Synthesis of Polymeric Calix[4]arene Dinitrile and Diamino‐Derivatives: Exploration of Their Extraction Properties Towards Dichromate Anion

The article describes the syntheses and extraction properties of new alkylnitrile and alkylamino substituted calix[4]arene based copolymers. These compounds have been synthesized via nucleophilic substitution reactions involving 5,11,17,23‐tetra‐tert‐butyl‐25,27‐bis(cyanomethoxy)‐26,28‐dihydroxycalix[4]arene (3), or 25,27‐bis(cyanomethoxy)‐26,28‐dihydroxycalix[4]arene (4) with 1,5‐dibromopentane and bisphenol‐A, followed by their reduction with sodium borohydride in the presence of CoCl2 · 6H2O. In addition an oligomer containing pendant calix[4]arene units with nitrile functionalities on its lower rim has been synthesized via nucleophilic reaction involving 5,11,17,23‐tetra‐tert‐butyl‐25,27‐bis(cyanomethoxy)‐26,28‐dihydroxycalix[4]arene 3 with p‐dibromoxylene. The extraction properties of polymers 5–9 toward the HCr2O7 − anion are also reported. Due to the higher oxidative stability of nitrile groups, polymers 5–7 have been developed as good extractants for transferring the HCr2O7 − anion from an aqueous into a dichloromethane phase.