Photocatalyzed Oxidation of Triphenyl Derivatives of P, As, Sb & Bi and Reduction of Their Oxides

Reaction of Triarylphosphine Radical Cations Generated from Photoinduced Electron Transfer in the Presence of Oxygen

“…This mechanism predicts a pseudo-first-order kinetics for the decay of 1 •+ under our conditions, and this is indeed the case. Alternatively, 1 •+ could undergo radical coupling with the superoxide radical anion O 2 •- generated by the electron transfer from DCA •- to O 2 (Scheme ). , However, if 1 •+ decays according to this mechanism, the decay would follow the second-order kinetics,19c which is opposite the observation. The mechanism is incompatible with the first-order kinetics even by assuming that a much higher concentration of O 2 •- than that of 1 •+ provides pseudo-first-order conditions.…”

Deoximation on irradiated TiO2: regeneration of ketones from ketoximes

“…This condition is in general favourable for photocatalytic reduction. [18][19][20] As observed in the photocatalytic reactions under an oxygen atmosphere, the photocatalytic process in the presence of nitrogen leads to the recovery of ketones from acetophenone oxime, 4-chloroacetophenone oxime, 4-bromoacetophenone oxime, benzophenone oxime and 4-chlorobenzophenone oxime (Table 1). 2-Hydroxyacetophenone oxime and 4-methoxybenzophenone oxime offer only 20% and 53% respectively of the parent ketones.…”

“…We have recently reported the use of TiO 2 as a photocatalyst in the oxidation of organic sulfur compounds, 16 aldimines 17 and Ar 3 M (M = P, As, Sb or Bi). 18 We have also successfully reduced sulfones, 19 sulfoxides, 20 nitrones 17 and Ar 3 MO (M = P, As, Sb or Bi). 18 TiO 2 has been chosen as the photocatalyst because it is chemically inert, nontoxic, biocompatible, less expensive and capable of repeated use without substantial loss of catalytic activity.…”

“…18 We have also successfully reduced sulfones, 19 sulfoxides, 20 nitrones 17 and Ar 3 MO (M = P, As, Sb or Bi). 18 TiO 2 has been chosen as the photocatalyst because it is chemically inert, nontoxic, biocompatible, less expensive and capable of repeated use without substantial loss of catalytic activity. Solutions of oximes were irradiated in the presence of suspended TiO 2 in an oxygen or nitrogen atmosphere.…”

Arylamines as More Strongly Reducing Organic Photoredox Catalysts than fac-[Ir(ppy)3]

“…In contrast, the development of strongly reducing OPCs and their application is less advanced than that of strongly oxidizing ones. ,,− Highly reducing photocatalytic systems have great potential to pave new avenues for organic syntheses based on dehalogenation, − carbanion formation from organic radicals, − and the reduction of highly oxidized stable compounds (e.g., carboxylic acids/esters, − amides, − and phosphine oxides), among other mechanisms. Meanwhile, our research group has recently developed several precious-metal complexes for the reductive transformation of various carboxylic acid derivatives − and CO 2 under thermal conditions or visible light irradiation. − Complexes of earth-abundant Fe­(II) were also used as effective CO 2 reduction sites, which were difficult to be realized without photosensitization using fac -[Ir­(ppy) 3 ] .…”