Process for synthesizing biurea by adopting semicarbazide

Abstract

The invention provides a process for synthesizing biurea by adopting semicarbazide. The process comprises the following steps: a, using semicarbazide and cyanate as raw materials, weighing solid according to the molar ratio of semicarbazide to cyanic acid radicals of 1: (1.01 to 1.05) and adding water; b, keeping the temperature of the mixed solution in a range of 0 to 80 DEG C; c, preparing an acid solution according to the molar ratio of the cyanic acid radical to H+ being 1: (1.01 to 1.05); d, dropwise adding the acid solution into the mixed solution while stirring, and finishing the reaction; and e, filtering, washing and drying. The process has the beneficial effects that firstly, a low temperature is adopted in the reaction, the semicarbazide is stable in property, is difficult to volatilize and is difficult to convert into other substances, the conversion rate is very high, and the yield of 100% can be reached; secondly, a reaction byproduct is sodium salt, has no pollution to the environment, and can be discharged without being post-processed; thirdly, the reaction is performed under a normal pressure and is easy to operate; and fourthly, the acidity is low in the reaction and the equipment is corroded a little.

Description

technical field [0001] The invention relates to the field of biurea synthesis, in particular to a process for synthesizing biurea by using semicarbazide. Background technique [0002] The chemical name of biurea is hydrazine dicarboxamide, the molecular formula is C2H6N4O2, the chemical formula is H2NCONH-NHCONH2, and the relative molecular mass is 118. It is mainly used in the production of ADC foaming agent (azodicarbonamide), and can also be used in the anti-skid of airstrips, high-grade highways, gears, and fire-proof and anti-melt of high-grade cables. [0003] Biurea is usually formed by the condensation reaction of hydrazine hydrate and urea under acidic conditions. This process produces biurea, and the reaction temperature is relatively high. Generally, the condensation reaction is carried out at 105-120°C to obtain the product biurea and ammonium salt. The by-product ammonium salt needs to be further evaporated and concentrated to recover ammonia. Due to the high ...

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Problems solved by technology

Due to the high temperature required for the reaction, urea is easily decomposed to produce a large number of by-products during the reaction, so the amount of urea added is greatly excessive, the product yield is low, and the utilization rate of raw materials is low

Biurea can also be formed by direct condensation of urea and hydrazine hydrate, but the reaction time is longer, and the reaction needs to be carried out at 105-120°C. The by-product of the reaction is ammonia gas, and the subsequent input of ammonia recovery will increase the cost.

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