C-H Activation Using Molecular Oxygen

Direct C-H activation of saturated hydrocarbons by heterogeneous catalysts using 02 as an oxidant under mild reaction conditions is of great importance in terms of the development of chemical processes employing abundant natural resources. For this 

1 Gates, B.C., Katzer, J.R. and Schuit, G.C. (1979) Chemistry of Catalytic Process, McGraw-Hill, New York. 

3 (a) Sheldon, R.A. and Kochi, J.K. (1994) Metal-Catalyzed Oxidations of Organic Compounds, Academic Press, New York (b) Barton, D.H.R., Martell, A.E. and Sawyer, D.T. (1993) The Activation of 

Dioxygen and Homogeneous Catalytic Oxidation, Plenum Press, New York  

4 (a) Sheldon, RA. and Kochi, J.K. (1981) Metid-Catidyzed Oxidaticns of Orgaruc Compound, Academic Press, New York  

7 (a) Hinzen, B. and Ley, S.V. (1997) Journal of the Chemical Society-Perkin Transactions 

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The recent development of inorganic crystalline-supported metal catalysts for various liquid-phase oxidation reactions such as alcohol oxidation, epoxidation, Baeyer-Villiger oxidation and oxidation via C—H activation using molecular oxygen (02) or hydrogen peroxide (H202) as an oxidant are reviewed in this chapter. 

Traditionally, these products were produced using a three-step, chlorine-based, oxidative coupling process (Fig. 1.46). In contrast, Monsanto scientists [133] developed a process involving one step, under mild conditions (< 1 h at 70°C). It uses molecular oxygen as the oxidant and activated charcoal as the catalyst (Fig. 1.46). The alkylaminomercaptobenzothiazole product is formed in essentially quantitative yield, and water is the coproduct. We note that activated charcoal contains various trace metals which may be the actual catalyst. 

Palladium-catalyzed oxidative allylic C-H functionalization provides attractive methods for the transformations of olefins, and their utility can be further enhanced by the development of more effective ways to use molecular oxygen (or air) to promote the catalytic cycle. The results outlined in this chapter summarize significant progress in the coupling reaction between terminal alkene and various types of nucleophiles. Further studies will be directed to explorations of the scope of nucleophilic reagents and olefins, and elucidation of the mechanisms of those reactions. Such studies will play an important role in the ongoing development of Pd-catalyzed C-H bond activations. 

While all these approaches point to various possible and often elegant solutions to the waste problem of the Mizoroki-Heck reaction, each still has its drawbacks. Thus, in the short term, customized solutions to minimize the waste effluent will be required for specific synthetic applications, until, in the long run, the ideal, generally applicable method is found. This could on the one hand ensue from the development of shape-selective C—H activation catalysts that by themselves are able to define the position of functionalization, to be used in the oxidative arylation of alkenes with either molecular oxygen or hydrogen peroxide... 

Zhang, G. Yu, H. Qin, G. Huang, H. Rh-Catalyzed oxidative C—H activation/annulation Converting anilines to indoles using molecular oxygen as the sole oxidant. Chem. Commun. 2014, 50,4331-1334. 

We used polycrystalline films of ZnO and Sn02 as adsorbents. The films were deposited from the water suspension of respective oxides on quartz substrates. These substrates contained initially sintered contacts made of platinum paste. The gap between contacts was of about lO" cm. All samples were initially heated in air during one hour at T 500 C. We used purified molecular oxygen an acceptor particle gas. H and Zn atoms as well as molecules of CO were used as donor particles. We monitored both the kinetics of the change of ohmic electric conductivity and the tangent of inclination angle of pre-relaxation VAC caused by adsorption of above gases and the dependence of stationary values of characteristics in question as functions of concentrations of active particles. 

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