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The specific features of the liquid-phase oxidation of saturated esters. Kinetics, reactivity and mechanisms of formation of destruction products

“…1) 40 and cyclohexyl acetate oxidation initiated with azobisisobutyronitrile at 333 К (Fig. 2) 42 together with the data on the composition of products of neopentyl heptano- (7), and hexanoic acid (8).…”

“…16,[35][36][37][38][39] The eff ect of the electron withdrawing group on the reactivity of the α-, β-, and γ-СН bonds of acyl and alkoxyl moieties of esters in their reactions with electrophilic peroxyl radicals can be explained by its dual (activating and deactivating) eff ect on this reaction, 16 which allows one to highlight the specifi c features of the oxidation of esters, which distinguish it from the oxidation of saturated hydrocarbons. [16][17][18] Over the past two decades, new experimental data on the reactivity of the main types of CH bonds of acyl and alkoxyl moieties of esters have been obtained, [40][41][42][43] new mechanisms of oxidation of the acyl groups involving their β-СН bonds have been established, 40,41,44 a new channel for recombination of peroxyl radicals during the ester oxidation, which occurs without the chain termination step, has been revealed. 40,41,45 Taking the liquid-phase oxidation of tert-butylphenylacetate as an example, a ki-netic model was developed.…”

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

“…At the same time, k Н for the methoxyl group is considerably higher than that for the methyl group ( Table 2). The influence of electron withdraw ing functional groups on the reactivity of the C-H bonds in the α and β positions was observed earlier for the oxidation of cyclohexanol [28], cyclohexyl ace tate [5], and butanoic acid [25]:…”

“…All of the experimental data obtained can be explained in terms of the dual effect of electron with drawing functional groups on the interaction of the C-H bonds with electrophilic peroxyl radicals [3,5,25,28]. On the one hand, the polar effect (inductive effect + field effect) of the electron withdrawing func tional group decreases the electron density on the hydrogen atom of the attacked C-H bond, thus low ering the probability of interaction with electrophilic peroxy radicals [3].…”

“…The electron withdrawing functional group affects the mechanisms of formation and transforma tion of the intermediates (peroxyl radicals and hydro peroxides) and also the reactivity of the C-H bonds nearest to this functional group [1,3,4]. It was shown for the reactions of tert butylperoxy radicals with cyclohexyl acetate at 333 K [5] that the ester group activates the α C-H bonds and substantially deacti vates the β and γ C-H bonds of the alkoxyl moiety with respect to the peroxyl radicals. 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.…”