Method for preparing terbufos benzthiazuron

Abstract

The invention relates to a preparation method of tebuthiuron, which takes 2-methylamino-5-tert-butyl-1, 3, 4-thiadiazole (I), carbonyl dihalide or the derivatives (II) and methylamine as the raw materials, the tebuthiuron (IV) is prepared and obtained by the following reactions under the alkaline conditions, wherein, X in the carbonyl dihalide or in the derivatives (II) the carbonyl dihalide is a halogen element, and R is the halogen element or the alkoxy with 1 to 4 carbons. The method can effectively solve the potential risks and the serious pollution of the environment caused by using the acutely toxic substance methyl isocyanate in the traditional methods, allow the production of tebuthiuron with high yield, and can effectively make use of the by-products and reclaim the main solvents at the same time.

Description

technical field

[0001] The invention relates to a preparation method of the herbicide terbuthiauron. Background technique

[0002] Tebuthiuron (tebuthiuron), whose structure is shown in formula (IV), is a kind of destructive urea herbicide, which has a good control effect on annual and perennial grasses and broad-leaved weeds, and can be used to control / Except weeds in cultivated land, shrubs in pastures, grasses and broadleaf weeds in sugarcane fields.

[0003]

[0004] In documents such as DE 3113328A1, DE 3314190 and GB 1195672, it has been reported that the preparation method of terbuthiauron, all adopted is made of methyl isocyanate and 2-methylamino-5-tert-butyl-1,3 , 4-thiadiazole reaction mode. Because methyl isocyanate, which is a highly toxic substance, is used in these methods, there is a great potential danger, and the environment is seriously polluted, which is not conducive to large-scale industrial production. Contents of the invention

[0005] In vi...

Examples

Embodiment 1

[0025] Add 2-methylamino-5-tert-butyl-1,3,4-thiadiazole (I) 137g (0.8mol) and 800ml toluene in 2L reactor, slowly warm up to 50°C, turn off the heating system, and In the reaction system, 300 ml of toluene solution of 95 g of triphosgene (0.32 mol in terms of triphosgene) was added dropwise. After the dropwise addition, the temperature was raised to the reflux temperature, and the reaction was stopped after 3 hours of reflux reaction. After removing about 2 / 3 of the volume of toluene in the reaction system under reduced pressure, add 74 g of 40% methylamine aqueous solution (30 g in terms of methylamine, 0.96 mol) dropwise to the residue under ice-water cooling, and add dropwise within 0.5 hours. After completion, add 200 ml of 1 mol / L potassium carbonate (or NaOH) aqueous solution, remove the ice-water bath, wait for the reaction system to warm up naturally and slowly to 30-35°C, and continue the reaction for 4 hours to complete. Filter and wash the filter cake twice with wat...

Embodiment 2

[0027]Add 17.1g (0.1mol) of 2-methylamino-5-tert-butyl-1,3,4-thiadiazole (I) and 100ml toluene into a 200ml reactor, slowly raise the temperature to 50°C, turn off the heating System, dropwise add 40ml of toluene solution of 12g of diphosgene (0.06mol in phosgene) to the reaction system, after the dropwise addition, the temperature is raised to the reflux temperature, and the reaction is continued for 3 hours under reflux to stop the reaction. After 2 / 3 of the volume of toluene in the reactant system was evaporated under reduced pressure, 9.5 g of 40% methylamine aqueous solution (0.12 mol in terms of methylamine) was added dropwise to the residue under ice-water cooling. After the addition was completed within 0.5 hours, , then add 25ml of 30ml of pyridine aqueous solution, remove the ice-water bath, wait for the reaction system to naturally and slowly heat up to 30°C-35°C, and continue the reaction for 4 hours to end. Filter and wash the filter cake twice with water. Separa...

Embodiment 3

[0029] Add 2-methylamino-5-tert-butyl-1,3,4-thiadiazole (I) 35g (0.2mol) and 300ml toluene in a 500ml reactor, and feed into the reaction system within 2 hours at room temperature 25g (0.12mol) of phosgene will be slowly raised to the reflux temperature after passing through, and the reaction will be stopped after continuing the reaction under reflux for 3 hours. After recovering 2 / 3 of the volume of toluene in the reactant system under reduced pressure, add 20 g of 40% methylamine aqueous solution (0.24 mol in terms of methylamine) dropwise to the residue under ice-cooling, the dropwise addition is completed within 0.5 hours, and then add 15ml of triethylamine, remove the ice-water bath, and after the reaction system naturally warms up to room temperature, slowly raise the temperature of the system to 30°C-35°C, and continue the reaction for 4 hours to end. Filter and wash the filter cake twice with water. Separate the toluene in the filtrate and recover the toluene to conce...

technical field

[0001] The invention relates to a preparation method of the herbicide terbuthiauron. Background technique

[0002] Tebuthiuron (tebuthiuron), whose structure is shown in formula (IV), is a kind of destructive urea herbicide, which has a good control effect on annual and perennial grasses and broad-leaved weeds, and can be used to control / Except weeds in cultivated land, shrubs in pastures, grasses and broadleaf weeds in sugarcane fields.

[0003]

[0004] In documents such as DE 3113328A1, DE 3314190 and GB 1195672, it has been reported that the preparation method of terbuthiauron, all adopted is made of methyl isocyanate and 2-methylamino-5-tert-butyl-1,3 , 4-thiadiazole reaction mode. Because methyl isocyanate, which is a highly toxic substance, is used in these methods, there is a great potential danger, and the environment is seriously polluted, which is not conducive to large-scale industrial production. Contents of the invention

[0005] In vi...

Examples

Embodiment 1

[0025] Add 2-methylamino-5-tert-butyl-1,3,4-thiadiazole (I) 137g (0.8mol) and 800ml toluene in 2L reactor, slowly warm up to 50°C, turn off the heating system, and In the reaction system, 300 ml of toluene solution of 95 g of triphosgene (0.32 mol in terms of triphosgene) was added dropwise. After the dropwise addition, the temperature was raised to the reflux temperature, and the reaction was stopped after 3 hours of reflux reaction. After removing about 2 / 3 of the volume of toluene in the reaction system under reduced pressure, add 74 g of 40% methylamine aqueous solution (30 g in terms of methylamine, 0.96 mol) dropwise to the residue under ice-water cooling, and add dropwise within 0.5 hours. After completion, add 200 ml of 1 mol / L potassium carbonate (or NaOH) aqueous solution, remove the ice-water bath, wait for the reaction system to warm up naturally and slowly to 30-35°C, and continue the reaction for 4 hours to complete. Filter and wash the filter cake twice with wat...

Embodiment 2

[0027]Add 17.1g (0.1mol) of 2-methylamino-5-tert-butyl-1,3,4-thiadiazole (I) and 100ml toluene into a 200ml reactor, slowly raise the temperature to 50°C, turn off the heating System, dropwise add 40ml of toluene solution of 12g of diphosgene (0.06mol in phosgene) to the reaction system, after the dropwise addition, the temperature is raised to the reflux temperature, and the reaction is continued for 3 hours under reflux to stop the reaction. After 2 / 3 of the volume of toluene in the reactant system was evaporated under reduced pressure, 9.5 g of 40% methylamine aqueous solution (0.12 mol in terms of methylamine) was added dropwise to the residue under ice-water cooling. After the addition was completed within 0.5 hours, , then add 25ml of 30ml of pyridine aqueous solution, remove the ice-water bath, wait for the reaction system to naturally and slowly heat up to 30°C-35°C, and continue the reaction for 4 hours to end. Filter and wash the filter cake twice with water. Separa...

Embodiment 3

[0029] Add 2-methylamino-5-tert-butyl-1,3,4-thiadiazole (I) 35g (0.2mol) and 300ml toluene in a 500ml reactor, and feed into the reaction system within 2 hours at room temperature 25g (0.12mol) of phosgene will be slowly raised to the reflux temperature after passing through, and the reaction will be stopped after continuing the reaction under reflux for 3 hours. After recovering 2 / 3 of the volume of toluene in the reactant system under reduced pressure, add 20 g of 40% methylamine aqueous solution (0.24 mol in terms of methylamine) dropwise to the residue under ice-cooling, the dropwise addition is completed within 0.5 hours, and then add 15ml of triethylamine, remove the ice-water bath, and after the reaction system naturally warms up to room temperature, slowly raise the temperature of the system to 30°C-35°C, and continue the reaction for 4 hours to end. Filter and wash the filter cake twice with water. Separate the toluene in the filtrate and recover the toluene to conce...

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