Abstract: A flow-apparatus and a numerical model of diffusion with a second-order reaction in a gelatin layer were used to investigate the kinetic process of the coupling reaction of quinonedi-imines (QDI) with a water-soluble non-diffusible coupler in the gelatin layer. The results showed that the kinetic curves obtained from both experiments and the numerical model were in good agreement. It proved that the coupling reaction was a second-order reaction and the C₁₈H₃₇-substituted coupler did not form micelle in the gelation layer. This combination of experiments with the given model has been used to find the diffusion coefficient of QDI and the rate constant of the coupling reaction in the gelatin layer.

Key words: chemical kinetics, kinetics of coupling reaction, coupler