Hydrogen peroxide formation in the oxidation of carbonyl-containing compounds at ?-CH bonds

Reactivity of the C-H bonds of methyl hexanoate toward the tert-butylperoxy radical

“…The value w i,CP = 1.78 × 10 -8 mol L -1 s -1 was obtained by determining the rate of inhibitor (ionol) consumption in the CP initiated oxidation of methyl hexanoate (373 K, [RH] = 6.46 mol/L, [CP] = 0.006 mol/L). This value agrees well with w i,CP = 1.77 × 10 -8 mol L -1 s -1 value, which was calculated using the following relationship [23]: (6) where the factor 144.3 has dimensions of kJ/mol. At 373 K and е = 0.6, k i,CP = 2.94 × 10 -6 s -1 [23].…”

“…It has recently been demonstrated that the oxida tion of carbonyl containing compounds (including esters) at the β C-H bonds yields α,β unsaturated compounds [6][7][8]25] and their oxides [7,25]. The oxidation of methyl hexanoate via these mechanisms should result in the formation of methyl 2 hexenoate and methyl 2,3 epoxyhexanoate (routes а and b in the scheme presented below).…”

“…The oxidation of methyl hexanoate via these mechanisms should result in the formation of methyl 2 hexenoate and methyl 2,3 epoxyhexanoate (routes а and b in the scheme presented below). The observation of the pre cursor of these compounds, namely, carbon centered radical А [6][7][8]25] suggests the possibility of its trans formation (via interaction with oxygen and the sub strate) into methyl 2,3 dihydroperoxyhexanoate. The reduction of the latter gives methyl 2,3 dihydroxyhex anoate (route c): …”

“…Although there have been many works devoted to ester oxidations (see monograph [1] and review [3]), the influence of the functional group on the reactivity of various types of C-H bonds in the acyl moiety remains unclear. The discovery of a new mechanism and new products of the oxidation of carbonyl containing compounds at the β C-H bonds [6][7][8] makes disputable the results of an earlier study [9] in which the relative reactivity of the C-H bonds of methyl hexanoate were determined from the composition of the alcohols that resulted from the reduction of the oxidation products of this ester with lithium aluminum hydride at 413 K.…”

Contribution from two types of peroxyl radicals to cyclohexanol oxidation and their reactivity

“…Nitrobenzene is an inhibitor that selectively inter acts with hydroperoxyl radicals [9][10][11]. As a conse quence, in alcohol oxidation in the presence of nitrobenzene, the concentration of hydroperoxyl rad icals decreases substantially due to linear law chain termination and oxidation is mainly ensured by α hydroxyperoxyl radicals.…”