Preparation of chitosan/poly(methacrylic acid) supported palladium nanofibers as an efficient and stable catalyst for Heck reaction

Abstract

Homogeneous chitosan/poly(methacrylic acid) solution containing Pd2+ cations was successfully prepared by addition of pyridine-2-carboxaldehyde. Then, this homogeneous solution was smoothly electrospun into uniform composite nanofibers with mean diameter of 442 ± 163 nm, followed by annealing at elevated temperature to improve the solvent resistance. Scanning electron microscopy (SEM) analysis shows that the solvent resistance of the composite nanofibers was improved with the increment of annealing temperature. FT-IR spectra demonstrate that the chemical structure of the composite nanofibers was not oxidized after annealing process. Moreover, the palladium species were homogeneously incorporated inside the composite nanofibers. The catalytic performance of these novel composite nanofibers was evaluated by Heck reaction. The catalysis result shows that these composite nanofibers were very efficient to catalyze the Heck reaction of aromatic iodides with acrylates with yields over 86%. Moreover, these composite nanofibers can be reused for 10 times with little decrement of yield. A novel palladium embedded chitosan composite nanofiber mat has been prepared by electrospinning and thermal techniques. This novel fiber palladium catalyst exhibited high catalytic activity and stability for Heck reaction.