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Preparation method of 2-methylamino-5-t-butyl-1,3,4-thiadiazole

A technology of methylamino and methylthiosemicarbazide, which is applied in the direction of organic chemistry, can solve the problems of harsh reaction conditions, environmental pollution, and many by-products, and achieve the goal of less harsh reaction conditions, clean production process, and continuous operation Effect

Active Publication Date: 2016-04-27
JIANGSU HANLIAN BIOTECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

When using phosphorus oxychloride, polyphosphoric acid, phosphorus trichloride, phosphorus pentachloride, this cyclization reaction is difficult to control, and strictly requires anhydrous, and reaction condition is harsher, and by-product is many, and product purity and yield are low. lower
What's more serious is that a large amount of phosphorus-containing wastewater is produced. These phosphorus-containing wastewater are very difficult to deal with, causing serious environmental pollution and not in line with the development direction of green chemistry.
[0006] The literature has not reported the use of solid phosgene as a cyclization reagent to synthesize 2-methylamino-5-tert-butyl-1,3,4-thiadiazole, nor has it reported the use of dimeric phosgene or phosgene as a cyclization agent. Chemical reagents to synthesize 2-methylamino-5-tert-butyl-1,3,4-thiadiazole

Method used

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  • Preparation method of 2-methylamino-5-t-butyl-1,3,4-thiadiazole

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] Add 30g of pivalic acid into a 250mL three-necked flask, add 30mL of toluene to dissolve, raise the temperature to 80°C, and add 43g of solid phosgene in batches. After the addition was complete, the reaction was continued for 2 hours, and the released HCl gas was passed into water. Cool down to room temperature and set aside.

[0028] Add 28g of methylthiosemicarbazide and 30mL of toluene into a 500mL four-neck flask, add 6g of triethylamine, add the above solution dropwise at 100°C under mechanical stirring, and continue the reaction for 3 hours after the dropping is complete. The reaction was stopped, quenched by adding water, the organic layer was separated, and the aqueous layer was extracted with toluene. The organic layers were combined and desolventized to obtain 44.9 g of a white solid with a yield of 98.5% and a purity of 98.6% by HPLC.

Embodiment 2

[0030] Add 30g of pivalic acid into a 250mL three-necked flask, add 30mL of toluene to dissolve, raise the temperature to 80°C, and add 43g of solid phosgene in batches. After the addition was complete, the reaction was continued for 2 hours, and the released HCl gas was passed into water. Cool down to room temperature and set aside.

[0031] Add 28g of methylthiosemicarbazide and 30mL of toluene into a 500mL four-neck flask, add 81g of triethylamine, add the above solution dropwise at 100°C under mechanical stirring, and continue the reaction for 3 hours after the drop is complete. The reaction was stopped, quenched by adding water, the organic layer was separated, and the aqueous layer was extracted with toluene. The organic layers were combined and precipitated to obtain 44.3 g of a white solid with a yield of 97.1% and a purity of 97.6% by HPLC.

Embodiment 3

[0033] Add 30g of pivalic acid into a 250mL three-necked flask, add 30mL of toluene to dissolve, raise the temperature to 80°C, and add 45g of dimeric phosgene in batches. After the addition was complete, the reaction was continued for 2 hours, and the released HCl gas was passed into water. Cool down to room temperature and set aside.

[0034] Add 28g of methylthiosemicarbazide and 30mL of toluene into a 500mL four-neck flask, add 4g of triethylamine, add the above solution dropwise at 100°C under mechanical stirring, and continue the reaction for 3 hours after the drop is complete. The reaction was stopped, quenched by adding water, the organic layer was separated, and the aqueous layer was extracted with toluene. The organic layers were combined and desolventized to obtain 45.1 g of a white solid with a yield of 98.9% and a purity of 98.8% by HPLC.

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Abstract

The invention provides a preparation method of 2-methylamino-5-t-butyl-1,3,4-thiadiazole. Pivalic acid directly used as a raw material reacts with methylthiosemicarbazide with solid phosgene or a phosgene dimer or phosgene as an acylation reagent and a cyclization reagent to synthesize 2-methylamino-5-t-butyl-1,3,4-thiadiazole. The preparation method allows highly pure 2-methylamino-5-t-butyl-1,3,4-thiadiazol to be prepared, has the advantages of very high yield, safe operation, very low production cost, solving of the defects of existing production technologies, environmental protection and no pollution.

Description

technical field [0001] The invention relates to a preparation method of 2-methylamino-5-tert-butyl-1,3,4-thiadiazole. Background technique [0002] 2-methylamino-5-tert-butyl-1,3,4-thiadiazole is the key intermediate of tebuthiuron, and tebuthiuron (tebuthiuron), also known as tebuthiuron, is a systemic broad-spectrum substitution Urea herbicides can be widely used to control weeds in non-cultivated land, shrubs in pastures, gramineous and broad-leaved weeds in sugarcane fields, etc. [0003] The current industrial production method is to take methylthiosemicarbazide and pivaloyl chloride as raw materials, and phosphorus oxychloride as a cyclization reagent, and the equation is as follows: figure 1 shown. [0004] Among them, pivaloyl chloride is prepared by reacting pivalic acid with acylating reagents such as thionyl chloride and phosphorus trichloride. The phosphorus trichloride method generates phosphorous acid, a by-product that is difficult to remove, and generally r...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D285/135
CPCC07D285/135
Inventor 李君
Owner JIANGSU HANLIAN BIOTECH CO LTD
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