Method for purifying N-phenylmaleimide

A technology for maleimide and crude maleimide, which is applied in the field of fine chemicals, can solve the problems of long process, low yield, increased solvent emissions, etc., and achieve improved product yield, high product purity, and reduced The effect of production costs

Inactive Publication Date: 2018-10-09
Z RIVER GRP LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] In patent CN102633706A, the temperature of the reaction solution is lowered to -5-0°C, and the crude product is obtained by suction filtration, and then the crude product is added to the solvent, and then clay and acid-binding agent are added, dissolved by heating, filtered, cooled, crystallized, and dried to obtain a fine product with a purity of 99.12%-99.18%, longer process, lower yield, increased solvent emissions

Method used

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Examples

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preparation example Construction

[0032] The preparation method of N-phenylmaleimide crude product:

[0033] At room temperature, add 120ml of toluene (including the previous fraction obtained from the previous distillation process) and 0.05mol N,N-dimethylformamide to a 250ml four-necked flask containing 0.1mol maleic anhydride in sequence, stir well and then add dropwise 0.1mol aniline, acylation reaction at 60-70°C for 2.5h after the dropwise addition, to obtain the intermediate product N-phenylmaleimide acid; continue to heat up, add 8ml catalyst phosphoric acid, and carry out cyclization under toluene reflux Dehydration, the cyclization reaction time is 3h, the temperature of the cyclization reaction is 115-120°C, after the dehydration reaction is completed, the temperature is lowered to below 70°C, the reaction solution is washed with water, and the toluene solvent is removed by normal pressure distillation to obtain N-benzene crude maleimide. In this crude product, the purity of N-phenylmaleimide is on...

Embodiment 1

[0035] Embodiment 1, a kind of purification method of N-phenylmaleimide, take N-phenylmaleimide crude product as raw material, carry out the following steps successively:

[0036] Select the distillation kettle with copper block inlaid inside for use, transfer the N-phenylmaleimide crude product of 0.1kg (about 0.58mol) in the above-mentioned distillation kettle, start the vacuum pump, guarantee the absolute pressure of the system (the absolute pressure in the distillation kettle ) is stable at 1.0kPa; start stirring.

[0037] First, the temperature was raised to 100° C. for the first vacuum distillation to obtain the previous fraction; the previous fraction was used in the next round of synthesis (that is, the previous fraction can be used as the reaction raw material for the preparation of crude N-phenylmaleimide).

[0038] When there is no liquid reflux in the distillation kettle under the first vacuum distillation condition, replace the receiving bottle, heat up to 120°C a...

Embodiment 2

[0042] Embodiment 2, the temperature of underpressure distillation is changed from 100 DEG C to 90 DEG C for the first time, and all the other are equal to Embodiment 1. The obtained results are: the total yield of the product is 92.5%, the product purity is 99.0%, and the product is bright yellow; it is a flaky crystal of 0.02-0.03 mm.

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PUM

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Abstract

The invention discloses a method for purifying N-phenylmaleimide. The method utilizes an N-phenylmaleimide crude product as a raw material and comprises selecting a distillation kettle with an inner copper block, transferring the N-phenylmaleimide crude product into the distillation kettle, setting kettle pressure of less than or equal to 1.5kPa, heating the N-phenylmaleimide crude product to 90-110 DEG C, carrying out primary vacuum distillation to obtain a front fraction, replacing a receiving bottle when there is no liquid reflux in the distillation kettle under the primary vacuum distillation condition, carrying out heating to 110-130 DEG C, carrying out secondary vacuum distillation to obtain an N-phenylmaleimide fraction, and stopping distillation when there is no liquid reflux in the distillation kettle under the secondary vacuum distillation. The method is free of additives, prevents new impurities, produces a high purity product and has a high yield.

Description

technical field [0001] The invention belongs to the field of fine chemicals, and relates to a method for purifying N-phenylmaleimide—a process for purifying crude N-phenylmaleimide by vacuum distillation. Background technique [0002] N-phenylmaleimide is a five-membered cyclic monomer with a 1,2-disubstituted vinyl structure. Embedding it in a polymer chain can increase the internal rotation resistance of the chain, thereby improving the polymer heat resistance. Therefore, it is mainly used as a heat-resistant modifier for resins such as ABS, PVC, and PMMA. While significantly improving the heat resistance of the material, it can greatly improve the impact resistance, heat-meltability, and processability of the material. At present, the product purity in domestic industrial production is only about 97%, while the purity of imported products reaches 98%, and domestic products have problems such as impure color and short shelf life. [0003] The main reason for the low puri...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D207/448
CPCC07D207/448
Inventor 张琪阮诗想张超张华
Owner Z RIVER GRP LTD
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