Continuous metal-free aerobic oxidations

In conclusion, NO -catalyzed aerobic alcohol oxidation is a growing research area and offers the potential for metal-free aerobic oxidation reactions. Applications of nitroxyl/NO -catalyzed oxidation reactions that employ the sterically unhindered bicyclic nitroxyls (e.g., F-AZADO, ABNO, keto-ABNO) are especially effective with a broad range of substrates bearing diverse functional groups, and reactionengineering advances that allow using these reactions in continuous processes should help to enhance reaction efficiency and promote safety. 

This chapter provides some highhghts in the innovative field of aerobic oxidation reactions in continuous flow. Topics include transition metal-catalyzed aerobic oxidations in continuous flow, photosensitized singlet oxygen oxidation in continuous flow, metal-free aerobic oxidations in continuous flow, aerobic cou-phng chemistry in continuous flow, and general prospects for scale-up. Ozonolysis is not covered in this chapter hereto, we refer to the literature [25—27]. 

Metal-Free Aerobic Oxidations in Continuous Flow... 

Regeneration of the reduced metal ion by redox reaction during catalysis is essential to continue PO degradation. Fe is the thermodynamically favored oxidation state for iron under aerobic and alkaline conditions, whereas Fe is favored under anaerobic and acidic conditions. Under most disposal and environmental conditions Mn " is favored. It is therefore unlikely that a particular metal catalyst will perform equally well in a wide range of disposal situations. Due to environmental pH values it is difficult for such catalysts to be recycled for further free radical generation. Both Fe and Fe " salts can precipitate as insoluble oxides or sulfides under environmental conditions, reducing the polymer degradation potential. 

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