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A kind of preparation method of 1,2-dihydro-3,6-pyridazinedione

A technology of pyridazine diketone and dihydro, which is applied in the field of preparation of 1,2-dihydro-3,6-pyridazine diketone, can solve the problems of unfavorable environmental protection, affecting human health, increasing synthesis production cost, etc. Achieve the effect of reducing the pressure of environmental pollution, reducing waste water and reducing production costs

Active Publication Date: 2021-08-13
SHANGHAI SHISI CHEM PROD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] (1) After the reaction, a large amount of waste water containing inorganic salts and organic acid salts will be produced, which is not conducive to environmental protection
[0010] (2) The use of organic solvents and the use of organic acid catalysts (especially rare earth compound catalysts) increase the cost of synthetic production
[0011] (3) The synthesized products all contain residual toxic hydrazine hydrate components, which indirectly affect people's health

Method used

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  • A kind of preparation method of 1,2-dihydro-3,6-pyridazinedione
  • A kind of preparation method of 1,2-dihydro-3,6-pyridazinedione

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Experimental program
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Effect test

Embodiment 1

[0037] In 250 milliliters of three-necked flasks with stirring and reflux devices, drop into 50 grams of 98% maleic anhydride (0.5mol) and 50 grams of water earlier, start stirring, and slowly add 64.8 grams of 50% aqueous urea ( 0.54mol), then control the temperature of the material at 10-40°C, add dropwise 63.7 grams of 27.5% hydrogen peroxide (0.515mol), heat to reflux, emit carbon dioxide, and keep warm at 106°C for 5 hours. After the reaction is over, the material is released and allowed to cool and crystallize. Use a centrifuge to separate the crystals from the mother liquor, wash the crystals with a small amount of water, centrifuge until the material is dry, and then place the material in a desiccator for drying. After drying, when the material was cooled to normal temperature, 51.6 grams of 1,2-dihydro-3,6-pyridazinedione product was obtained, the product content (HPLC) was 98.5%, and the yield (calculated as maleic anhydride) was 90.76 %.

Embodiment 2

[0039] In 250 milliliters of there-necked flasks with stirring and reflux devices, drop into 50 grams of 98% maleic anhydride (0.5mol) and 100 grams of water earlier, start stirring, and slowly add 64.8 grams of 50% aqueous urea ( 0.54mol), then the material temperature was controlled at 10-40°C, 37.4 grams of 50% hydrogen peroxide (0.55mol) was added dropwise, heated to reflux, and carbon dioxide was released, and kept at 110°C for 3 hours. After the reaction is over, the material is released and allowed to cool and crystallize. Use a centrifuge to separate the crystals from the mother liquor, wash the crystals with a small amount of water, centrifuge until the material is dry, and then place the material in a desiccator for drying. After drying, when the material was cooled to normal temperature, 49.8 grams of 1,2-dihydro-3,6-pyridazinedione product was obtained, the product content (HPLC) was 98.9%, and the yield (calculated as maleic anhydride) was 87.95 %.

Embodiment 3

[0041] In 250 milliliters of there-necked flasks with stirring and reflux devices, drop into 50 grams of 98% maleic anhydride (0.5mol) and 50 grams of water earlier, start stirring, and slowly add 72 grams of 50% aqueous urea ( 0.6mol), then control the temperature of the material at 10-40°C, add 71 grams of 27.5% hydrogen peroxide (0.574mol) dropwise, heat to reflux, emit carbon dioxide, and keep warm at 95°C for 8 hours. After the reaction is over, the material is released and allowed to cool and crystallize. Use a centrifuge to separate the crystals from the mother liquor, wash the crystals with a small amount of water, centrifuge until the material is dry, and then place the material in a desiccator for drying. After drying, when the material was cooled to normal temperature, 50 grams of 1,2-dihydro-3,6-pyridazinedione product was obtained, the product content (HPLC) was 98.1%, and the yield (calculated as maleic anhydride) was 87.59 %.

[0042] The content of the produc...

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Abstract

A method for preparing 1,2-dihydro-3,6-pyridazine dione disclosed in the invention comprises the following steps: in a reactor with a stirring and reflux device, firstly put maleic anhydride and water in , start stirring, slowly add urea aqueous solution under cooling, then control the material temperature, add hydrogen peroxide dropwise, heat to reflux, release carbon dioxide, and keep the temperature for several hours. After the reaction was completed, the material was released, and it was cooled to crystallize. Use a centrifuge to separate the crystals from the mother liquor, wash the crystals with water, centrifuge until the material is dry, and then place the material in a desiccator for drying. After drying, the material is cooled to room temperature to obtain a 1,2-dihydro-3,6-pyridazine dione product. The product content (HPLC) is over 98%, and the yield is 87-91%. The beneficial effects of the preparation method of the 1,2-dihydro-3,6-pyridazine dione of the present invention are: the produced product has no residual hydrazine hydrate; the whole reaction only uses water as a solvent, does not use an organic solvent and a catalyst, and also Do not use a large amount of acid and alkali, energy saving, environmental protection and safety.

Description

technical field [0001] The invention relates to a synthesis method of chemical products, in particular to a preparation method of 1,2-dihydro-3,6-pyridazinedione. Background technique [0002] The 1,2-dihydro-3,6-pyridazinedione of the following structural formula is a selective herbicide and temporary plant growth inhibitor, and can also be used as an intermediate of pesticides and medicines. [0003] [0004] The prior art related to the preparation method of 1,2-dihydro-3,6-pyridazinedione has following several kinds at present: [0005] (1) The synthetic method of Chinese patent CN101735154A, CN102108063A invention is that sulfuric acid and hydrazine hydrate are reacted to form hydrazine sulfate aqueous solution, adding organic acid as catalyst and maleic anhydride heating and reflux reaction, then neutralizing with inorganic alkali to obtain 1, 2-Dihydro-3,6-pyridazinedione. [0006] (2) The synthetic method invented by Chinese patent CN105693623A is basically the ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07D237/04
CPCC07D237/04
Inventor 杜骏
Owner SHANGHAI SHISI CHEM PROD