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Synthesis process of 4, 4'-methylene diphenyl dicarbamate

A technology of methyl dicarbamate and diphenylmethane, which is applied in the field of synthesis of MDI intermediates, can solve the problems of cumbersome process and low product yield, and achieve the goals of reducing polyreaction, simplifying operation steps, and diluting the concentration of reactants Effect

Inactive Publication Date: 2017-03-29
CHINA PETROLEUM & CHEM CORP +1
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The technical process provided by the present invention solves the problems in the prior art of using aniline, dimethyl carbonate, and formaldehyde as raw materials to prepare MDC in two steps, such as cumbersome process and low product yield, and provides an efficient and concise integrated reaction scheme

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] Add 46.50 g of aniline, 226.7 g of dimethyl carbonate, and 3.65 g of zinc acetate into the reactor in sequence, replace with nitrogen, pressurize to 0.2 Mpa, heat to 180°C, and react at this temperature for 5 h. After the reaction was completed, the temperature of the reactor was lowered to 80°C and kept at a constant temperature, and 40 mL of concentrated hydrochloric acid was added to the high-pressure reactor, and aqueous formaldehyde solution (40% mass concentration) was added dropwise using a constant flow pump at a rate of 0.15 mL / min. The time is 100 min. After the dropwise addition, the reaction was continued at 80 °C for 2 h. After the reaction was completed, the reaction solution was analyzed by high performance liquid chromatography, and the yield of methyl 4,4'-diphenylmethanedicarbamate was 67%.

Embodiment 2

[0020] Add 46.50 g of aniline, 226.7 g of dimethyl carbonate, and 3.65 g of zinc acetate into a four-neck flask in sequence, heat to 200°C, and react at this temperature for 5 h. After the reaction was completed, the temperature of the reaction solution was lowered to 80 °C and kept at a constant temperature. 40 mL of concentrated hydrochloric acid was added to the reaction bottle, and aqueous formaldehyde solution (40% mass concentration) was added dropwise using a constant flow pump at a rate of 0.15 mL / min. 100 min. After the dropwise addition, the reaction was continued at 80 °C for 2 h. After the reaction was completed, the reaction solution was analyzed by high performance liquid chromatography, and the yield of methyl 4,4'-diphenylmethanedicarbamate was 58%.

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Abstract

The invention discloses a synthesis process of 4, 4'-methylene diphenyl dicarbamate (MDC). Aniline, dimethyl carbonate and formaldehyde are adopted as the raw materials, and MPC synthesis and MDC synthesis reactions are continuous. The invention solves the defects of batch operation and complex process in the prior art employing dimethyl carbonate to prepare methylene diphenyl dicarbamate. The method includes: adding aniline, dimethyl carbonate and a zinc ion catalyst into a reactor in order to carry out reaction at 120-200DEG C for 1-10h, cooling the reaction liquid to 60-100DEG C, adding concentrated hydrochloric acid, and adding a formaldehyde aqueous solution, then carrying out reaction at 60-100DEG C for 10-200min, distilling the reaction solution to remove the solvent, and carrying out filtering, separation and recrystallization to obtain 4, 4'-methylene diphenyl dicarbamate. The overall yield is up to 67%.

Description

technical field [0001] The invention belongs to a green technology and relates to a synthesis method of an MDI intermediate. Background technique [0002] Methyl 4,4'-diphenylmethane dicarbamate (English: Methylene diphenyl dicarbamate, MDC) is an important intermediate for the clean production of diphenylmethane diisocyanate (MDI). MDC is mainly prepared by condensation of methyl phenylcarbamate (MPC) with formaldehyde or paraformaldehyde. The preparation methods of MPC mainly include aniline oxidative carbonylation method, nitrobenzene reductive carbonylation method, aniline and nitrobenzene reductive carbonylation method, urea alcoholysis method, urea method, etc. Among them, the dimethyl carbonate amination method using aniline and dimethyl carbonate as raw materials is the most environmentally friendly. This method has the advantages of mild reaction conditions, cheap raw materials and catalysts, and high product yield. Lewis acid catalyst is mainly used in the synthe...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C269/04C07C271/28
Inventor 金玉存金汉强吴其建陈永平刘卓何育苗
Owner CHINA PETROLEUM & CHEM CORP
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