-isocyanate (hereinafter referred to as pyrimidine isocyanate) as the starting material, it is first reacted with ammonia in dioxane to obtain 2-aminocarbonylamino-4,6-dimethoxypyrimidine (hereinafter referred to as pyrimidine urea), then reacted with sodium hydride in tetrahydrofuran to obtain pyrimidine urea sodium salt, and finally reacted with 3-(2-trifluoroethoxy)pyridine-2-sulfonyl chloride (hereinafter referred to as pyridine sulfonyl chloride) to obtain trifluorosulfuron sodium salt [see Example H2 of Japanese Patent Document JPH11140081A].

[0005] The specific synthesis route is as follows:

[0006] .

[0007] The drawbacks of this method are that the reaction steps are relatively long, the reaction conditions are relatively harsh, the operation is relatively complex, and the yield is particularly low, with only 59% in the last two steps, making it unsuitable for large-scale industrial production.

[0008] II. Using 4,6-dimethoxypyrimidine-2-isocyanate (hereinafter referred to as pyrimidine isocyanate) as the starting material, it is directly reacted with sodium salt of 3-(2-trifluoroethoxy)pyridine-2-sulfonamide (hereinafter referred to as sodium pyridinesulfonamide) in dioxane or tetrahydrofuran to obtain sodium trifluorosulfonamide [see Example H1 of Japanese Patent Document JPH11140081A].

[0009] The specific synthesis route is as follows:

[0010] .

[0011] The drawback of this method is that the source of the raw material, sodium pyridine sulfonamide, is limited and the price is high, resulting in high production costs and making it unsuitable for large-scale industrial production. Summary of the Invention

[0012] The purpose of this invention is to solve the above-mentioned problems and provide a method for preparing triflusulfonamide sodium salt with shorter reaction steps, simpler operation, lower production cost, and higher yield.

[0013] The technical solution for achieving the objective of this invention is: a method for preparing sodium triflusulfonamide, characterized in that: it is prepared by reacting 3-(2,2,2-trifluoroethoxy)-2-pyridinesulfonamide [hereinafter referred to as pyridinesulfonamide] with 4,6-dimethoxy-2-(phenoxycarbonyl)aminopyrimidine [hereinafter referred to as pyrimidine phenyl ester] and an aqueous solution of sodium hydroxide in an organic solvent in one step to obtain sodium triflusulfonamide.

[0014] The specific synthesis route is as follows:

[0015] .

[0016] The molar ratio of pyridinesulfonamide to pyrimidine phenyl ester is 1:1 to 1:1.2, preferably 1:1.

[0017] The molar ratio of pyridine sulfonamide to sodium hydroxide is 1:1 to 1:2, preferably 1:1 to 1:1.1.

[0018] The reaction temperature is 0–50°C, preferably 5–10°C.

[0019] The reaction time is 2 to 10 hours, preferably 6 hours.

[0020] The organic solvent is one of acetonitrile, dioxane, acetone, N,N-dimethylformamide, and methyl isobutyl ketone, preferably acetonitrile or dioxane.

[0021] The reaction process includes post-processing, which includes filtration, rinsing, and drying.

[0022] The rinsing solvent is the same type of organic solvent used in the reaction; the drying temperature is 100°C.

[0023] The positive effects of this invention are as follows: The method of this invention uses 3-(2,2,2-trifluoroethoxy)-2-pyridinesulfonamide, 4,6-dimethoxy-2-(phenoxycarbonyl)aminopyrimidine, and sodium hydroxide aqueous solution in an organic solvent to react in one step to obtain sodium trifluorosulfonamide. This method not only has a shorter reaction step and simpler operation, but also has lower production cost and higher yield, making it suitable for large-scale industrial production. Detailed Implementation

[0024] (Example 1)

[0025] The specific preparation method of triflusulfonamide sodium salt in this embodiment is as follows:

[0026] Add 84.0 g (0.328 mol) of pyridine sulfonamide, 90.2 g (0.328 mol) of pyrimidine phenyl ester and 520 mL of acetonitrile to a 1000 mL four-necked flask in sequence. After stirring and dissolving, cool to 5 °C and add 28.8 g (0.36 mol) of 50 wt% sodium hydroxide aqueous solution dropwise over about 1 hour. Then keep the reaction at 5–10 °C for 6 hours.

[0027] After the reaction was completed, the sample was filtered, washed with a small amount of acetonitrile, and dried at 100°C to obtain 138.5 g of white crystalline triflusulfonyl sodium salt, with a yield of 92.0% and a purity of 99.2% (HPLC).

[0028] 1 H NMR (400MHz, Chloroform-d) δ: 7.713~7.723(d,1H,J=4,CH), 7.685(s,1H,CH), 7.435~7.456(d,1H, J=8.4,CH), 7.085~7.116(m,1H,CH), 5.583(s,1H,NH), 4.588~4.652(m,2H,CH2), 3.797(s,6H,CH3).

[0029] (Example 2)

[0030] The specific preparation method of triflusulfonamide sodium salt in this embodiment is as follows:

[0031] Add 76.8 g (0.3 mol) of pyridine sulfonamide, 82.5 g (0.3 mol) of pyrimidine phenyl ester and 500 mL of dioxane to a 1000 mL four-necked flask in sequence. After stirring and dissolving, cool to 5 °C and add 24.0 g (0.3 mol) of 50 wt% sodium hydroxide aqueous solution dropwise over about 1 hour. Then keep the reaction at 5–10 °C for 6 hours.

[0032] After the reaction was completed, the sample was filtered, washed with a small amount of dioxane, and dried at 100°C to obtain 125.3 g of white crystalline triflusulfonamide sodium salt, with a yield of 91.0% and a purity of 98.7% (HPLC).

[0033] (Comparative Example 1)

[0034] The specific preparation method of the triflusulfonamide sodium salt in this comparative example is as follows:

[0035] ① Add 76.8g (0.3mol) of pyridine sulfonamide, 82.5g (0.3mol) of pyrimidine phenyl ester, 45.6g (0.3mol) of DBU and 500mL of acetonitrile to a 1000mL four-necked flask in sequence, and react at room temperature for 2h.

[0036] After the reaction was completed, the solvent was evaporated under reduced pressure, and hydrochloric acid and water were added to the residue for acidification, resulting in the precipitation of a white solid. The solid was filtered, washed with a small amount of water, and dried to obtain 124.6 g of triflusulfonamide, with a yield of 95.0% and a purity of 97.5%.

[0037] ② Add 124.6 g (0.285 mol) of triflusulfonamide obtained in step ① and 300 mL of methanol to a 1000 mL four-necked flask, then add 51.3 g of 30 wt% sodium methoxide / methanol solution (containing 0.285 mol of sodium methoxide), and heat to reflux for 30 min.

[0038] After the reaction was completed, most of the solvent was evaporated, and the mixture was cooled to 0-5°C to obtain a viscous solid. The solid was filtered, dried, and 102.0 g of sodium triflusulfonate was obtained, with a yield of 77.9% and a purity of 97.2%.

[0039] The two-step yield was 74.1% based on pyridine sulfonamide.

Claims

1. A process for the preparation of fluthiacet-methyl sodium salt characterized by: It is obtained by one-step reaction of 3-(2,2,2-trifluoroethoxy)-2-pyridinesulfonamide with 4,6-dimethoxy-2-(phenoxycarbonyl)aminopyrimidine and aqueous sodium hydroxide in an organic solvent; the reaction temperature is 0-50℃, the reaction time is 2-10h; the molar ratio of 3-(2,2,2-trifluoroethoxy)-2-pyridinesulfonamide to 4,6-dimethoxy-2-(phenoxycarbonyl)aminopyrimidine is 1:1-1:1.2; the molar ratio of 3-(2,2,2-trifluoroethoxy)-2-pyridinesulfonamide to sodium hydroxide is 1:1-1:

2.

2. The method of preparing flumetsulam sodium salt according to claim 1, characterized by: The organic solvent is one of acetonitrile, dioxane, acetone, N,N-dimethylformamide, methyl isobutyl ketone.

3. The method for preparing flusulfanilamide sodium salt according to claim 2, characterized in that: The organic solvent is acetonitrile or dioxane.

4. The method for preparing flusulfanilamide sodium salt according to claim 1, characterized in that: The reaction is followed by post-treatment; the post-treatment includes suction filtration, rinsing and drying.

5. The method for preparing flusulfanilamide sodium salt according to claim 4, characterized in that: The rinsing solvent is the same as the organic solvent used in the reaction; the drying temperature is 100℃.