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Method for preparing isocyanate

A technology of isocyanate and methyl dicarbamate, which is applied in the field of organic compound preparation, can solve the problems of difficult separation of products and intermediates, high content of isocyanate products, and low content of crude products, and achieve easy control of heating program and simple decompression operation , high product content and high product yield

Active Publication Date: 2009-09-16
山东润兴化工科技有限公司
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The present invention aims at overcoming the shortcomings in the prior art, designing a novel process for preparing isocyanate by pyrolysis, and solving the problems in the process of preparing isocyanate by pyrolysis of aminoalkanoate through the operation method of programmed heating and programmed decompression. Poor selectivity, low yield, low product content in the crude product, difficult separation of products and intermediates, polymerization and other problems, using the control of programmed heating and programmed decompression, so that aminoalkanoates are pyrolyzed at different temperatures. At the same time, the by-product alkyl alcohol is removed from the pyrolysis system in time to realize the separation of aminoalkanoate, monoisocyanate, product isocyanate and heat carrier. The crude product obtained has a high content of isocyanate product, intermediates and heat carrier The content is very low, and effectively avoid the occurrence of polymerization reaction

Method used

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Examples

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Effect test

Embodiment 1

[0016] Put 50g of hexamethylene 1,6-methyl dicarbamate (HDU), 100g of dioctyl phthalate and 2g of zinc-zinc oxide into the reaction kettle, and replace the air in the reaction system with nitrogen , enter the program operation, raise the reaction temperature to 220°C within 1 hour, and adjust the vacuum degree of the system to -0.090MPa; keep the conditions unchanged and pyrolyze for 1 hour, start to collect the product, and raise the temperature to within half an hour 240°C, under the premise of constant temperature, gradually adjust the vacuum degree of the system to -0.098MPa until the reaction is completed; the purity of the product is 89.8% and the yield is 90.5% according to gas chromatography analysis.

Embodiment 2

[0018] Add the heat carrier and the catalyst recovered after the reaction of Example 1 into the reactor, add 5% heat carrier of the heat carrier amount, then add 50g hexamethylene 1,6-dicarbamate methyl ester (HDU), replace with nitrogen After the air in the reaction system is exhausted, enter the program operation, raise the reaction temperature to 220°C within 1 hour, and adjust the vacuum degree of the system to -0.090MPa; keep the conditions unchanged and pyrolyze for 1 hour, start to collect the product, and in half Increase the temperature to 240°C within hours, and gradually adjust the vacuum degree of the system to -0.098MPa under the premise of constant temperature until the reaction is completed; the purity of the product is 89.0% and the yield is 90.1% according to gas chromatography analysis.

Embodiment 3

[0020] Add 100g of hexamethylene 1,6-methyl dicarbamate (HDU), 200g of dioctyl phthalate and 4g of zinc-zinc oxide into the reaction kettle, and replace the air in the reaction system with nitrogen , enter the program operation, raise the reaction temperature to 220°C within 1 hour, and adjust the vacuum degree of the system to -0.090MPa; keep the conditions unchanged and pyrolyze for 1.2 hours, start to collect the product, and raise the temperature to within 1 hour 250°C, under the premise of constant temperature, gradually adjust the vacuum degree of the system to -0.098MPa until the reaction is completed; the purity of the product is 88.8% and the yield is 92.5% according to gas chromatography analysis.

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Abstract

The invention belongs to the technical field of organic compound preparation, and relates to a method for preparing isocyanate by pyrolyzing aminoalkyl esters. The method comprises the following steps: evenly mixing hexamethylene1, 6-dicarbamate, dioctylphthalate and zinc-zinc oxide into a mixture according to a mass ratio of 25:50:1; adding the mixture into a reaction kettle; replacing air in a reaction system by nitrogen, and then entering a program operation; improving a reaction temperature to 220 DEG C in 1 to 2 hours, and adjusting system vacuum degree to -0.090MPa; starting to collect isocyanate product after pyrolyzing for 1 to 1.5 hours under the condition of maintaining the temperature and the pressure; and improving the temperature to 240 to 260 DEG C in 0.5 to 1 hour, and gradually adjusting the system vacuum degree to -0.098MPa in the condition of keeping the temperature until the reaction is over. The method has reasonable process route, good selectivity, high product yield, and high content, and is easy to be separated and polymerized with a midbody, simple in decompression operation and suitable for industrial production.

Description

Technical field: [0001] The invention belongs to the manufacturing process and operation process in the technical field of organic compound preparation, and relates to a method for preparing isocyanate by pyrolyzing aminoalkanoate. Background technique: [0002] Isocyanate is an important class of organic compounds, widely used in polyurethane industry, paint industry, dyes and pesticides, etc., and polyurethane is one of the six most promising synthetic materials in the world. Commonly used isocyanates are toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI), polymethylene polyphenyl polyisocyanate (PAPI) and hexamethylene diisocyanate (HDI). At present, the production of isocyanate compounds at home and abroad mainly adopts the phosgene method. Due to the harsh reaction conditions and complicated process of the phosgene method, and the use of highly toxic raw material phosgene, a large amount of highly corrosive hydrochloric acid ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C263/04C07C265/14
Inventor 张永富冯柏成管宪文王莉丁玉赵战如潘月
Owner 山东润兴化工科技有限公司
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