Maleic hydrazide synthetic process

Abstract

A maleic hydrazide synthetic process comprises the steps of 1, adding maleic anhydride and an organic solvent into a reaction still, and conducting stirring to enable maleic anhydride and the organic solvent to be fully dissolved; 2, adding acid, water and hydrazine hydrate for temperate-controlled reaction; 3, steaming out the organic solvent through heating reflux, and recovering the organic solvent at the same time; 4, conducting heating reflux reaction again; 5, conducting cooling filtration, and recycling filtrate as water phase; 6, conducting recrystallization on filter cakes with the recovered organic solvent, obtaining maleic hydrazide through filtration, and recyling mother liquor, namely the organic solvent; 7, drying and packing maleic hydrazide. Compared with the prior art, the process has the advantages that the consumption of hydrazine hydrate is low (below 20%), production cost is low, and the residual amount of highly toxic hydrazine hydrate is small (smaller than 1 PPm).

Description

technical field

[0001] The invention relates to a synthesis process of maleic hydrazide. Background technique

[0002] Maleic hydrazide, also known as 3,6-dihydroxypyridazine or maleic acid hydrazide, is a plant growth regulator and also has a variety of biological activities, such as herbicidal, bactericidal, and antiviral effects. At the same time, it is an important synthetic intermediate in the pesticide and pharmaceutical synthesis industry.

[0003] The traditional synthesis process is to add water and hydrazine hydrate into the reaction kettle, add inorganic acid dropwise under stirring and cooling, control the temperature below 30°C, adjust the pH value to 5.3-6.7, put in maleic anhydride, and heat up and reflux for 5 hours Afterwards, cool down to below 10°C, filter, wash the filter cake with water, and dry it. The yield is usually 84-90%. This production process will produce 4-5 tons of organic wastewater containing strong acid for every ton of product produced. ...

Examples

Embodiment 1

[0012] Add 380Kg of organic solvent and 98 Kg of maleic anhydride to a 1000L reactor, add water to dilute after stirring, then add 130Kg of 40% hydrazine hydrate, control the temperature below 30°C, react for 2 hours, add 30Kg of acid as a catalyst, and slowly heat up to 50 ℃, keep warm for 2 hours, heat up and reflux for 2 hours, evaporate the organic solvent, then raise the temperature to 100-104°C, reflux for 1 to 3 hours, cool down to below 10°C, filter, wash once with ice water, and reuse the filtrate as the water phase. The filter cake was recrystallized with the organic solvent recovered above to obtain 102 Kg of maleic hydrazide, with a yield of 91% (the yield of the mother liquor was increased by applying the method) and a purity of 99.2%.

technical field

[0001] The invention relates to a synthesis process of maleic hydrazide. Background technique

[0002] Maleic hydrazide, also known as 3,6-dihydroxypyridazine or maleic acid hydrazide, is a plant growth regulator and also has a variety of biological activities, such as herbicidal, bactericidal, and antiviral effects. At the same time, it is an important synthetic intermediate in the pesticide and pharmaceutical synthesis industry.

[0003] The traditional synthesis process is to add water and hydrazine hydrate into the reaction kettle, add inorganic acid dropwise under stirring and cooling, control the temperature below 30°C, adjust the pH value to 5.3-6.7, put in maleic anhydride, and heat up and reflux for 5 hours Afterwards, cool down to below 10°C, filter, wash the filter cake with water, and dry it. The yield is usually 84-90%. This production process will produce 4-5 tons of organic wastewater containing strong acid for every ton of product produced. ...

Examples

Embodiment 1

[0012] Add 380Kg of organic solvent and 98 Kg of maleic anhydride to a 1000L reactor, add water to dilute after stirring, then add 130Kg of 40% hydrazine hydrate, control the temperature below 30°C, react for 2 hours, add 30Kg of acid as a catalyst, and slowly heat up to 50 ℃, keep warm for 2 hours, heat up and reflux for 2 hours, evaporate the organic solvent, then raise the temperature to 100-104°C, reflux for 1 to 3 hours, cool down to below 10°C, filter, wash once with ice water, and reuse the filtrate as the water phase. The filter cake was recrystallized with the organic solvent recovered above to obtain 102 Kg of maleic hydrazide, with a yield of 91% (the yield of the mother liquor was increased by applying the method) and a purity of 99.2%.