Kinetics of the reactions of 4 4'- methylene diphenyl diisocyanate with different alcohols

This experiment was performed at the department of applied chemistry, I reacted 4,4′-diphenylmethane-diisocyanate with 1-hexanol and 2-hexanol (separately) at different temperatures (50ºC–80ºC), after the given time intervals, 20μL of samples were taken from the reaction mixture and quenched in 980μL methanol. The HPLC measurements of the quenched samples were then taken. From the HPLC spectrums results I was able to plot the graph of the measured values and calculated values of the products of the reactions against the reaction time. This plot was then used to determine the rate of the reactions k1 and k2 of each of the measurements. The results of the rate of the reactions showed that primary alcohols have a faster rate of reaction than secondary alcohols and the k1 values are higher than k2 values in the reactions. I calculated the ratio k1/k2 which was between 1.5–1.7. Also, it showed that the rate of reaction increases with an increase in temperature. I used the logarithmic Arrhenius equation to calculate the activation energy, I plotted ln k1 and k2 values(separately) against 1/T for each alcohol to find the slope. I got approximately 28 kJ/mol for 1-hexanol and approximately 40 kJ/mol for 2-hexanol. The results are in good agreements with the determined reaction rate constants. In the case of 1-hexanol the rate of reaction is greater and its activation energy is lower than that of 2-hexanol.BSc/BAchemical engineeringLBg