Electrophilic catalyst, silver oxide

Promoters can also influence catal5dicaUy active phases by stabilizing surface atoms in certain valence states. An example is the effect of chlorine on silver catalysts in the oxidation of ethylene to ethylene oxide. Silver oxide chloride phases were detected on the siuface. The selective epoxidation between die electrophilic oxygen and the electron-rich double bond of ethylene is optimized. Cesium promoters stabihze diese silver oxide chloride phases of the type... 

Methanol oxidation on Ag polycrystalline films interfaced with YSZ at 500°C has been in investigated by Hong et al.52 The kinetic data in open and closed circuit conditions showed significant enhancement in the rate of C02 production under cathodic polarization of the silver catalyst-electrode. Similarly to CH3OH oxidation on Pt,50 the reaction exhibits electrophilic behavior for negative potentials. However, no enhancement of HCHO production rate was observed (Figure 8.48). The rate enhancement ratio of C02 production was up to 2.1, while the faradaic efficiencies for the reaction products defined from... 

Myers oxidative decarboxylative Heck reaction became the prototype for a whole series of regiospecific oxidative couplings in which carboxylic acids adopt the reactivity of aryl electrophiles in the corresponding redox-neutral processes [67-72]. Crabtree et al. developed a process in which arenes react with aromatic carboxylates under C-H activation in the presence of a palladium catalyst and excess silver carbonate to yield biaryls. This reaction is useful especially for intramolecular couplings (Scheme 20) [73, 74]. Recently, a palladium-free, silver-catalyzed radical variant has been disclosed [78]. 

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