Selective functionalisation of saturated hydrocarbons by oxo ruthenium complexes

Abstract

Abstract Selective oxidation of saturated hydrocarbons and alcohols have been achieved by varying the type of oxidant in the oxidation reaction. The complex [Ru III (EDTA)(H 2 O)]- 1 (EDTA = ethylenediaminetetraacetato ion) catalyzes the oxidation of saturated hydrocarbons to alcohols and alcohols to the corresponding aldehydes or ketones with molecular O 2 or NaOCI as the oxidant. In both the cases, the active catalytic species is the [Ru V =O(EDTA)]- 2 ion that is characterised by elemental analysis, UV-vis, IR and cyclic voltammogram. The oxidation of saturated hydrocarbons proceed by a radical cage type of mechanism as supported by high values of k H /k D of about 12 for the reaction. [Ru III (EDTA-H)(H 2 O)] +ascorbic acid+molecular O 2 system behaves in a manner entirely different to those of Ru III -EDTA+O 2 or Ru V =O(EDTA) − . Alcohols are not oxidised by this system and it behaves in a manner similar to Barton's Gif system. A much lower value of k H /k D ∼ 3 was obtained in the oxidation of saturated hydrocarbons by this system. Dihydroxylation of cyclohexanol is preferred over its oxidation to ketone. Oxidation of adamantane gave a high value of C 2 /C 3 ∼1.3(2% 2-adamantone, 1.5% 1-adamantol).