Kinetic Studies on the Nucleophilic Aromatic Substitution of Fluoronitrobenzene Derivatives with Polyvinylamine in Water Mediated by 2,6-O-Dimethyl-β-cyclodextrin

Nucleophilic substitution of fluoronitroaromatics with polyvinylamine (PVAm) is a suitable method for producing various nitrophenyl-functionalized PVAm's. This functionalization reaction of PVAm has been studied in detail using kinetic measurements, and the degree of functionalization has been determined using model compounds as the reference system. 2-Fluoronitrobenzene (2-FNB), 4-fluoronitrobenzene (4-FNB), 1-fluoro-2,4-dinitrobenzene (Sanger's reagent), and 1,5-difluoro-2,4-dinitrobenzene (DFDNB) have been used as functionalization reagents. The solubility of the reagents in water was mediated by complexation with 2,6- O -β-dimethylcyclodextrin (β-DMCD). UV/vis spectroscopic measurements have been used to determine the degree of functionalization, rate constants, and activation energies of the nucleophilic aromatic substitution reaction. Correlation of structure and reactivity is discussed. On increasing the number of electron-withdrawing groups, the activation energies decrease. Ortho-nitro-substituted reagents require lower activation entropy than the related para-substituted reagents.