Benzene solution, inhibited oxidation

Important information about the transformation of thiobisphenols under the conditions of inhibited oxidation were obtained on the basis of product analysis of model reactions. The detailed investigation was carried out with 4,4 -thiobis(2-methyl-6-tert-butylphenol) (CLXVIIIa), which is among the most effective thiobis-phenolic antioxidants and tert-BuOOH was chosen as a simple model of polypropylene hydroperoxide. The reaction was followed at 20 °C in benzene solution and in the presence of the catalytic amount of Co(II)acetylacetonate272). Under these conditions, the phenolic antioxidant was attacked by both alkylperoxyls and hydro-... 

Alkali metal benzhydrolate oxidizes in toluene [111] and benzene [112] as well as in f-butanol [113] with autocatalysis that is produced by the K02 formed in the oxidation [113]. The induction period disappears when K02 is added to a solution of potassium benzhydrolate. The kinetics of oxidation of sodium benzhydrolate was studied by Pereshein et al. [111]. The maximum oxidation rate appears to be approximately proportional to [RONa] [02]/[ROH],the activation energy being 12 kcal mole-1. The inhibiting action of alcohol (benzhydrol and t-butanol) on the oxidation of metal benzhydrolates was noted by Russell et al. [110], No deuterium exchange was observed during the oxidation of potassium benzhydrolate in t-butanol. Thus no dianions are produced from benzhydrolate ion by the equilibrium reaction... 

Work in this laboratory has shown also that the Ru(poip)(0)2 complexes (porp = TMP, TDCPP, and TDCPP-Clg) are practically inactive for thermal 02-oxygenation of saturated hydrocarbons . Some activity data for 0.2 mM Ru solutions in benzene under air at 25°C for optimum substrates such as adamantane and triphenylmethane at 6 mM did show selective formation of 1-adamantol and trityl alcohol, respectively, but with turnover numbers of only -0.2 per day the maximum turnover realized was -15 after 40 days for the TDCPP system Nevertheless, this was a non-radical catalytic processes there was < 10% decomposition of the Ru(TDCPP)(0)2, and a genuine O-atom transfer process was envisaged . Quite remarkably (and as mentioned briefly in Section 3.3), at the much lower concentration of 0.05 mM, Ru(TDCPP-Clg)(0)2 in neat cyclooctene gave effective oxidation. For example, at 90°C under 1 atm O2, an essentially linear oxidation rate over 55 h gave about -70% conversion of the olefin with - 80% selectivity to the epoxide however, the system was completely bleached after - 20 h and, as the activity was completely inhibited by addition of the radical inhibitor BHT, the catalysis is operating by a radical process, but in any case the conversion corresponds to a turnover of 110,000 As in related Fe(porp) systems (Section 3.3, ref. 121), the Ru(porp) species are considered to be very effective catalysts for the decomposition of hydroperoxides (eqs. 

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