A kind of defoaming method of amide compound and phosgene reaction system

Abstract

The invention discloses a defoaming method for the reaction system of amide compounds and phosgene. The defoaming method uses polytrifluoropropylmethylsiloxane as a defoaming agent to defoam the reaction system of amide compounds and phosgene. bubble treatment. In the defoaming method of the present invention, polytrifluoropropylmethylsiloxane is used as the defoaming agent, which can accelerate the dissolution and dispersion of the foam produced in the reaction process, does not require special reaction equipment, and can effectively eliminate the foam in the reaction system in time. Foam, with the advantages of fast defoaming speed and good defoaming effect, solves the foaming problem of the reaction system of amide compounds and phosgene, greatly improves the feeding coefficient of the reaction system of amide compounds and phosgene, and ensures a higher reaction On the basis of the yield and product purity, the reaction rate is accelerated, so that the production capacity is greatly increased, which is beneficial to industrial production, and has good application value and application prospect.

Description

technical field [0001] The invention relates to a reaction of amide compounds and phosgene, in particular to a defoaming method for a reaction system of amide compounds and phosgene. Background technique [0002] The reaction between amide compounds and phosgene generally involves nucleophilic substitution between the chlorocarbonyl group and the substrate, and further elimination of carbon dioxide and hydrogen chloride to form the corresponding nitrile or isonitrile. The reaction mechanism is as follows. [0003] [0004] There are many methods for preparing nitriles or isonitriles, and the method of using phosgene to react with amides is the most commonly used method. When using amide compounds and phosgene to react to prepare nitriles, a molecule of phosgene is introduced to react, and then in the reaction process, one molecule of carbon dioxide will be removed first, and then two molecules of hydrogen chloride will be removed. The raw material gas, and a large amount...

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Problems solved by technology

In response to the above problems, the researchers operated with the phosgene feed rate designed according to the optimized conditions to prevent material overflow, but at this time the feeding coefficient can only be set below 0.3 of the reactor, which seriously reduces the production capacity

At the same time, in the preparation process, the researchers solved the problem of foaming and phosgene flow limitation by improving the form of the reactor and installing a defoamer. However, the defoamer needs to be accurately calculated and specifically designed. The defoamer should have a very large volume under the conditions of speed and material feeding volume, which is not conducive to industrial production

In addition, in the process of preparing isonitriles using amide compounds and phosgene, although trialkylamines are generally used as acid-binding agents to remove the generated hydrogen chloride and generate trialkylamine hydrochloride, but in the post-treatment distillation heating process , the concentration of trialkylamine hydrochloride is relatively high, hydrogen chloride gas will be re-released to form foam, and there is physical foaming phenomenon in the heating process of hydrochloride, which will also produce a large amount of foam, which is not conducive to the purification of the product, so as not to Conducive to improving the reaction yield and product purity

In addition, the use of amide compounds to react with phosgene, this type of reaction has many transition states, is easy to generate by-products, and the reaction is very sensitive to foreign matter, such as the addition of a small amount of impurities such as rust or viscous oil will cause the transition state molecules of the reaction to generate by-products , thus seriously affecting the reaction yield and product purity

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