Process for preparing toluene diisocyanate (TDI) by using toluenediamine and dimethyl carbonate

A technology of toluene diisocyanate and dimethyl carbonate is applied in the technical field of preparing toluene diisocyanate by using toluene diamine and dimethyl carbonate, which can solve the problem that there is no two-stage series operation decomposition reactor decomposer process introduction, no consideration The comprehensive and rational utilization of catalysts, the increase of equipment costs and production costs, etc., achieve the effects of good catalytic effect, saving operation steps and low production costs

Active Publication Date: 2014-07-23
HEBEI UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

That is, there must be a catalyst separation step, and the comprehensive and reasonable utilization of the catalyst in the process of synthesizing isocyanate is not considered
[0010] (2) For the process of carbamate decomposition to prepare isocyanate: most documents are carried out under the action of catalysts, and the catalysts used are not related to carbamate synthesis catalysts, and the decomposition temperature is high; although there are documents that do not use catalysts for decomposition reactions, However, it needs to be carried out at a very high temperature. The temperature of the first-stage reactor has reached 230-380°C, and the

Method used

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  • Process for preparing toluene diisocyanate (TDI) by using toluenediamine and dimethyl carbonate

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0044] (1) Add 5g of 2,4-toluenediamine, 97mL of dimethyl carbonate, and 0.82g of zinc acetate to reaction kettle 1 in sequence, and then seal the reaction kettle. Under stirring conditions, heat to 140°C and react for 3 hours; then raise the temperature to 170°C, and maintain the reaction for 3 hours from the start of the temperature rise, and the reaction ends. After the reaction is completed, the feed liquid is cooled and discharged, and the vacuum distillation kettle 2 is cooled at 30°C and 5kP a Under reduced pressure distillation, 10.1 g of a solid product, a mixture of methyl toluene dicarbamate and zinc oxide, was obtained. The product was analyzed by high performance liquid chromatography, and the yield of methyl toluene dicarbamate was 99.2%.

[0045] The gaseous phase that decompression distills out goes to condenser 3, obtains the liquid mixture of dimethyl carbonate, methyl alcohol and methyl acetate after condensation, separates dimethyl carbonate by conventional...

Embodiment 2

[0049] Step (1) is the same as in Example 1.

[0050] (2) Add 50mL of dibutyl phthalate to the two-stage decomposition reactors 5 and 6 respectively, and at the same time pass nitrogen, add 0.2g zinc oxide (the TDC obtained in the previous step and ZnO) to the second-stage decomposition reactor 6 mixture, ZnO was obtained after separation). Adjust the pressure of the reaction system to 10kPa, adjust the temperature of the cooling medium in the subcondenser 9 to 15°C, adjust the temperature of the cooling medium in the subcondenser 10 to 20°C, and adjust the temperature of the cooling medium in the condenser 11 to 0°C. The first-stage decomposition reaction The temperature of the reactor is 220°C, and the temperature of the second-stage decomposition reactor is 240°C. Dissolve 1.4g of the mixture of TDC and zinc oxide obtained in step (1) into an appropriate amount of dibutyl phthalate, and add it to the first-stage decomposition reactor at a uniform speed. The reaction time o...

Embodiment 3

[0052] (1) Add 5g of 2,6-toluenediamine, 104mL of dimethyl carbonate, and 0.38g of zinc acetate to reactor 1 in sequence, and then seal the reactor. Under stirring conditions, heat to 120°C and react for 1 hour; then raise the temperature to 180°C, and maintain the reaction for 2 hours from the start of the temperature rise, and the reaction ends. Cooling and discharging, the feed liquid was distilled under reduced pressure at 40°C and 15kPa to obtain a solid product of 9.71g of a mixture of methyl toluene-2,4-dicarbamate and zinc oxide, and the product was analyzed by high performance liquid chromatography. The yield of methyl toluene dicarbamate is 95.0%.

[0053] (2) Add 50mL of naphthenic oil to the two-stage decomposition reactors 5 and 6 respectively, and at the same time pass nitrogen, add 2g of zinc oxide (the mixture of TDC and ZnO obtained in the previous step, obtained after separation) into the second-stage decomposition reactor ZnO). Adjust the pressure of the r...

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Abstract

The invention relates to a process for preparing toluene diisocyanate (TDI) by using toluenediamine and dimethyl carbonate. According to the process, a deactivation catalyst, namely zinc oxide (ZnO), of a reaction, which is used for synthesizing toluene dicarbamate (TDC) through catalyzing toluenediamine and dimethyl carbonate by zinc acetate, is used as a catalyst of a reaction for TDC decomposed TDI preparation, the deactivation catalyst, namely ZnO, of the reaction is not required to be separated from the product TDC and is directly applied to the reaction for TDC decomposition catalyzed TDI preparation, and a TDC decomposed TDI preparation process adopts that decomposition reactors of two stages are in series connection and a fractional condenser is arranged between the decomposition reactors of two stages. According to the process, TDC is synthesized through catalyzing toluenediamine and dimethyl carbonate by zinc acetate, and the deactivation catalyst, namely ZnO, of TDC synthesis is selected as an efficient catalyst for TDC decomposition reaction, so that the catalysis effect is good, and the yield of TDI is high; and the temperature of the TDC decomposition reaction is low, so that the total production cost can be greatly reduced.

Description

technical field [0001] The invention uses toluene diamine and dimethyl carbonate as raw materials to synthesize methyl toluene dicarbamate, and then prepares toluene diisocyanate through catalytic decomposition. Background technique [0002] Toluene diisocyanate (TDI) is an important organic chemical intermediate and one of the important raw materials for the polyurethane industry. At present, the phosgene method is used in the industrial production of TDI, but the raw material phosgene is highly toxic, and the by-product HCl is easy to cause corrosion of equipment. Therefore, the research on the synthesis of TDI by non-phosgene method has been paid much attention at home and abroad. Among them, the process of synthesizing methyl toluene dicarbamate (TDC) by reacting toluene diamine (TDA) with dimethyl carbonate (DMC), and decomposing TDC to obtain TDI has considerable industrial potential. [0003] There have been many reports in the literature about the synthesis of carba...

Claims

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Application Information

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IPC IPC(8): C07C265/14C07C263/04
Inventor 王延吉王桂荣贾晓强赵新强
Owner HEBEI UNIV OF TECH
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