Process for purifying methyl carbamate

The technology of methyl carbamate and distillation kettle is applied in the preparation of carbamate derivatives, chemical instruments and methods, preparation of organic compounds, etc., and can solve the problems of mixture agglomeration, loss, energy consumption and output loss, etc.

Inactive Publication Date: 2005-10-19
山东康瑞集团有限公司 +1
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Problems solved by technology

[0003] No matter what method is used to synthesize methyl carbamate, because there are reactants, by-products and catalysts in the reactor liquid, after heating, the viscosity of the eutectic system is very large. During ordinary distillation and direct vacuum distillation, the product steam The escaping speed is very slow, heating for a long time will easily cause multi-component polymerization and agglomeration of the mixture, and the loss of product MC is as high as 30%.
Therefore, the energy consumption and output loss of the existing various purification methods are too large, and the cost is very high

Method used

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Embodiment 2

[0010] Use urea and methanol as the raw material to react the reaction liquid, after distilling the methanol at normal pressure in the reaction kettle, keep the reaction liquid at 70-100°C in the reaction kettle, for 5m 3 Vacuum distillation kettle, the above reaction solution is prepared 3.0 ~ 3.5m 3 , close the decompression system, start the vacuum pump, control the system pressure at 0.03Mpa, use the material transfer pump to spray it into the vacuum distillation kettle at a constant speed of 12L / min, after 8min, slowly open the dry hot air intake control valve, And control the gas temperature to 80 ~ 100 ℃, maintain the system pressure (0.020Mpa). At this time, the methyl carbamate is condensed into a liquid in the gas phase after cooling (cooling temperature 56-60° C.), and collected in the product. The reaction solution was added within 25 min, and the valve was closed. The recovery rate of methyl carbamate thus obtained is 97%, and the content of methyl carbamate is ...

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Abstract

The methyl carbamate purifying process belongs to the field of fine chemical technology. The technological scheme of purifying methyl carbamate includes: spraying methyl carbamate solution into decompression distiller, spraying dewatered and heated gas into the decompression distiller in the direction opposite to that of the methyl carbamate solution to increase the gas-liquid contact area, maintaining the decompression distiller at 60-150 deg.c temperature and 0.001-0.1 MPa pressure, cooling the distilled gaseous methyl carbamate and separating. The methyl carbamate solution into the decompression distiller has temperature controlled in 70-100 deg.c, and the gas into the decompression distiller has temperature controlled in 80-100 deg.c and lagged entering time, and the distilled gaseous methyl carbamate has cooling temperature controlled in 56-60 deg.c. The process has short separation time, low power consumption, high product yield, and product purity over 95 %.

Description

1. Technical field [0001] The invention relates to a method for purifying methyl carbamate by vacuum gas stripping and distillation, which belongs to the field of fine chemical purification. 2. Background technology [0002] Methyl Carbamate (MC for short), also known as Ureathylane and Methylurethane, is an important intermediate in organic synthesis. The structural formula is NH 2 COOCH 3 , with a molar mass of 75.07. The pure product is white needle crystal, soluble in water and ethanol, soluble in ether. The melting point is 54°C, the boiling point is 177°C, the relative density is 1.1361 (56 / 4°C), and the refractive index is 1.4125 (56°C). Generally, the synthesis of medicines and pesticides requires that the MC content in the product is 98.5%. At this time, it is white or milky white granular crystal, with a melting point of 52-54°C and a boiling point of about 177°C. See water break down faster. Therefore, establishing a reasonable purification method to avoid m...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C269/08C07C271/12
Inventor 张兆文袁存光于剑峰唐仕明袁建国张延路
Owner 山东康瑞集团有限公司
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