The Study Of The Reaction Of Biological Enzyme Catalyzing And Synthesizing Toluene Diisocyanate

Toluene Diisocyanate ( TDI), an important organic medium, is mainly applied in the making of poly urethane(PU). The method that Toluene Dicarbamate(TDC)is synthesized by Dimethyl Carbonate (DMC) instead of phosgene, and then is decomposed and forms TDI is a green and healthy way.Biological enzyme is characterized by a strong catalytic activity in the organic solvent, and it has many advantages, such as mild reaction requirement, easy aftertreatment, stable structure, and retaining activity, etc. therefore, I chose biological enzyme as the catalyzer, and by means of mathematical analysis, I studied the function of enzyme in the synthetic process TDC by DMC and TDA.After making selection to 11 enzymes, papin, flavourzyme, pepsin, and eaterase from porcine liver are proved to have catalytic activity to the reaction, and I found out the catalyzer that has fairly strong catalytic activity and selectivity- papain. What's more, I sorted out the most suitable solvent- Tetrahydrofuran, with 15ml/g papain. And an optimization to the reaction is made, when the temperature is 40 °C, n(TDA)/n(DMC)=l/20, and the enzyme concentration is 17.4mg/m, the TDC yield can reach 3.94% after reacting for 40 minutes.With the response surface methodology, I studied the influence of the interaction of three factors to the rate of production of TDC. The three factors are: enzyme concentration (3.5-31.3 mg/ml) , the volume of DMC (6.9-20.7 ml) and the temperature for reaction (25~55℃) . Through further analysis to the equation, it is learned that the rate of production of TDC has a great value 4.02% within chosen limits.I made a study to the multiple factors that will affect the activity of Papin. Papin has the best catalytic activity under the following conditions: enzyme concentration is 1 mg/ml, value of PH 7.0, temperature of reaction 40℃, the concentration of the activator CYS HC1 0.04mol/l, time for reaction 30 minutes, and time for keeping temperature 30 minutes. After the experiment, it is found that the organic solvent Tetrahydrofimuu DMC can influence the enzyme activity of Papin to a certain degree. When the concentration of Tetrahydrofuran is 60% (V/V) , the enzyme activity can reach its highest value 12.84 X 105U/mg; when the concentration of DMC is 40% (V/V) , the enzyme activity can reach its highest value 9.76 X 105U/mg.