فهرست نشریات علمی دسترسی آزاد ایران

The kinetics and mechanism of the reaction between benzaldehyde 1, malononitrile 2 and dimedone 3 in a mixture of ethanol and water as solvents in the presence of fructose as a biodegradable catalyst has been studied by the spectroscopic method (UV-Vis spectrophotometry method). The influence of various parameters (temperature, solvent and concentration) was studied on the reaction by means of the pseudo-first order kinetic model. Based on the experimental data, the overall order of the formation reaction of tetrahydrobenzo[b]pyran  followed the second-order kinetics and under pseudo-order conditions the partial orders with respect to 1, 2 and 3 were one, one and zero, respectively. Kinetic values (k and E a ), associated with the activation parameters (Δ H ‡ , Δ S ‡ and Δ G ‡ ) of the reaction were calculated using the Eyring equation from variable temperature in kinetic studies. The initial step of the presented mechanism was determined as a rate-determining step ( k 1 ) and t was confirmed using the steady state approximation.