Mn-based oxides

Figure 2 Adsorption-desorption isotherms (N2 - 77 K) and the corresponding pore size distributions of Mn-based oxide materials...

Phenylmenthol was also used by Yang et al. in an Mn -based oxidative radical cyclization reaction catalyzed by Ln(OTf)3 (lanthanide triflate) [44]. With the achiral substrate (R = Me), the cyclization reaction was very slow in... 

G. Picasso, 2007, Preparation and characterization of Ce-Zr and Ce-Mn based oxides for n-hexane combustion Application to catalytic membrane reactors. Chemical Engineering Journal, 126,119-130. 

C02 — 12.5 mol % space velocity 6400 h 1, the CO conversion rate was found to depend very strongly on the calcination temperature of the catalyst. For example, a catalyst calcined at 500 °C achieved only 25% conversion by 350 °C, while a catalyst calcined at 900 °C achieved 80% conversion by 225 °C. The authors suggested that the Cu-Mn spinel oxide was more easily reducible after high temperature calcination treatment based on a TPR study, allowing for a greater number of highly dispersed Cu species, as verified by XRD. The optimum Cu/Mn ratio was found to be 1/2. 

Influence of other ions. Two examples are considered to illustrate the importance of other ions in natural waters on Mn(II) oxidation kinetics. In the first example the ionic composition of the solution is typical of that found in freshwaters and in the second example the composition of the solution is typical of that found in the low salinity region of an estuary (I -0.1M). The composition of these solutions is given in Davies (26). The calculated oxidation half-lives based on the model given above for these systems are shown in Table VI. 

Lovgren, L. Sjoberg, S. Schindler, P.W. (1990) Acid/base reactions and aluminium(III). Complexation at the surface of goethite. Geochim. Cosmochim. Acta 54 1301-1306 Lovley, D.R. (1992) Microbial oxidation of organic matter coupled to the reduction of Fe(III) and Mn(IV) oxides. In Skinner,... 

Alkenes and 1,3-dicarbonyl compounds together with molecular oxygen can be cyclized in a one-step synthesis to 1,2-dioxan-3-ols 159 by a thermodynamically-controlled Mn(lll)-based oxidation (Scheme 43). 

Deuterium tracer and isotope effect study of Mn(lll)-based oxidative free-radical cyclizations... 

In practice in the literature of the past 20 years the important results with ruthenium in epoxidation are those where ruthenium was demonstrated to afford epoxides with molecular oxygen as the terminal oxidant. Some examples are presented (see later). Also ruthenium complexes, because of their rich chemistry, are promising candidates for the asymmetric epoxidation of alkenes. The state of the art in the epoxidation of nonfunctionalized alkenes is namely still governed by the Jacobsen-Katsuki Mn-based system, which requires oxidants such as NaOCl and PhIO [43,44]. Most examples in ruthenium-catalysed asymmetric epoxidation known until now still require the use of expensive oxidants, such as bulky amine oxides (see later). 

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