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Synthesis method of key intermediate of tebuthiuron, namely 2-methylamino-5-tert-butyl-1, 3, 4-thiadiazole

A technology of terbutazone and methylamino, which is applied in the field of compound preparation, can solve the problems of not conforming to the development direction of green chemistry, difficult wastewater treatment, serious environmental pollution, etc., and achieves high atom economy and high yield , the effect of less by-products

Inactive Publication Date: 2013-09-11
ZHEJIANG HETIAN CHEM CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Because phosphorus-containing dehydration reagents are used in these literature reports and the dosage is several times that of the reaction substrate, this type of process will produce a large amount of phosphorus-containing wastewater, which is difficult to treat and seriously pollutes the environment, which is not in line with the development of green chemistry. direction

Method used

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  • Synthesis method of key intermediate of tebuthiuron, namely 2-methylamino-5-tert-butyl-1, 3, 4-thiadiazole
  • Synthesis method of key intermediate of tebuthiuron, namely 2-methylamino-5-tert-butyl-1, 3, 4-thiadiazole

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Embodiment 1

[0023] Add 10.5 g (0.1 mol) of 99% 4-methyl-3-thiosemicarbazide (I) and 30 mL of 1,2-dichloroethane to a 100 mL reaction flask, heat it to 80°C, turn off the heating system, 18.3g (0.15mol) of trimethylacetyl chloride was added dropwise to the system, the reaction was exothermic after the dropwise addition, the internal temperature could rise to 83°C, and the dichloroethane was refluxed. After the dropwise addition, the heating system was turned on to continue to keep warm and reflux. Cool down when no hydrogen chloride gas is released. When the internal temperature drops to 15-20 °C, add 13.3 g (0.1 g) of chlorosulfonic acid dropwise. During the dropwise addition, use ice water to control the internal temperature to not exceed 25 °C. The reaction was incubated at -20°C for 1 hour. Add 20% aqueous sodium hydroxide solution and adjust the pH to about 8. At this time, the internal temperature can reach 50-60°C due to acid-base neutralization and exotherm, separate the organic la...

Embodiment 2

[0025] Add 10.5 g (0.1 mol) of 99% 4-methyl-3-thiosemicarbazide (I) and 30 mL of 1,2-dichloroethane to a 100 mL reaction flask, heat it to 80°C, turn off the heating system, 18.3g (0.15mol) of trimethylacetyl chloride was added dropwise to the system, the reaction was exothermic after the dropwise addition, the internal temperature could rise to 83°C, and the dichloroethane was refluxed. After the dropwise addition, the heating system was turned on to continue to keep warm and reflux. When no hydrogen chloride gas is released, 10.2 g (0.1 g) of acetic anhydride was added dropwise under reflux. After the dropwise addition was completed, the reaction was kept under reflux for 1 hour, and the dichloroethane and by-produced acetic acid were recovered under reduced pressure, and 20 mL of dichloroethane was added. Using 20% ​​aqueous sodium hydroxide solution, adjust the pH to about 8, keep the internal temperature at 50-60 ° C, separate the organic layer, and recover dichloroethane ...

Embodiment 3

[0027] Add 10.5 g (0.1 mol) of 99% 4-methyl-3-thiosemicarbazide (I) and 30 mL of 1,2-dichloroethane to a 100 mL reaction flask, heat it to 80°C, turn off the heating system, 18.3g (0.15mol) of trimethylacetyl chloride was added dropwise to the system, the reaction was exothermic after the dropwise addition, the internal temperature could rise to 83°C, and the dichloroethane was refluxed. After the dropwise addition, the heating system was turned on to continue to keep warm and reflux. When no hydrogen chloride gas was released, 7.9 g (0.1 g) of acetyl chloride was added dropwise under reflux. After the dropwise addition was completed, the reaction was kept under reflux for 1 hour, and the dichloroethane and by-product acetic acid were recovered under reduced pressure, and then 20 mL of dichloroethane was added. Using 20% ​​aqueous sodium hydroxide solution, adjust the pH to about 18, keep the internal temperature at 50-60 ° C, separate the organic layer, and recycle dichloroeth...

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Abstract

The invention discloses a synthesis method of a key intermediate of tebuthiuron, namely 2-methylamino-5-tert-butyl-1, 3, 4-thiadiazole. Derivatives of 4-methyl-3-thiosemicarbazide and trimethylacetic acid are taken as raw materials, and condensation and dehydration cyclization reactions are performed under acid conditions in the presence of an organic solvent medium and a hydration agent to obtain the 2-methylamino-5-tert-butyl-1, 3, 4-thiadiazole. According to the synthesis method disclosed by the invention, environmental pollution caused by a large amount of wastewater containing phosphorus, which is produced by taking phosphoric acid, polyphosphoric acid and the like as dehydration reagents, can be effectively avoided; simultaneously, the reaction yield is high, byproducts are few, and the solvent can be recovered and applied mechanically; and the synthesis method further has the advantage of very high atom economy and is in line with the direction of green chemical development.

Description

technical field [0001] The invention belongs to the field of compound preparation, in particular to a method for synthesizing a green and pollution-free key intermediate 2-methylamino-5-tert-butyl-1,3,4-thiadiazole of thiazolone. Background technique [0002] Tebuthiuron is a biocidal urea herbicide, which has good control effect on annual and perennial grasses and broadleaf weeds, and can be used for the control of non-arable weeds and pastures. Shrubs, grasses and broadleaf weeds in sugarcane fields. [0003] [0004] The structural formula of terbufenuron is shown in V. In DE3113328A1, DE3314190 and GB1195672, methyl isocyanate and 2-methylamino-5-tert-butyl-1,3,4-thiadiazole are used to react The method of synthesizing terbutazone; in documents such as US3803164A, US3887572A, US4283543A, etc., the key intermediate 2-methylamino-5-tert-butyl-1,3,4-thiadiazole synthesis method has been reported, all using Under the action of phosphorus-containing dehydration reagents ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D285/135
Inventor 朱颜吴敏华杨建萍吴引儿
Owner ZHEJIANG HETIAN CHEM CO LTD
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