Preparation method of substituted 1,4-phenylene diisocyanate and application of non-nitrile polar organic solvent in preparation of substituted 1,4-phenylene diisocyanate

Abstract

The invention belongs to the technical field of fine chemical engineering, and particularly relates to a preparation method of substituted 1,4-phenylene diisocyanate and an application of a non-nitrile polar organic solvent in preparation of the substituted 1,4-phenylene diisocyanate. The non-nitrile polar organic solvent provided by the invention is used as a reaction solvent for preparing the substituted 1,4-phenylene diisocyanate, and solid diamine (or hydrochloride thereof) continuously dissolves in the solvent system, the contact time and contact area of the diamine (or hydrochloride thereof) with phosgene are reduced, and gasification the solid diamine is not needed, so that the equipment structure is simplified, and production cost is reduced. Distribution of the dissolved diamine (or hydrochloride thereof) in the system is approximately equal to distribution of the residence time of the phosgene, and the process is controllable. According to the preparation method of the substituted 1,4-phenylene diisocyanate provided by the invention, the non-nitrile polar organic solvent system is adopted, so that generation of a large amount of wastewater is avoided, pollution to the environment is reduced, meanwhile, loss of substituted 1,4-phenylenediamine hydrochloride during filtration operation is reduced, and the yield is improved.

Description

technical field [0001] The invention belongs to the technical field of fine chemicals, and in particular relates to a preparation method of substituted p-phenylene diisocyanate and the application of non-nitrile polar organic solvents in the preparation. Background technique [0002] As a chemical intermediate, p-phenylene diisocyanate is widely used. The compound first uses p-phenylenediamine as the starting material, water as the reaction solvent, reacts with hydrochloric acid to generate p-phenylenediamine hydrochloride; then reacts p-phenylenediamine hydrochloride with phosgene to obtain p-phenylenediisocyanate . [0003] P-phenylene diisocyanate is the simplest aromatic diisocyanate in structure. With the continuous development of diisocyanate varieties, substituted p-phenylene diisocyanate (such as the H on the benzene ring is replaced by other groups) has been favored due to its better performance. People pay attention. If the substituted p-phenylenediamine is used...

AI Technical Summary

Problems solved by technology

[0004] Therefore, the technical problem to be solved in the present invention is to overcome the defects of the existing preparation method of substituted p-phenylene diisocyanate in terms of purity, unstable yield, large amount of waste water and cumbersome steps, thereby providing a kind of anhydrous participation, high yield, High-purity preparation method and novel reaction solvent suitable for the preparation method

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