Heterogenisation of a C‐Scorpionate Fe^II Complex on Carbon Materials for Cyclohexane Oxidation with Hydrogen Peroxide

Abstract

Abstract The hydrotris(pyrazol‐1‐yl)methane iron(II) complex [FeCl 2 {η 3 ‐HC(pz) 3 }] (pz=pyrazol‐1‐yl) ( 1 ) was immobilized on three different carbon materials (activated carbon, carbon xerogel and multi‐walled carbon nanotubes) with three different surface treatments (original, treated with nitric acid, and treated with nitric acid followed by sodium hydroxide) to produce active, selective and recyclable catalysts. The heterogenisation process was more efficient for carbon nanotubes treated with nitric acid and sodium hydroxide. An outstanding improved catalytic performance of complex 1 upon heterogenisation on carbon nanotubes treated with nitric acid and sodium hydroxide (turnover numbers up to 5.6×10 3 and overall yield of 21 %), relative to the homogeneous system, was achieved for the single‐pot peroxidative oxidation of cyclohexane to the cyclohexanone and cyclohexanol mixture. The heterogenised systems allowed their easy recovery and reuse, at least for five consecutive cycles, maintaining 96 % of the initial activity and concomitant rather high selectivity to cyclohexanol and cyclohexanone.