Effects of organic and inorganic initiator-catalysts on the liquid-phase oxidation of 2-isopropylnaphthalene Original Research Article

In the liquid-phase oxidation of 2-isopropylnaphthalene (2-IPN) that occurs through a free-radical chain-reaction mechanism, the initiator-catalyst of the reaction system affects the oxidation rate and product distribution. The desired product of the oxidation of 2-IPN is 2-isopropylnaphthalenehydroperoxide (2-IPNHP); however, by-products such as dimethyl-2-naphthyl-carbinol and acetonaphthone can also be produced depending on the reaction conditions. In the present study, we investigated the effects of alkaline earth metal hydroxides, i.e. Ba(OH)2, Ca(OH)2, and Mg(OH)2; an inorganic peroxide, i.e. H2O2; organic peroxides, i.e. cumenehydroperoxide and benzoyl peroxide, and the UV radiation separately on the 2-IPN oxidation rate and product distribution. In this context, the data were compared with those obtained by alkali metal hydroxides, i.e. KOH, NaOH and LiOH, and by 2-IPNHP; and further, the results were explained through the reactions that occur in the oxidation reactor. Among inorganic peroxides, organic peroxides, UV-radiation, alkaline earth metal hydroxides and alkali metal hydroxides, the oxidation of 2-IPN to 2-IPNHP favours the last two groups of initiator-catalysts where KOH and Ba(OH)2 produced 1.372 and 1.080 mol dm−3 2-IPNHP from 6.9 mol dm−3 2-IPN with 73% and 67% 2-IPNHP selectivity, respectively.