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Method for preparing 2-amino-5-aryloxy methylene-1,3,4-thiadiazole

A technology of aryloxymethylene and thiadiazole, applied in the field of 2-amino-5-aryloxymethylene-1, which can solve the problems of environmental pollution, high toxicity, and difficulty in purchasing, and achieve short reaction time , low toxicity and high yield

Inactive Publication Date: 2012-07-25
SHAANXI UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although this method successfully synthesized a 2,5-disubstituted thiadiazole, however, due to POCl 3 It is highly toxic, pollutes the environment, and is a chemical control product, so it is not easy to buy, so POCl is used 3 The preparation of 2,5-disubstituted thiadiazoles as a condensation agent is not a simple and economical industrial method

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] In the first step, add 0.0060mol naphthyloxyacetic acid and 0.0040mol thiosemicarbazide to a dry three-necked flask, then add 5.0ml 1,4-dioxane, and add 1.0ml vitriol dropwise under stirring (add vitriol dropwise). There will be exothermic phenomenon when it reaches the flask, so the flow rate should be controlled, and the dripping should be done slowly to prevent carbonization, and the temperature of the mixed solution should be kept at about 25°C during the whole dropping process), and the stirring and reflux reaction should be carried out after the dropping. Hour;

[0024] In the second step, after the stirring is finished, the resulting mixed solution is cooled to room temperature, and poured into a beaker containing 10g of ice (the function of ice here is mainly to reduce the temperature, so that the crude product is separated out as much as possible), and the mass fraction is used under stirring. Adjust PH to 8-9 with 50% sodium hydroxide, filter the precipitated...

Embodiment 2

[0026] In the first step, add 0.0060mol of naphthyloxyacetic acid and 0.0045mol of thiosemicarbazide to a dry three-necked flask, then add 5.0ml of 1,4-dioxane, add 1.0ml of concentrated sulfuric acid dropwise under stirring, and stir and reflux for 4.5 Hour;

[0027] In the second step, after the stirring is completed, cool the resulting mixture to room temperature, pour it into a beaker containing 10 g of ice, and adjust the pH to 8 to 9 with 50% sodium hydroxide under stirring, and filter the precipitated solid After washing with a small amount of water, the crude product was obtained, and the crude product was recrystallized with absolute ethanol to obtain a white powdery solid, which was 2-amino-5-naphthyloxymethylene-1,3,4-thiadiazole, and the yield was 85 %, mp is 213-214°C.

Embodiment 3

[0029] In the first step, add 0.0060mol of naphthyloxyacetic acid and 0.0050mol of thiosemicarbazide to a dry three-necked flask, then add 5.0ml of 1,4-dioxane, add 1.0ml of concentrated sulfuric acid dropwise under stirring, and stir under reflux to react 5 Hour;

[0030] In the second step, after the stirring is completed, cool the resulting mixture to room temperature, pour it into a beaker containing 10 g of ice, and adjust the pH to 8 to 9 with 50% sodium hydroxide under stirring, and filter the precipitated solid After washing with a small amount of water, the crude product was obtained, and the crude product was recrystallized with absolute ethanol to obtain a white powdery solid, which was 2-amino-5-naphthyloxymethylene-1,3,4-thiadiazole, and the yield was 87 %, mp is 213-214°C.

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PUM

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Abstract

The invention relates to a method for preparing 2-amino-5-aryloxy methylene-1,3,4-thiadiazole. The method comprises the following steps: step 1, adding A mol of aryloxyacetic acid and B mol of thiosemicarbazide into a dry three-mouth flask; adding C ml of 1,4-dioxane; dropwise adding D ml of concentrated sulfuric acid while stirring; and performing reflux for 4-6h while fully stirring to obtain a mixed solution; and step 2, cooling the mixed solution obtained in the step 1 to be room temperature; pouring into a beaker containing with ice; regulating the pH value by a sodium hydroxide solution to be 8-9; filtering and washing the separated solid to obtain a crude product; and re-crystallizing the crude product by using absolute ethanol to obtain 2-amino-5-aryloxy methylene-1,3,4-thiadiazole, wherein A:B = 6:(4-6); and C = 5D = 5000A / 6. According to the method for preparing 2-amino-5-aryloxy methylene-1,3,4-thiadiazole, concentrated sulfuric acid is adopted as a condensating agent, raw materials are cheap and easily accessible, and the yield is high.

Description

【Technical field】 [0001] The invention belongs to the field of chemical synthesis, in particular to a method for 2-amino-5-aryloxymethylene-1,3,4-thiadiazole. 【Background technique】 [0002] 1,3,4-Thiadiazole is a class of five-membered heterocyclic compounds containing sulfur and nitrogen heteroatoms, mainly in the form of derivatives after the hydrogens at the 2 and 5 positions are substituted. 2,5-disubstituted-1,3,4-thiadiazole compounds have biological activity, are important pharmaceutical and chemical intermediates, and can be used in anti-inflammatory, anti-convulsant, anti-tumor and other medical fields. In addition, it is also widely used in the field of pesticides, with herbicide, insecticide, antibacterial and other effects. Therefore, the synthesis of such compounds is of great significance in real life. In view of this, in recent years, the synthesis of 2,5-disubstituted-1,3,4-thiadiazole derivatives has attracted widespread attention of chemists at home and ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D285/135
Inventor 刘玉婷王捷尹大伟元方苏宝君
Owner SHAANXI UNIV OF SCI & TECH