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Environment-friendly polyisocyanate synthesis method suitable for industrial production

A polyisocyanate and dihydrooxime technology, applied in the field of isocyanate, can solve the problems of slow reaction rate, high price, and many side reactions

Inactive Publication Date: 2020-06-26
CHANGCHUN INST OF APPLIED CHEMISTRY - CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The triphosgene method uses solid triphosgene instead of phosgene to prepare MDI. Although it has the advantages of convenient use, solid weighing, mild reaction conditions, and high yield, when the solid triphosgene method is used, a large amount of hydrochloric acid will still be produced, which will corrode the equipment. The problem of chloride in the product has not been solved
In the second step of thermal decomposition, although carbamate can be decomposed to generate isocyanate at high temperature, the reaction rate is slow and there are many side reactions, which is not conducive to industrial production. Therefore, it is necessary to introduce a catalyst in the reaction process to improve efficiency. , most of these catalysts are Group VIII metals, which are not only expensive but also easily deactivated at high temperatures. Even if there are cheap catalysts to choose from in individual methods, the recovery and separation of catalysts also increases economic costs and energy consumption. Therefore, the industrial application of this method is limited

Method used

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  • Environment-friendly polyisocyanate synthesis method suitable for industrial production
  • Environment-friendly polyisocyanate synthesis method suitable for industrial production
  • Environment-friendly polyisocyanate synthesis method suitable for industrial production

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0054] In a 2L three-necked flask, dissolve 0.135mol of ethyl terephthalate in 400ml of methanol at room temperature; dissolve 0.81mol of sodium hydroxide in 90ml of distilled water, and dissolve 0.81mol of hydroxylamine hydrochloride in 60ml of distilled water, and mix Two alkaline solutions were added dropwise to the terephthalate solution at 5°C, then the reactant was stirred at 55°C for 72 hours; the above mixture was neutralized to pH with 700ml of 5% hydrochloric acid to 6-7, then filter the solution, and stir the solid obtained in 1L boiling methanol; afterward, the mixture is filtered to obtain white solid terephthalic acid, the yield of the reaction is 92%, and the purity of the product can Reached 97%.

[0055] figure 1 Be the H-NMR spectrogram of p-phthalic dihydroxamic acid in the embodiment of the present invention 1; By figure 1 It can be seen that the single peak 7.8ppm corresponds to 4H C-H aromatic compound, the single peak 9.1ppm corresponds to 2HO-H, and t...

Embodiment 2

[0059] In a 2L three-necked flask, 0.135mol of ethyl toluate was dissolved in 400ml of methanol at room temperature; 0.81mol of sodium hydroxide was dissolved in 90ml of distilled water, and hydroxylamine hydrochloride was dissolved in 60ml of distilled water. solution, and added dropwise to the terephthalate solution at 5°C, and then the reactant was stirred at 55°C for 72 hours; the above mixture was neutralized to pH 6-7 with 700ml of 5% hydrochloric acid , Then the solution was filtered, and the obtained solid was stirred in 1L of boiling methanol; after that, the mixture was filtered to obtain a white solid dihydroxamic acid, the yield of the reaction was 93%, and the purity of the product reached 97%.

[0060] Weigh a certain mass of the white solid dihydroxamic acid obtained above, add 2 times the equivalent of 4-nitrobenzenesulfonyl chloride and 4 times the equivalent of triethylamine, all dissolved in excess tetrahydrofuran, at 0-25 After fully stirring at ℃ for 6 hou...

Embodiment 3

[0065] In a 2L three-necked flask, 0.135mol of ethyl diphenylmethane dicarboxylate was dissolved in 400ml of methanol at room temperature; 0.81mol of sodium hydroxide was dissolved in 90ml of distilled water, and hydroxylamine hydrochloride was dissolved in 60ml of distilled water. An alkaline solution was added dropwise to the terephthalate solution at 5°C, and the reactant was stirred at 55°C for 72 hours; the above mixture was neutralized to pH 6 with 700ml of 5% hydrochloric acid -7, then filter the solution, and stir the obtained solid in 1 L of boiling methanol. Afterwards, the mixture was filtered to obtain white solid dihydroxamic acid, the yield of the reaction was 92%, and the purity of the product could reach 98%.

[0066] Weigh a certain mass of the white solid dihydroxamic acid obtained above, add 2 times the equivalent of 4-nitrobenzenesulfonyl chloride and 4 times the equivalent of triethylamine, all dissolved in excess tetrahydrofuran, at 0-25 After fully stir...

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Abstract

The invention provides a method for synthesizing polyisocyanate. The method comprises the following steps: carrying out a reaction on R1OOC-R-COOR1 in the presence of NaOH and NH2HCl, and neutralizingto obtain dihydroxamic acid HO-NH-CO-R-CO-NH-OH, wherein R1 is selected from C1-C15 aliphatic alkyl, and R is selected from one or more of phenylene, substituent-containing C6-C30 arylene, unsubstituted C6-C30 arylene, C6-C20 sub-aliphatic hydrocarbon group, C6-C20 cycloaliphatic hydrocarbon group and a naphthylene group; and rearranging the dihydroxamic acid under an alkaline condition to obtainthe polyisocyanate OCN-R-NCO. According to the method, highly toxic gases are not adopted, corrosive gases or intermediates are not generated in the reaction process, and noble metal catalysts are not needed, so that the method is environment-friendly and simple, the product selectivity in the reaction process is good, side reactions are few, and the yield is high.

Description

technical field [0001] The invention belongs to the technical field of isocyanates, and in particular relates to a green method for synthesizing polyisocyanates suitable for industrial production. Background technique [0002] Isocyanate, especially diisocyanate, such as methylene diphenyl diisocyanate (MDI), toluene diisocyanate (TDI), 1,6-hexamethylene diisocyanate (HDI), etc. are important raw materials for the production of polyurethane in our society. At present, the output of isocyanate in the world is close to 10 million tons, and industrial isocyanate is mainly synthesized by phosgene method. Although the technology is mature, the phosgene used is volatile, highly toxic, highly polluting to the environment, consumes a lot of energy, and the hydrogen chloride produced seriously corrodes the equipment, resulting in high cost of production equipment, complicated technical requirements, and high chloride ion impurities in the product. Difficult to remove from the purifi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C265/14C07C263/12
CPCC07C259/10C07C263/12C07C265/14
Inventor 冉祥海高一星聂伟
Owner CHANGCHUN INST OF APPLIED CHEMISTRY - CHINESE ACAD OF SCI
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