Iron catalysis oxidation

Iron catalysis in oxidation reactions with peroxides, both hydrogen peroxide and alkyl hydroperoxides, is frequently regarded as just a Haber-Weiss-type system where hydroxyl... 

Recently, Fu and coworkers have shown that secondary alkyl halides do not react under palladium catalysis since the oxidative addition is too slow. They have demonstrated that this lack of reactivity is mainly due to steric effects. Under iron catalysis, the coupling reaction is clearly less sensitive to such steric influences since cyclic and acyclic secondary alkyl bromides were used successfully. Such a difference could be explained by the mechanism proposed by Cahiez and coworkers (Figure 2). Contrary to Pd°, which reacts with alkyl halides according to a concerted oxidative addition mechanism, the iron-catalyzed reaction could involve a two-step monoelectronic transfer. 

Oxidative addition generally increases the oxidation state of the metal by two units and, based on the common oxidation states of iron, leads from iron(0) to iron(II) or iron(-II) to iron(0). The former represents the most widespread system for iron catalysis in organic synthesis but the latter also has enormous potential for applications (see Section 1.4). 

Recently, iron catalysis gained general importance. Its catalytic chemistry has been summarized ([2] recent reviews [3, 4]). Iron(II) and iron(III) salts have a long history in radical chemistry. The former are moderately active in atom-transfer reactions as well as initiators for the Fenton reaction with hydrogen peroxide or hydroperoxides (reviews [5-12]). Important applications of this principle are the Kharasch-Sosnovsky reaction (the allylic oxidation of olefins) [13], which often... 

Metal Effects and Prooxidant Action. Ascorbic acid is prooxidant in some situations. Kanner et al. (28) showed that Cu increased the oxidation of linoleate using loss of 8-carotene as an indicator. However, when sufficient ascorbic acid was added to his system, copper catalysis was reversed. Furthermore, when Fe was added, the addition of ascorbic acid increased the prooxidant effect. Previous publications (29) have discussed the deactivation of copper catalysis by ascorbic acid, but in iron-catalyzed oxidation, Fe " initiates oxidation of lipid (2). Fe is formed from Fe by ascorbic acid. Many foods contain metals, and the... 

P.C.H. Mitchell, M. Bowker, N. Price, S. Poulston, D. James S.F. Parker (2000). Topics in Catalysis, 11/12, 223-227. Iron antimony oxide selective oxidation catalysts—an inelastic neutron scattering study. 

With this system two isomers can be formed 58 (endo) and 59 (exo). With the QUIPHOS ligand and copper catalysis, Buono and co-workers obtained very high endo/exo ratios and excellent conversion and enantioselectivity if the reagents were mixed at — 78 °C and slowly warmed to 25 °C. Imamoto and co-workers used the oxide, the 1-Ad-BisP ligand and iron catalysis at 0°C with modest results of diastereo- and enantioselectivity. Other BisP and MiniPHOS ligands led to inferior results. 

C. Wang, S. Yang, H. Chang, Y. Peng, J. Li, Structural effects of iron spinel oxides doped with Mn, Co, Ni and Zn on selective catalytic reduction of NO with NH3, Journal of Molecular Catalysis A Chemical 376 (2013) 13-21. 

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