Dimethyl sulfoxide/deep eutectic solvents mixtures as media in the reaction of 1-fluoro-2,4-dinitrobenzene with piperidine: A solvent effect study

Aromatic nucleophilic substitution reaction of 1-fluoro-2,4-dinitrobenzene with piperidine was kinetically investigated in ethylene glycol-choline chloride and glycerol-choline chloride as 2 deep eutectic solvents (DESs) mixed with dimethyl sulfoxide, in whole mole fractions, at room temperature. The investigation of the reaction in different concentrations of the piperidine shows that the reaction follows the base-catalyzed mechanism. The measured rate coefficients of the reaction demonstrated a sharp decreasing in all mixtures with the increasing mole fraction of DESs. Linear free energy relationship investigations confirm that hydrogen bond donor ability in addition to polarity-polarizability of the media has a major effect on the reaction rate. The decrease in the rate coefficient is attributed to not only hydrogen-bonding donor interactions of the media with piperidine as both reactant and catalyst but also the preferential solvation of reactants by DES compared with the intermediate of the reaction.