Synthesis of Silica-Supported Platinum(Ⅱ) and Nickel(Ⅱ) Complexes of Bis(Diphenylphosphinomethyl)Amino Ligand: Applications as Catalysts for the Synthesis of 2-Methyl-1,4-Naphthoquinone (Vitamin K_3)

摘要

Pt(Ⅱ) and Ni(Ⅱ) complexes of N,N-bis (diphenylphosphinomethyl)aminopropyltriethoxysilane [(CH_3 CH_2O)_3Si(CH_2)_3N(CH_2PPh_2)_2] (DIPAPTES) and silica supported [SiO_2-(DIPAPES)] ligands have been synthesized under nitrogen atmosphere using Schlenk method and characterized by using atomic absorption, FT-IR, NMR (~1H and ~(31)P) and elemental analysis techniques. All the complexes were used as catalysts for the oxidation of 2-methyl naphthalene (2MN) to 2-methyl-1,4-naphthoquinone (vitamin K_3, menadione, 2MNQ) using hydrogen peroxide as a clean and cheap oxidant. [Pt-(DIPAPTES)Cl_2] and supported complex [SiO_2-(DIPAPES)-PtCl_2] showed medium catalytic activity whereas Ni(Ⅱ) complexes did not show any catalytic activity for the selective oxidation of 2-methyl naphthalene to 2-methyl-1,4-naphthoquinone.