Immobilization of manganese dioxide nanoparticles on modified poly 2,4-dichlorostyrene microspheres: a highly efficient and recyclable catalyst for borrowing hydrogen reactions

Manganese dioxide nanoparticles have been fabricated using a facile approach and immobilized onto the surface of modified poly 2,4-dichlorostyrene microspheres. The resulting multifunctional hybrid materials were characterized by scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray power diffraction and X-ray photoelectron spectrometry. This cheap heterogeneous manganese catalyst revealed excellent reactivity and stability for the direct alkylation of primary alcohols with ketones via a hydrogen borrowing pathway. In addition, this catalytic system could be readily recycled more than five times with high reactivity retained, which provided a practical atom-economical approach for C–C bond formation and 1-benzyl-2-aryl-1H-benzo[d]imidazole synthesis. Mechanism investigations were conducted to better understand this catalyst system and these transformations.