ABSTRACT

It is shown that tert-butyl ester 3-(3', 5'-di-tert.butyl-4'-hydroxyphenyl)- propionic acid possesses anomalously high antioxidative efficacy in radical reaction in the conditions of the initiated oxidation of iso-propyl benzene with an inhibition constant K7 = 3 × 10

6 l·mol-1·s-1 and number of stopping of chain f = 5. On the basis of results of quantum-chemical calculations enthalpies (Hfo), entropies (Sfo) and energy of a cleavage of communications OH-bond of tert.butyl and methyl ester 3-(3', 5'-di-tert. butyl-4'-hydroxyphenyl)-propionic acid are calculated energy of formation (–Ef

o). In the conditions of the initiated oxidation of iso-propyl benzene (ArH)

it is formed peroxy radical ArOO·, which participates in continuation of a chain of considerably-chain oxidation [1-3�. Specifi c reaction rates peroxy radicals with phenolic antioxidants (к7) are in limens 10

3-105 l·mol1·s-1, and values of dissociation energy О-Н depend on critical increment of energy of this reaction [3-5]. The linear relation of sizes of energy of a cleavage of communications O-Н (DOH) bond from constants к7 [6] is positioned that has allowed to use settlement procedures for forecasting of efficacy of antioxidants from their structures [7, 8�. However according to Ref. [9] reactions of some derivatives oxynaphtochinone with hydroperoxy radical are reversible also balance it is displaced towards initial components. This data will not be coordinated with the theory inhibiting oxidations on which reaction of radical RO2 with inhibitor (InOH) is reverse [3]. The analysis of the data on research inhibiting oxidation does not allow to character is unequivocally efficacy of an antioxidant on set of parameters: k7 and to number of stopping of chain (f). There was a necessity of the account of the structure factors following from geometrical and power parameters of an antioxidant.