Preparation method of N-phenylmaleimide (PMI)

Abstract

The invention provides a preparation method of N-phenylmaleimide (PMI). The preparation method comprises the following steps of: mixing and stirring a catalyst, an organic solvent, a polymerization inhibitor and maleic anhydride (MA) into a reaction kettle, and carrying out heat treatment on the mixture at the first reaction temperature for a first reaction time to form an MA mixture; then, continuously adding aniline into the heat-treated MA mixture in quantity, meanwhile, reflowing and dehydrating, and carrying out acid base neutralization; and layering, washing, cooling and crystallizing to obtain the N-PMI with high yield and purity.

Description

technical field [0001] The present invention relates to a method for preparing N-phenylmaleimide (N-phenylmaleimide, PMI), especially a method for preparing high-yield and high-purity N-phenylmaleimide . Background technique [0002] N-phenylmaleimide (PMI) is a raw material for organic synthesis, which can be embedded in polymer chains to increase the internal rotation resistance between chains, thereby improving the heat resistance of materials. At present, N-phenylmaleimide is often used as a heat-resistant modifier of acrylonitrile-butadiene-styrene resin (acrylonitrile butadiene styrene resin, ABS resin), which can improve the performance of acrylonitrile-butadiene-styrene resin. The softening point can improve its heat resistance, and the modified acrylonitrile-butadiene-styrene resin is impact-resistant, so it can replace some engineering plastics and can be used in the automotive industry. In addition, N-phenylmaleimide can also be used as a polypropylene (polyprop...

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Problems solved by technology

[0003] The N-phenylmaleimide of the prior art is synthesized by maleic anhydride (maleic anhydride, MA) and aniline (aniline), but the manufacturing process is complicated, and the yield is low and the purity is not high, for example China Taiwan Invention Patent No. 29955 discloses the use of ammonium salt as a catalyst to prepare N-phenylmaleimide, but the reaction is difficult due to poor solubility, and metal compounds must be added during the manufacturing process, making the process cost higher; the United States Patent No. 5136052 discloses that aniline, maleic anhydride and organic acid are mixed and then filtered to remove catalyst and impurities, wherein the filtration step is quite troublesome; other documents point out that in the presence of catalyst, N-phenylmaleic acid N-phenylmaleamic acid (N-phenylmaleamic acid) reacts with oxalyl chloride to produce hydrochloric acid (hydrochloric acid). This method not only has a poor yield, but also requires reprocessing of its by-product hydrochloric acid, so the process is relatively complicated; Others also have literature to point out, first add alcohol to N-phenylmaleimide acid and carry out esterification in the presence of sulfuric acid, then add phosphoric acid to dealcoholize to produce N-phenylmaleimide, the process The sulfuric acid used is strong in acidity, and after alcohol addition and esterification, de-alcoholization is also not in line with commercial value; in addition, China Taiwan Invention Patent No. 225859 also discloses a synthetic method of N-phenylmaleimide, but the The method needs to be heated to 50°C, and then heated to 140°C for reflux dehydration, and the temperature needs to be cooled and filtered, so this method is time-consuming and energy-consuming

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