Preparation of chitosan-bound nitrobenzaldehyde metal complexes and studies on its catalytic oxidative activity and reactive mechanism

Chitosan-bound nitrobenzaldehyde metal complexes (m-CNBDM and o-CNBDM, where M is Mn or Ni) were prepared and characterized by infrared, X-ray photoelectron spectroscopy, solid-state C-13-NMR cross-polarity/magic-angle spinning, inductively coupled plasma, and elemental analysis. The complexes were found to be catalysts for the oxidation of hydrocarbons with molecular oxygen under mild conditions. o-CNBDNi has a certain catalytic activity in the oxidation of n-propylbenzene and isopropylbenzene and has no activity in the oxidation of ethylbenzene. Both o-CNBDMn and m-CNBDNi catalyze the oxidation of all the aforementioned hydrocarbons, whereas m-CNBDMn has no catalytic activity. The main oxidative products of ethylbenzene and n-propylbenzene are the same as alpha-ol and alpha-one, but they are 2-benzyl-isopropynol and isopropylbenzene peroxide for isopropylbenzene. A mechanism for the catalytic oxidative process is proposed. (C) 2002 John Wiley Sons, Inc.