The Activity of Benzyl and Allyl alpha-H Sites in p-Cresol-grafted Fluorinated Poly(aryl ether oxadiazole) toward the Bromination Reaction

摘要

The energy barrier for the bromination reaction of the benzyl alpha-H and allyl alpha-H sites of p-cresol-grafted fluorinated poly(aryl ether oxadiazole) was obtained using density functional theory calculations. The simulation results indicated that the energy barrier for the bromination reaction at the benzyl alpha-H site was 80.6 kcal mol(-1), while the corresponding value for the allyl alpha-H site was 88.4 kcal mol-1, indicating that the former site was likely to be selectively brominated. This was confirmed by the bromination of p-cresol-grafted fluorinated poly(aryl ether oxadiazole) followed by (HNMR)-H-1 characterization. This result suggests that upon derivatizing benzyl alpha-H sites with a cation group (to yield an anion-exchange membrane), the allyl alpha-H sites would remain free for subsequent crosslinking. This result has positive implications for the synthesis of robust and crosslinked anion-exchange membranes based on this platform.