Use of an Organometallic Palladium Oxazoline Catalyst for the Hydrolysis of Methylparathion
摘要:
Reaction of (S)-4-carbomethoxy-2-phenyl-2-oxazoline with Pd(OAc)2 leads to the formation of the ortho-palladated complex (SS)-di-mu-(acetate)-bis{2-[2-(4-carbomethoxy)oxazolinyl]-phenyl-C,N}dipalladium(II) (1). In the presence of water, this complex reacts with methylparathion to produce p-nitrophenol as well as two oxazoline palladium dimethylthiophosphate complexes (2 and 3), which have been observed in solution by P-31 NMR. This reaction is accompanied by racemization of the oxazoline ligand and ultimately produces the dinuclear complex (R,S)-di-mu-(dimethylthiophosphate-SS)-bis{2-[2-(4-carbomethoxy)oxazolinyl]phenyl-C,N}dipal-ladium(II) (4), which features bridging dimethylthiophosphate ligands. At pH 9-10, complex 1 serves as a precatalyst for the hydrolysis of methylparathion. The reaction rate has a first-order dependence in substrate and palladium catalyst with a second-order rate constant of 726 (+/- 30) M-1 s(-1) at pH 9.0.