Oxidation screening conditions

Watei has an unusually high (374°C) ctitical tempeiatuie owing to its polarity. At supercritical conditions water can dissolve gases such as O2 and nonpolar organic compounds as well as salts. This phenomenon is of interest for oxidation of toxic wastewater (see Waste treatments, hazardous waste). Many of the other more commonly used supercritical fluids are Hsted in Table 1, which is useful as an initial screening for a potential supercritical solvent. The ultimate choice for a specific appHcation, however, is likely to depend on additional factors such as safety, flammabiUty, phase behavior, solubiUty, and expense. 

At an industrial scale, the esterification catalyst must fulfill several conditions that may not seem so important at lab-scale. This must be very active and selective as by-products are likely to render the process uneconomical, water-tolerant and stable at relatively high temperatures. In addition, it should be an inexpensive material that is readily available on an industrial scale. In a previous study we investigated metal oxides with strong Bronsted acid sites and high thermal stability. Based on the literature reviews and our previous experimental screening, we focus here on application of metal oxide catalysts based on Zr, Ti, and Sn. 

Screening is usually carried out with liver microsomes from humans, rats, mice, dogs and monkeys and liver S9 fraction from aroclor 1254-induced rats. The incubation is typically mn with a volume of 0.2-1. OmL in a microcentrifuge or a glass tube. Different incubation conditions are used for CYP and UGT reactions. The incubation mixture for formation of oxidative metabolites and/or GSH conjugates contains ... 

The first of the three steps used to find new catalysts was to screen the entire pooled collection of complexes for compatible reaction conditions. This process identified aqueous H202 as an effective oxidant. The second stage of the process was to screen the active metal libraries for epoxidation of frans-P-methylstyrene (TBMS). Activity was determined on a mixture of all 192 ligands, with each indi-... 

As discussed above, the level of sensitivity of most gas-phase oxidation catalysts is high with regard to the reaction temperature. Therefore, any Stage II-screening tool should operate under isothermal conditions for all active materials, and it is a given prerequisite that thermal equilibrium of the reactor and a homogeneous temperature distribution are essential. 

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