Aerobic oxidation catalysis with stable radicals

Abstract

Selective oxidation reactions are challenging when carried out on an industrial scale. Many traditional methods are undesirable from an environmental or safety point of view. There is a need to develop sustainable catalytic approaches that use molecular oxygen as the terminal oxidant. This review will discuss the use of stable radicals (primarily nitroxyl radicals) in aerobic oxidation catalysis. We will discuss the important advances that have occurred in recent years, highlighting the catalytic performance, mechanistic insights and the expanding synthetic utility of these catalytic systems.

Liquid phase oxidation chemistry in continuous-flow microreactors

“…However, by the addition of a desiccant cartridge (MgSO4), activity of catalyst could be retained, and in case of 2-hexanone, the yield could be improved significantly from 75 up to 91% (Scheme 3). 5 Gavriilidis et al 144 ( Please do not adjust margins…”

“…Thus, the design of new and improved catalysts and oxidants to increase the selectivity remains a vigorous research discipline. [5][6][7][8][9][10][11] Furthermore, reaction mechanisms are often complex for oxidation processes. [12][13][14][15] The complexity is further aggravated by complex mass transport processes in e.g., multiphase oxidation processes using oxidants such as oxygen, ozone or hydrogen peroxide.…”

Aerobic Oxidations in Continuous Flow

“…The gaseous oxidant was mixed with the liquid feed and irradiated with white LEDs in a tubular sapphire photo reactor filled with glass beads to promote gas/liquid mixing. With the aid of continuous processing under high-pressure regimes, the original catalyst [Ru(bpy) 3 Cl 2 ]•6H 2 O could be replaced by the inexpensive organic dye Rose Bengal and the solvent (DMF) was substituted by a more sustainable ethanol-water mixture. Notably, a continuous reaction at 20 bar gave a quantitative reaction with a 90-fold higher productivity than the batch control experiment.…”

Synthesis, Characterization, and Relative Study on the Catalytic Activity of Zinc Oxide Nanoparticles Doped MnCO3, –MnO2, and –Mn2O3 Nanocomposites for Aerial Oxidation of Alcohols

“…In this context, noble metals such as gold [16][17][18][19][20], palladium [21], platinum [22][23][24], ruthenium [25,26], and rhodium [27,28] have been used as a heterogeneous catalyst for the alcohol oxidation with high catalytic activities and selectivities. Beside their high costs, these precious metals also have serious toxicity issues and difficulty in preparation and rarity of these noble metals makes these catalysts 2 Journal of Chemistry impractical for industrial applications [29,30]. Therefore, huge efforts have been made in order to replace these expensive noble metal catalysts with cheaper and plentiful nonnoble metals, for example, copper [31,32], cobalt [33,34], nickel [35][36][37], iron [38,39], vanadium [40], silver [41,42], chromium [43], molybdenum [44,45], rhenium [46], and zirconium [47], for selective oxidation of alcohols.…”