Process for producing methyl carbamate by low pressure solvation homogeneous phase reaction

Abstract

A process for preparing methyl aminoformate without environmental pollution includes such steps as proportionally mixing urea with methanol, reacting while supplementing the solution of urea-methanol for balancing the released ammonia-methanol vapor, purifying to obtain target product, rectifying said released vapor to obtain NH3 gas and methanol, cooling methol for recovering it, and using NH3 gas to prepare industrial ammonia water.

Description

1. Technical field [0001] The invention relates to an industrial production method for the production of fine chemicals and medicines and methyl carbamate intermediates of medicines and pesticides, belonging to the field of fine chemical production and synthesis. 2. Background technology [0002] Methyl Carbamate (MC for short), also known as Ureaghylane, is an important intermediate in organic synthesis. It is mainly used in the synthesis of medicines and pesticides. Its derivatives are used as herbicides, insecticides, rubber antioxidants, heat stabilizers, etc., and are more and more widely used in agriculture and rubber industries. Carbamate pesticides, compared with other kinds of pesticides, have the characteristics of low toxicity to humans and other mammals, strong specificity in poisoning, easy to be degraded by various factors, low residues, and small side effects on the environment. Therefore, in recent years, it has become a new type of insecticide, herbicide, m...

AI Technical Summary

Problems solved by technology

At present, there are roughly three types of methods for producing MC from urea and methanol at home and abroad. One is the catalytic synthesis method at normal temperature and pressure. This method introduces inorganic acid as a catalyst. The reaction time is as long as 35h, and the yield is only 40% (in urea). And there is serious corrosion to equipment, the product is difficult to refine etc. problem; The 2nd, high temperature and high pressure synthesis method, although the time of this kind of reaction is shortened greatly, also does not have equipment corrosion problem, but reaction temperature is very high, and reaction pressure reaches dozens of MPa, yield The rate is less than 40%, and a large amount of urea is lost due to decomposition

This type of reaction was adopted abroad in the 1950s and 1960s (the current domestic urea alcoholysis method adopts this method); the third is the medium temperature and medium pressure catalytic synthesis method, which is a new method developed abroad in the 1970s. , pressure and reaction time are all moderate, and the yield is not low, but the catalyst used in the reaction is an oxide or salt of a transition metal and H 2 SO 4 、HNO 3 、H 3 PO 4 And the compound of inorganic acid such as polyphosphoric acid still has the problem of corrosion to equipment

At the beginning of the 21st century, some researchers experimented with the method of synthesizing MC by using ion exchange resin plus a small amount of zinc oxide as a catalyst. The temperature was about 140°C and the pressure was about 2.0Mpa. The problem is that the multi-phase catalysis requires complex equipment, and the second is that the catalyst used has a short service life and is difficult to regenerate