Phase-transfer catalyzed cyanoethylation of cellulose as a reactive platform for post-functionalization into...

A novel approach based on the phase-transfer catalysis (PTC) was proposed to efficiently carry out cyanoethylation of microcrystalline cellulose (MCC) with acrylonitrile and further functionalization to form valuable derivatives. Optimization of the reaction conditions in terms of the use of polar/nonpolar aromatic solvents and different catalysts allowed determining the optimal conditions providing the best values of the degree of substitution (DS). Kinetic studies showed close-to-first-order kinetics toward the reactants (acrylonitrile and catalyst) in PTC systems while fractional kinetic behavior was observed under catalyst-free conditions, suggesting mixed kinetic-transport control. Thermodynamic analysis proved spontaneous and endothermic character of the process at elevated temperatures. Further functionalization of cyanoethylated derivative (MCC-CN) was carried out in two ways: nucleophilic addition with thiosemicarbazide (TSC) and O-(furan-2-ylmethyl)hydroxylamine (Fu-HAM), giving TSC-MCC and FOX-MCC derivatives, respectively. FTIR analysis of resulting derivatives revealed the suppression of nitrile vibration band and new bands corresponding to amides, CN, NO, and CS bonds. Solid-state ¹³C NMR evidenced removal of signals from nitrile carbon and formation of additional peaks characteristic of hydrazidine, amidoxime, and furan moieties. Finally, elemental analysis confirmed increase in nitrogen content and the presence of sulfur atoms in TSC-MCC.