Method for preparing oxamide from dimethyl oxalate

A technology of dimethyl oxalate and oxamide, applied in the field of preparing oxamide, can solve problems such as unfavorable industrialization, high reaction temperature, high cost and the like

Active Publication Date: 2020-05-15
SHANGHAI WUZHENG ENG TECH CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] Preparation of oxamide mainly contains the following methods at present: 1. hydrocyanic acid method, the method synthesizes cyanogen by hydrocyanic acid, and then hydrolyzes to obtain oxamide. What this method uses is expensive and highly toxic hydrocyanic acid, which is not conducive to large-scale scale industrial production
2. Ammonium oxalate pyrolysis method, which generates oxamide by heating and dehydrating ammonium oxalate, but the step yield of ammonium oxalate dehydration to generate oxamide is low, only 30-60%, and the cost is high, which is not conducive to industrialization
At present, there are problems such as low efficiency, high reaction temperature, long reaction time, need of catalyst, and difficult separation in the synthesis method of oxalate ester ammonolysis reaction.

Method used

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  • Method for preparing oxamide from dimethyl oxalate
  • Method for preparing oxamide from dimethyl oxalate

Examples

Experimental program
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Effect test

Embodiment 1

[0055] The mixed solution of dimethyl oxalate and methanol, fresh liquid ammonia and recovered liquid ammonia enter the ammonolysis reactor 1, and the molar ratio of dimethyl oxalate, methanol and ammonia is 1:4:4. At a temperature of 60° C., an ammonolysis reaction occurs under a pressure of 0.6 MPa for a reaction time of 1 h, and an ammonolysis product stream S4 is generated. The reacted ammonolysis product stream S4 enters the solid-liquid separator 2, and the separated first solid phase stream S6 enters the drier 6. The temperature of the drier 6 is 80° C., and is dried for 6 hours to obtain the oxamide product S11. The first liquid stream S5 enters the rectifying column 3 of methanol through a pump, and the rectifying conditions are as follows: feed pressure is 0.7Mpa (G), temperature is 60°C, tower bottom pressure is 0.71Mpa (G), and temperature is 120°C ℃, the pressure at the top of the tower is 0.69Mpa (G), the temperature is 14°C, 15 trays, the reflux ratio is 0.6, th...

Embodiment 2

[0057] The mixed solution of dimethyl oxalate and methanol, fresh liquid ammonia and recovered liquid ammonia enter the ammonolysis reactor 1, and the molar ratio of dimethyl oxalate, methanol and ammonia is 1:2:4. At a temperature of 80° C., an ammonolysis reaction occurs under a pressure of 1.2 MPa for a reaction time of 0.5 h, and an ammonolysis product stream S4 is generated. The reacted ammonolysis product stream S4 enters the solid-liquid separator 2, and the separated first solid phase stream S6 is oxamide and enters the drier 6. The temperature of the drier 6 is 80° C. and dried for 6 hours. The first liquid phase stream S5 enters the rectification column 3 of methanol through a pump, and the conditions of rectification: feed pressure is 1.3Mpa (G), temperature is 100°C, tower bottom pressure is 1.31Mpa (G), temperature is 148°C , the top pressure is 1.29Mpa (G), the temperature is 34°C, 15 trays, and the reflux ratio is 0.6. The gaseous phase at the top of methanol r...

Embodiment 3

[0059]The mixed solution of dimethyl oxalate and methanol, fresh liquid ammonia and recovered liquid ammonia enter the ammonolysis reactor 1, and the molar ratio of dimethyl oxalate, methanol and ammonia is 1:4:6. At a temperature of 100° C. and a pressure of 1.0 MPa, an ammonolysis reaction occurs for a reaction time of 0.5 h, and an ammonolysis product stream S4 is generated. The reacted ammonolysis product stream S4 enters the solid-liquid separator 2, and the separated first solid phase stream S6 is oxamide and enters the drier 6. The temperature of the drier 6 is 80° C., and is dried for 6 hours to obtain the oxamide product S11. The first liquid stream S5 enters the rectification tower 3 of methanol through a pump, and the conditions of rectification: feed pressure is 1.1Mpa(G), temperature is 80°C, tower bottom pressure is 1.11Mpa(G), temperature is 140°C , the top pressure is 1.09Mpa (G), the temperature is 28°C, 15 trays, and the reflux ratio is 0.6. The gas phase at ...

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Abstract

The invention relates to a method for preparing oxamide from dimethyl oxalate, which comprises the following steps: (1) mixing a dimethyl oxalate material flow, a methanol raw material flow and a liquid ammonia material flow, and carrying out ammonolysis reaction to provide an ammonolysis product material flow; (2) performing solid-liquid separation on the ammonolysis product material flow to provide a first liquid-phase material flow and a first solid-phase material flow; (3) rectifying the first liquid-phase material flow to provide a first ammonia gas material flow and a methanol crude product material flow; condensing the first ammonia material flow to provide a first liquid ammonia recovery material flow, the first liquid ammonia recovery material flow usable for an ammonolysis reaction; refining the methanol crude product material flow to provide a methanol product material flow; (4) drying the first solid-phase material flow to provide an oxamide product and a first gas-phase material flow, and (5) performing condensation and gas-liquid separation on the first gas-phase material flow to provide a second ammonia gas material flow and a methanol recovery material flow. The method is a continuous oxamide synthesis process, methanol and ammonia can be recycled, and the method is energy-saving and environment-friendly.

Description

technical field [0001] The invention relates to the technical field of preparing oxamide, in particular to a method for preparing oxamide from dimethyl oxalate. Background technique [0002] Oxamide, also known as oxalic acid diamide, has a CAS registration number of 471-46-5. It has a molecular weight of 88.07, a nitrogen content of 31.8%, slightly soluble in water, insoluble in ethanol and ether, does not absorb moisture, has stable properties, is easy to store, and can be decomposed into ammonia and carbonic acid. It is a good high-efficiency slow-release chemical fertilizer . Compared with my country's traditional quick-acting nitrogen fertilizers (such as urea), oxamide is less volatile, insoluble in water, not easy to lose, has a high nitrogen utilization rate, and can reduce economic losses and water pollution. [0003] Preparation of oxamide mainly contains the following methods at present: 1. hydrocyanic acid method, the method synthesizes cyanogen by hydrocyanic ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C231/02C07C233/56
CPCC07C231/02C07C233/56
Inventor 王保明李玉江张辉平徐长青孙卫中
Owner SHANGHAI WUZHENG ENG TECH CO LTD
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