<p>In developing effective catalytic systems, understanding the interaction between reactant(s) and organocatalysts plays a crucial role in establishing the structure–activity relationship (SAR) in catalysis. This work investigated the interaction between imidazole, an organocatalyst, with the reactants in the Knoevenagel condensation of 2-chlorobenzaldehyde with malononitrile and ethyl cyanoacetate. Due to the solvent's impact on plausible interactions between reactants, organocatalysts, and intermediates, the study was conducted using FTIR and 1D NMR spectroscopic techniques. There was a correlation between the reduction of the acid methylene group intensity in ¹³C NMR spectra and the activity of acid methylene compounds. A reduction in α-carbon intensity of 75% and 23% for the malononitrile and ethyl cyanoacetate, respectively, was observed in the presence of one equivalent of imidazole. Moreover, the study introduced a greener and more sustainable solid-state procedure for the gram-scale preparation of 2-chlorobenzylidene malononitrile and 2-chlorobenzylidene cyanoacetic acid ethyl ester using a catalytic loading of imidazole, demonstrating the economic and practical aspects of the slurry mechanochemical process. The crystalline pure products could be isolated directly from an ethanol solution, and the residue containing imidazole was used in the next reactions without purification or activation after removing ethanol with a rotary evaporator.</p> Graphical abstract <p></p>