| Abstract: | The extent of reaction between a liquid polyfunctional aromatic isocyanate and a diol was studied using infrared spectroscopy to follow the reduction in concentration of the isocyanate group. For the homogeneous conditions the reaction was performed in benzene solution. For the heterogeneous conditions the isocyanate was dispersed as droplets in the diol and the reaction proceeded interfacially. From a proposed model for the interfacial reaction based on the steady-state diffusion theory the second-order rate constant of the reaction can be evaluated. The values obtained were compared to the second-order rate constants obtained for the solution method. For a range of temperature the heterogeneous rate constant was approximately six decades higher than that obtained for the homogenous conditions. However the activation energies obtained corresponded within a factor of 1.5. |
