Activation of HOOH for dioxygenase chemistry

The addition of HOOH to 2 1 pyridine/acetic acid solutions that contain FeIRPA)2 (PA = picolinate ion) and cyclohexane (C-C6H12) results in the catalyzed transformation of C-C6H12 to cyclohexanone [c-CgHioCO)]. Table 4-5 summarizes the conversion efficiencies and product yields for the oxygenation by the HOOH/Fe(PA)2 combination of several organic substrates (hydrocarbons with methylenic carbons, acetylenes, and aryl olefins). Catalyst turnovers (moles of product per mole of catalyst) are also tabulated. The relative reaction efficiencies for cyclohexane, n-hexane, cyclohexene, and 1,4-cyclohexadiene are roughly 

The lower reactivity of cyclohexanol relative to cyclohexane ( l/3) indicates that c-C HjjOH is not an intermediate for the ketonization of c-C(,li 2-This is further supported by the results for a combined substrate of 1 M c-C(,lii2 and 1 M c-C HijOH, which has a ketonization efficiency of 65% (in contrast to 72% for 1 M alone. Table 4-5). Likewise, the presence of 1 M i-PrOH with 

The results establish that the pyridine/HOAc (molar ratio, 2 1) solvent system is optimal for the efficient and selective ketonization of methylenic carbons by the Fell(PA)2/HOOH system. On the basis of the relative reaction efficiencies for Fe KPA)2 and (PA)2Fe OFe H(PA)2, the initial step when Fe I(PA)2 is used as the catalyst is its transformation to (PA)2Fe OFeFI(PA)212 b, Eq. (4-38)]. The spectrophotometric, electrochemical, and magnetic results for the combination of Fe(PA)2 and HOOH in DMF confirm a 2 1 reaction stoichiometry to give a binuclear product (fc] = 2 x lO M l s ) [Eq. (4-38)]. 

Electrochemical measurements establish that (1) auto-oxidation of Fe (PA)2 in MeCN yields a product that is a mixture of 12a and 12b and (2) the product from the 1 1 combination of Felll(PA)3 and HO in DMF is mainly 12b [Eq. (4-39)]. 

The addition of species 12a to excess HOOH in DMF results in the near stoichiometric production of 102.3  

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