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A method for purifying ethyl xylylene dicarbamate by melt crystallization

A technology for purifying ethyl xylylene dicarbamate and ethyl xylylene dicarbamate, which is applied in the field of melting crystallization and purifying ethyl xylylene dicarbamate, and can solve separation problems and the like problem, to achieve the effect of simple equipment

Active Publication Date: 2022-05-24
INST OF PROCESS ENG CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In the carbamate synthesis section of xylylenediamine (XDA) through carbonylation, excess carbonylating agent ethyl carbamate reacts with m-xylylenediamine to generate xylylene dicarbamate (XDC), and then There is a problem with the separation of ethyl carbamate and ethyl xylylenedicarbamate

Method used

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  • A method for purifying ethyl xylylene dicarbamate by melt crystallization
  • A method for purifying ethyl xylylene dicarbamate by melt crystallization

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0035] The present embodiment provides a method for purifying xylylenedicarbamate by melt crystallization, the method comprising the following steps:

[0036] (1) 125 g crude xylylenedicarbamate (containing 90.62 wt% of xylylenedicarbamate and 9.38 wt% of urethane) was placed in a static melt crystallizer , the temperature was raised to 93 °C and kept for 30 min to obtain a mixture;

[0037] (2) Cool the mixture obtained in step (1) from 93°C to 85°C at a cooling rate of 3°C / h, and after constant temperature for 30 min, use a water pump to extract the liquid in the crystallizer to obtain xylylenediamino ethyl formate crude crystal;

[0038] (3) The crude crystals of ethyl xylylenedicarbamate obtained in step (2) were heated to 101°C at a heating rate of 3°C / h, and the perspiration liquid was discharged from the outlet at the bottom of the crystallizer to obtain xylylene. pure ethyl dicarbamate;

[0039] (4) The pure ethyl xylylenedicarbamate obtained in step (3) was raised ...

Embodiment 2

[0041] (1) 125 g crude xylylenedicarbamate (containing 90.25 wt% of xylylenedicarbamate and 9.75 wt% of urethane) was placed in a static melt crystallizer , the temperature was raised to 94 °C and kept for 32 min to obtain a mixture;

[0042] (2) Cool the mixture obtained in step (1) from 94°C to 88°C at a cooling rate of 4°C / h, and after constant temperature for 34 min, use a water pump to extract the liquid in the crystallizer to obtain xylylenediamino ethyl formate crude crystal;

[0043](3) The crude ethyl xylylenedicarbamate crystal obtained in step (2) is heated to 100°C at a heating rate of 5°C / h, and the perspiration liquid is discharged from the outlet at the bottom of the crystallizer to obtain xylylene. pure ethyl dicarbamate;

[0044] (4) The pure ethyl xylylenedicarbamate obtained in step (3) was raised to 107°C, all the crystals in the crystallizer were melted and discharged from the bottom of the crystallizer. After weighing, 67.19 g of the product was obtain...

Embodiment 3

[0046] (1) 125 g crude xylylenedicarbamate (containing 90.89 wt% of xylylenedicarbamate and 9.11 wt% of urethane) was placed in a static melt crystallizer , the temperature was raised to 95 °C and kept for 28 min to obtain a mixture;

[0047] (2) Cool the mixture obtained in step (1) from 95°C to 84°C at a cooling rate of 5°C / h, and after 40 min of constant temperature, use a water pump to extract the liquid in the crystallizer to obtain xylylenediamino ethyl formate crude crystal;

[0048] (3) The crude crystals of ethyl xylylenedicarbamate obtained in step (2) are heated to 102°C at a heating rate of 7°C / h, and the perspiration liquid is discharged from the outlet at the bottom of the crystallizer to obtain xylylene. pure ethyl dicarbamate;

[0049] (4) The pure ethyl xylylenedicarbamate obtained in step (3) was raised to 106°C, all the crystals in the crystallizer were melted and discharged from the bottom of the crystallizer. After weighing, 64.24 g of the product was o...

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Abstract

The invention provides a method for purifying ethyl xylylene dicarbamate by melt crystallization, which comprises the following steps: (1) heating the crude product of ethyl xylylene dicarbamate to the initial crystallization temperature to obtain a mixture; (2) Cool the mixture obtained in step (1) to the final crystallization temperature, and discharge the liquid to obtain crude crystals of ethyl xylylene dicarbamate; (3) The xylylene dicarbamate obtained in step (2) The crude crystal of ethyl dicarbamate is warmed up to the final temperature of sweating, and sweat is discharged to obtain the pure product of ethyl xylylene dicarbamate; (4) the xylylene dicarbamate obtained in step (3) The pure ethyl ester is warmed up to a molten state, and the pure ethyl xylylene dicarbamate is collected. The method for purifying ethyl xylylene dicarbamate by melt crystallization provided by the invention is energy-saving and environment-friendly, and finally obtains an ethyl xylylene dicarbamate product with a purity of more than 99%.

Description

technical field [0001] The invention belongs to the technical field of chemical separation, and relates to a purification technology of non-phosgene intermediate xylylene dicarbamate, in particular to a method for purifying xylylene dicarbamate by melting crystallization. Background technique [0002] Meta-xylylene diisocyanate (XDI) is the raw material for synthesizing polyurethane. Its products have attracted much attention in recent years because of their excellent properties such as strong abrasion resistance, high mechanical strength and low temperature resistance, as well as the non-yellowing properties of aliphatic isocyanates. . [0003] At present, the phosgene method is dominant in the method for synthesizing m-xylylene diisocyanate. However, due to the disadvantages of this method, such as high toxicity, complex process flow and unfriendly environment, more and more people are developing environmentally friendly methods. Research on non-phosgene method. The main...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C269/08C07C271/20
Inventor 贺鹏李会泉王利国徐爽曹妍郑征陈家强
Owner INST OF PROCESS ENG CHINESE ACAD OF SCI