Method for preparing xylylene diisocyanate based on salification-phosgenation reaction

A technology for xylylenediamine hydrochloride and salt-forming reaction, which is applied in chemical instruments and methods, preparation of organic compounds, preparation of isocyanic acid derivatives, etc. The problem of incomplete salt formation of base diamine and low space-time conversion rate of photochemical reaction can achieve the effect of suppressing by-products.

Active Publication Date: 2011-05-25
WANHUA CHEM GRP CO LTD +1
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Problems solved by technology

[0014] In order to overcome the excessive viscosity of high-concentration xylylenediamine hydrochloride solution in the salt-forming process of existing xylylenediisocyanate, resulting in incomplete salification of xylylenediamine, many side reactions, benzene The problem of low space-time conversion rate of photochemical reaction at low concentration of dimethylenediamine hydrochloride

Method used

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  • Method for preparing xylylene diisocyanate based on salification-phosgenation reaction

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Embodiment 1

[0045] In this method, the salt-forming reaction adopts a continuous mode, and the phosgenation reaction adopts a batch mode. A reactor with a jet reactor and stirring was used as a salt-forming reactor with a volume of 1000 milliliters, and 414 g of o-dichlorobenzene was charged in advance as a reaction solvent. The volume of the phosgenation reactor is 5 liters. 681g (5 moles) of m-xylylenediamine and 2724g of o-dichlorobenzene (total amine concentration of feed is 20wt%) were put into the raw material tank to form m-xylylenediamine solution (or called reaction solution). The temperature of the reaction solution was maintained at 30°C by means of external cooling. The hydrogen chloride gas is passed into the gas phase nozzle of the jet reactor through a high-pressure pump, and the feeding speed of hydrogen chloride is 7.8L / min, and the m-xylylenediamine solution is passed into with a feed pump at a speed of 56.4g / min. The liquid phase nozzle of the jet reactor, m-xylylened...

Embodiment 2

[0047] In this embodiment, the same reactor as in Embodiment 1 was used, and 414 g of o-dichlorobenzene was pre-loaded in the salt-forming reactor as a reaction solvent. The volume of the phosgenation reactor is 5 liters. Drop into 480.7g (3.53 moles) m-xylylenediamine and 2724g o-dichlorobenzene (feeding total amine concentration is 15wt%) in raw material tank to form m-xylylenediamine solution (or called reaction solution) . The temperature of the reaction solution was kept at 30°C by means of external cooling. The hydrogen chloride gas is passed into the gas phase nozzle of the jet reactor through a high-pressure pump, and the feeding speed of hydrogen chloride is 5.8L / min, and the m-xylylenediamine solution is passed into with a feed pump at a speed of 56.4g / min. The liquid phase nozzle of the jet reactor, m-xylylenediamine solution and hydrogen chloride are mixed and reacted in the jet reactor and enter into the salt-forming reactor. After the concentration of the hydr...

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Abstract

The invention discloses a method for preparing xylylene diisocyanate (XDI) based on salification-phosgenation reaction. The method comprises the following steps of: (a) a salification reaction process of amine solution which is formed by xylylene diamine in an inert organic solvent and hydrogen chloride; (b) a hydrochloride centrifugal concentration process; (c) a high-pressure phosgenation process; and (d) a low-pressure phosgenation process. In the method, the salification reaction of the amine is kept performing in low-concentration hydrochloride solution all the time; and high-concentration hydrochloride solution participates in the phosgenation reaction to prepare the XDI. The process has a high time-space conversion rate and simultaneously ensures a good salification effect.

Description

technical field [0001] The invention relates to a preparation method of xylylene diisocyanate, in particular to a method for preparing xylylene diisocyanate (XDI) based on a salt-forming phosgenation reaction. Background technique [0002] Xylylene diisocyanate (XDI), the chemical structure is: [0003] [0004] The relative molecular weight is 188.19, and it is a colorless transparent liquid at room temperature. The melting point is 7.5-12°C. XDI (mixture of isomers) is a colorless transparent liquid at room temperature with a boiling point of 151°C (800Pa). Density 1.202g / cm 3 (20°C). Viscosity 3.6mPa·s (20°C). The refractive index is 1.429. The flash point is 185°C. XDI has low vapor pressure and high reactivity. Since the isocyanate group in the molecular structure is not directly connected to the benzene ring but is separated by methylene (-CH2-), the resonance phenomenon between the benzene ring and the isocyanate group is prevented, making XDI and its polyu...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C265/14C07C263/10
Inventor 丁建生石滨尚永华孙中平于天杰张颜涛王志刚陈明森华卫琦
Owner WANHUA CHEM GRP CO LTD
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