Search

In the presence of molecular oxygen or hydrogen peroxide, 1-naphthylamine (1-NA) was catalytically converted into bis(4-oxo-benzo-2-cyclohexen-1-yl) amine (BOBCHA) over metalloporphyrin catalysts through an oxidative-coupling way. UV–vis, IR, NMR, MS, mp determinations and elemental analysis were employed for product characterization. A possible catalytic mechanism based on in situ UV–vis and EPR determinations was proposed. A spectrophotometric method was established for quantitative analysis of the product according to its characteristic absorption at λ max = 465 nm. The influences of reaction conditions, such as solvents, temperature, reaction time, medium alkalinity, as well as species and amount of the catalysts were discussed in detail.

Naphthol is selectively converted into 2-hydroxy-1,4-naphthoquinone (HNQ) by relatively cheap and clean oxidant of molecular oxygen under air pressure in an alkaline solution over iron porphyrin catalysts. E.g. Fe–porphyrin (TMOPPFeCl) catalyst shows high activity (62%) and selectivity (100%) for the oxidation of naphthol to HNQ by O2 under air-pressure at 45 °C in alkaline media, where a recycle of the porphyrin catalysts is relatively simple because the product HNQ of catalytic oxidation is unsolvable in the alkaline media and separation of the porphyrin catalysts with HNQ is easily used by the filtration. Obviously, this reaction combines the advantages of high activity, high selectivity, a clean oxidant of molecular oxygen, mild conditions such as air-pressure and low temperature (45 °C), as well as recycled catalysts. Moreover, this reaction is investigated by in situ infrared spectroscopy, and a band at 881 cm−1 appears, which is possibly assigned to peroxide species. The band at 881 cm−1 completely disappears after exposure to 2-napthol, forming the reaction product HNQ. Therefore, it is proposed that peroxide species are active intermediates for the reaction.