Time-dependent transition from fractal to euclidean kinetics for model reaction of re-esterification

The kinetics of re-esterification model reaction of methyl benzoate by heptanol-1 was studied in the presence of nanoparticles of metals inorganic compounds. For theoretical description of the indicated reaction kinetics fractal model is used which takes into account reactionary medium heterogeneity. The kinetic curves conversion degree - reaction duration have approximately quadratic form. At small reaction times (<= 27 min) the reactionary medium heterogeneity is large that defines its low connectivity degree characterised by effective spectral dimension. At large reaction times (> 27 min) the reactionary medium becomes homogeneous (Euclidean) and its effective spectral dimension reaches two. Therefore, at the indicated reaction time, time-dependent transition from heterogeneous (fractal) kinetics to homogeneous (Euclidean) one occurs. In its turn, this change the reaction order from 2.82 up to 2.0, i.e. in homogeneous reactionary medium the re-esterification reaction proceeds as a classical reaction of second order. Such a transition is described within the framework of the Argirakis-Kopelman fractal model. It was shown also that the reaction rate constant decreases at the increase of fractal dimension of the reaction product (heptyl benzoate).