Ranganathan K, et al. Polymer, 2018, 135, 295-304.
2,3,4,5,6-Pentafluorobenzonitrile (PFBN) was employed as an activated perfluoroaryl substrate for the efficient construction of sulfur- and oxygen-bridged bis(2,3,5,6-tetrafluorobenzonitrile) derivatives through nucleophilic aromatic substitution (S_NAr). In dry DMF, PFBN reacted with sodium sulfide nonahydrate in the presence of potassium carbonate at room temperature for 24 h, affording 4,4'-thiobis(2,3,5,6-tetrafluorobenzonitrile) after acidic quenching, ether extraction, and chromatographic purification. The progressive dissolution of Na₂S·9H₂O during the reaction indicated in situ generation of the active nucleophile, enabling efficient C-S bond formation (49% isolated yield).
In a parallel protocol, PFBN underwent base-mediated etherification with 4,4'-(hexafluoroisopropylidene)diphenol under inert atmosphere, producing the corresponding bis(aryloxy) tetrafluorobenzonitrile in up to 80% purified yield. These experiments highlight PFBN as a versatile electrophilic building block for synthesizing highly fluorinated dinitrile monomers suitable for advanced functional materials.
