Magnetic Field Effects on the Catalytic Oxidation of 2,6-Di-tert-butylphenol by CoSMDPT: 2H and 17O Magnetic Isotope Effects

Article abstract of DOI:10.1021/ja00219a022

The effect of a magnetic field between 0 and 70 kG on the catalytic oxidation rate of 2,6-di-tert-butylphenol, DTBP, to form 2,6-di-tert-butylquinone, BQ, by cobalt(II) bis(3-(salicylideneamino)propyl)methylamine, CoSMDPT, in the presence of O2 is reported.No kinetic 2H isotope effect is observed with DTBP-OD, and DTBP-4-d₁-OD exhibits mass and magnetic kinetic isotope effects of 1.25 and 1.22, respectively.In the presence of additive phenol, CoSMDPT catalyzes the formation of 2,2',6,6'-tetra-tert-butyldiphenoquinone, DPQ.The mass and magnetic isotope effects in DPQ formation are negligible for the deuteration of the phenolic position.DTBP-4-d₁-OD in the presence of phenol-OD exhibits kinetic mass and magnetic 2H isotope effects in DPQ formation of 1.73 and 1.31, respectively.These results are compared to the oxidation rate of DTBP by Pb(OAc)4, which is unaffected by a 0-70-kG magnetic field and has a 2H kinetic isotope effect of 1.28 for DTBP-4-d₁-OD.A significant 17O magnetic isotope effect is observed only for BQ production.The 17O enrichment of BQ given has an overall enrichment factor, S(f)=1.76, at 9percent DTBP conversion.These results are discussed in terms of a proposed mechanism.