Direct catalyst productivity

B.Zhou, andL.- K. Lee, Catalyst and process for direct catalystic production of hydrogen peroxide, (H202), US Pat. 69168775 (2001). 

A direct comparison of the productivities of the Co/nanomaterials and a typical Co catalyst23 (promoted Co/Ru-alumina catalyst) is presented in Table 2.3. Bearing in mind that the nanocatalysts are unpromoted systems and that only a simple wetness impregnation technique was employed for catalyst production, the obtained activities are quite promising, especially in the case of the Co/MW catalyst. 

Deprotection of N-2 by ozonolysis furnishes triazoles 1225 (Scheme 202) <2003JA7786>. Finding that 1,3-dipolar cycloaddition of alkynes 1222 to trimethylsilyl azide, carried out in DMF/MeOH in the presence of Cul as a catalyst, leads directly to products 1225 with much higher yields provides a significant progress to the synthesis of N-unsubstituted 1,2,3-triazoles <2004EJO3789>. 

The immobilisation of homogeneous catalysts is an intensely investigated research area in academia and industry aimed at finding novel and sustainable solutions to the most fundamental problem of the art of homogeneous catalysis the simple separation of products and catalyst and direct catalyst reuse with a minimum of additional—or even better—no further working... 

Alkenes. At present alkene isomerization is an important step in the production of detergent alkylates (Shell higher olefin process see Sections 12.3 and 13.1.3).264 265 Ethylene oligomerization in the presence of a nickel(O) catalyst yields terminal olefins with a broad distribution range. C4-C6 and C2o+ alkenes, which are not suitable for direct alkylate production, are isomerized and subsequently undergo metathesis. Isomerization is presumably carried out over a MgO catalyst. 

In this case it is a remarkable fact that experiments at different pressures and temperatures can be represented by one hyperbola. Fig. 94 immediately shows in which direction the product distribution will change when one of the process variables (the temperature, the molar ratio hydrogen wax, the life-time of the catalyst) increases. 

Olefin metathesis74 is an equilibrium reaction. It is assumed that in the first step olefin 50 adds to catalyst 56 This leads via [2+21-cycloaddition to a metallacyelobutane 57, from which ethene (58) is released and equilibrium is displaced in the direction of product Meiallacarbene 59 then reacts intramolecularly in an analogous way with the second olefin to form another metallacyelobutane ring, as shown in 60, in the decomposition of which catalyst 56 is regenerated and macrocycle 17 is released... 

In other reports, /i-cyclodcxtrins have been used to induce asymmetry in borohydride reduction of ketones,166 a diastereoselective reduction has been controlled167 by a real lyltricarbonyl iron lactone tether , a phosphinamide has been combined with a dioxaborolidine unit as an activated, directed catalyst for ketone reduction,168 reductive amination using benzylamine-cyanoborohydride converts 3-hydroxy ketones into syn-1,3-amino alcohols,169 l-(3,4-dimethoxyphenyl)-2-(2-methoxyphenoxy)propan-l-one has been reduced diastereoselectively,170 and production of chiral alcohols via (i) Itsuno-Corey and Brown procedures171 and (ii) lithium aluminium hydride modified by chiral nucleophiles172 has been reviewed. 

Major efforts in catalyst modification directed toward enhancement of catalyst productivity and the properties of the resulting polymer have resulted in a number of derivatives, which are summarized in Scheme 129 (only rac-like... 

When Tw-xylene and acetic anhydride were stirred with BEX catalyst for 4 hours at 144°, about 1% of ketone was obtained as a direct acylation product ... 

A further distinction, however, is necessary inside the field, as there are some differences among the electrogeneration of complex catalysts, and the direct electrodic production of inorganic or organic low molecular weight species acting as initiators. 

Since methanol is a direct reaction product of hydrogen and carbon monoxide, it is theoretically possible by using an excess of carbon monoxide in the original water gas mixture to form first methanol and then acetic acid or ester in one operation. With this end in view, catalysts composed of metals or their compounds, i.e. of nickel, chromium, cobalt, copper, cadmium, or manganese, have been patented.1"4 Catalysts similar to those proposed for the carbon monoxide-methanol reaction and comprising the oxides of copper, tin, lead, the acetate of copper, or tire methylates of aluminum or tin, or mixtures have been claimed for the same reaction at pressures of 150 to 200 atmospheres and at about 300° C.1 4e... 

The principal objectives of this investigation were (a) to demonstrate the feasibility of direct methane production by a single-stage multiple catalyst conversion, (b) to determine the optimum ratio of potassium carbonate to coal, holding the nickel catalyst concentration constant, (c) to determine by analytical methods and x-ray diffraction the form and amount of the potassium in the ash, and (d) to examine its water solubility. 

Two types of side reaction have been noted. The catalyst system WCVMe4Sn generates a certain amount of HCl, which adds to terminal double bonds to the extent of about 10% of the metathesis reaction (Baker 1977). The catalyst system WCl6/Et3B causes some double-bond shift in the substrate prior to metathesis with methyl undec-lO-enoate (10) a series of products of the type MeOCO (CH2)gCH=CH(CH2) COOMe are formed, the yield decreasing as n decreases from 8 (the direct metathesis product) to 7, 6, and 5 (Nakamura, R. 1976a). 

Activation can be moderate or quite substantial (up to 10-fold increase in catalyst productivity). The most likely mechanism of hydrogenolysis is the direct insertion of H2 into the metal—carbon bond (Scheme... 

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