Synthesis And Catalysis Of Polymer-ruthenium Complexs

Oxidation of alcohols to the corresponding carbonyl compounds is of great importance both in academia and in industry.Ruthenium and ruthenium complexes were found to be efficient in the oxidation of secondary alcohols to the corresponding ketones with aqueous tert-butyl hydroperoxide as oxidant.The disadvantage of the ruthenium based catalysts is the difficulty of seperation of the expensive complexes from the reaction mixture,making them impossible to recycle.Heterogenization of the ruthenium complexes is expected to overcome this difficulty.First,a polymer pbbp with a 2,6-bis（benzimidazol-2-yl）pyridine tridentate ligand moiety wassynthesizedsuccessfully.Usingthispolymerasasupportand2,6-pyridinedicarboxylate as co-coordination ligand,a polymer–ruthenium complex Ru（pbbp）（pydic）was obtained.The Ru（pbbp）（pydic）was characterized thoroughly by ICP,FT-IR,UV-Vis,SEM and TGA analysis.The complex was used as a heterogeneous catalyst for the oxidation of secondary alcohols to their ketones under solvent-free conditions using TBHP as oxidant.The developed catalytic system exhibited high activity and broad functional group compatibility,allowing a variety of secondary alcohols including substituted secondary benzylic alcohols and secondary aliphatic ones,to be oxidized to the corresponding ketones in high yields.This catalyst could be recycled for several times.However,this catalyst could dissolve in part in the reaction mixture during the catalytic run,leading to gradual deactivation of the catalyst with repeated runs.The catalytic system also showed excellent performance in the oxidation of alkanes,and various alkylated arenes can be oxidized to the corresponding aryl ketones in high yields under the optimal reaction conditions.Another polymer–ruthenium complex pbbp-RuCl₃ was synthesized successfully via direction of pbbp with RuCl₃.The pbbp-RuCl₃ was characterized thoroughly by ICP,FT-IR and TGA analysis.This polymer ruthenium complex was used as a heterogeneous catalyst in the oxidation of secondary alcohols to their corresponding ketones using TBHP as oxidant.The catalytic system showed high efficiency in the oxidation of various aromatic,aliphatic and heterocyclic secondary alcohols to the corresponding kentones in high yields.This catalyst could be recycled for four times without a large reduction of its activity.The catalyst pbbp-RuCl₃ was also active in the the aerobic oxidative self coupling of primary amines to the corresponding imines.This catalytic system showed good performances in the self-coupling of aromatic and heterocyclic primary amines,but poor efficiency in oxidation of al aliphatic primary amines.