Kinetics of the acid-catalyzed cardanol–formaldehyde reactions

A kinetic study of the reaction of cardanol (C) and formaldehyde (F) (molar ratio 1:0.5) was carried out at four different temperatures ranging between 100 and 130 °C with an interval of 10 °C using three different catalyst systems. The reaction between cardanol and formaldehyde was found to follow second-order rate kinetics with all three catalyst systems. The change of the catalyst system affected the values of k, k1, and k2 with temperature. In all the systems, the values of k1 were found to be lower than the values of k2. Based on the values of rate constants, various other parameters such as activation energy (Ea), change in enthalpy (ΔH) and entropy (ΔS), and free energy change (ΔG) of the reaction were also evaluated. It was found that the condensation reaction of cardanol and formaldehyde with di- and tricarboxylic acids was anti-spontaneous and irreversible.