SUBJECTS compounds 718, oxide

When an aromatic compound having an aliphatic side chain is subjected to oxidation, fission of the side chain occurs between the first and second carbon atoms from the benzene ring, the first carbon atom thus becoming part of a carboxyl ( -COOH) group. For example ... 

Whereas the addition of early metal soaps to a coating for the specific purpose of improving the drying performance did so, the compounds lacked uniformity of composition and therefore did not give predictable results. Even if all of the metal reacted with the acid to give an expected metal ion concentration, which seldom happened, the ions were subject to oxidation, which resulted in loss of solubiUty in the vehicle and therefore a loss of activity. 

The reactions of olefins with peracids to form epoxides allows for the selective oxidation of carbon-carbon double bonds in the presence of other functional groups which may be subject to oxidation (for example, hydroxyl groups). The epoxides that result are easily cleaved by strong acids to diols or half-esters of diols and are therefore useful intermediates in the synthesis of polyfunctional compounds. 

Phenol, the simplest and industrially more important phenolic compound, is a multifunctional monomer when considered as a substrate for oxidative polymerizations, and hence conventional polymerization catalysts afford insoluble macromolecular products with non-controlled structure. Phenol was subjected to oxidative polymerization using HRP or soybean peroxidase (SBP) as catalyst in an aqueous-dioxane mixture, yielding a polymer consisting of phenylene and oxyphenylene units (Scheme 19). The polymer showed low solubility it was partly soluble in DMF and dimethyl sulfoxide (DMSO) and insoluble in other common organic solvents. 

Cells may show a low level of autofluorescence at 413 nm when irradiated at 324 nm. This fluorescence dramatically increases when d -parinaric acid (159) is incorporated into the cell membrane, either by intercalation or esteriflcation. Exposure to oxidation stress of cells enriched with the 159 fluorescent probe causes diminution of the fluorescence intensity and is directly correlated with formation of lipid hydroperoxides. Addition of antioxidants, such as Vitamin E (21), abates fluorescence diminution. A blanc run of cells enriched with 159 but not subjected to oxidation stress is necessary to follow the degradation of 159 when exposed to UV irradiation. This method was applied to track lipid oxidation during apoptosis and other phenomena, triggered by toxic compounds such as H2O2, f-BuOOH and cumyl hydroperoxide (27)"° 11,424... 

An alternative method to TBARS for determination of MDA is formation of the DNP derivative and quantitation by RP-HPLC with DA-UVD, recording in the 195 to 500 nm range. Other carbonyl compounds present in the sample also form the corresponding DNP compounds and are also determined. The method was applied to MDA determination in plasma of rats, after they were subjected to oxidative stress by intraparental injection of a dose of bacterial lipopolysaccharide" . 

Fabios, M. et ak. Phenolic compounds and browning in sherry wines subjected to oxidative and biological aging, J. Agric. Food Chem., 48, 2155, 2000. 

The 2//-chromene part of the naturally occurring lonchocarpin (206) remains unaltered when the compound is subjected to oxidation. This helped to determine the structure of lonchocarpin (53MI22300). 

Exhaust emission standards since the 1981 model year vehicles have required the use of three-way catalysts, either alone or in combination with an oxidation catalyst. Three-way catalysts are designed to operate in a very narrow range about the stoichiometric air/fuel ratio. In this range the HC and CO are subject to oxidation and the NO, compounds undergo reduction. The downstream oxidation catalyst in a dual bed system is generally used as a "clean-up catalyst lo further control HC and CO emissions. The most common catalytic combination in three-way uses is platinum/rhodium. Current production applications use these elements in a relatively rich proportion of 5 1 lo 10 1. whereas the respective mine ratio is about 19 1. 

There are quite a number of routes available for the production of iridium(ni) alkyl compounds. In addition to the halide displacement and olefin insertion pathways noted above for iridium(l) compounds, oxidative addition of C-H bonds to iridium(l) to form iridium(in) hydrido alkyl complexes is also a possibihty. This subject will be covered in detail in Section 9 and will not be discussed here. However, there are other oxidative addition routes that lead to the formation of iridium(lll) alkyls. First, oxidative addition of O2 or HCl to some alkyl and aryl iridium(l) complexes can produce iridium(lll) alkyl or aryl compounds. In some cases, HgCl2 can add, but this appears to lead to tractable products only for the very stable pentafluorophenyl complex. Of course, oxidative addition see Oxidative Addition) of alkyl halides such as H3CI will also yield alkyl iridium(lll) compounds. Addition of Mel to Vaska s compound yields a stable iridium(III) complex, but addition of Etl does not produce a stable compound, presumably due to subsequent /J-hydride elimination see fi-Hydride Elimination). A number of mechanistic studies have been done on the oxidative addition of alkyl halides to iridium(l), especially Vaska s complex see Vaska s Complex). 

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