Microbially mediated oxidative

From the study of a microbially mediated oxidation of arteether 28b, sufficient quantities of 7a-hydroxy 180 and 15-hydroxy derivatives 182 were obtained to employ them as intermediates for the preparation of fluorinated compounds. The hydroxyl groups were oxidized to the corresponding aldehyde 187, or ketone 188, with catalytic quantities of tetra- -propylammonium perruthenate (TPAP) in the presence of excess iV-methylmorpholine A -oxide. On reaction with DAST, 187 and 188 were converted into the corresponding geminal difluoro derivatives, 189 (63%) and 190 (42%). In addition to 190, a monofluoro olefin 191 was obtained in 25% yield from 188 on reaction with DAST <1995JME4120>. 

The oxidation of Mn(II) by oxygen in homogeneous solution is extremely slow (on a time scale of years) (46), but it is catalyzed by the adsorption of Mn(II) on oxide surfaces (47, 48). The main oxidation pathway under natural conditions, however, is assumed to be the microbially mediated oxidation that occurs on the time scale of hours to days. The importance of microbial oxidation of Mn(II) in natural environments has been demonstrated in a number of studies (49-54). 

The microbially mediated oxidation of sulfide minerals within mine-tailings impoundments generates acidic conditions and releases high concentrations of dissolved metals. Mill tailings... 

The chemical composition of a newly formed groundwater is initially determined by rainwater (sometimes also by river water) that becomes exposed to increased partial pressure of CO2 (from the microbially mediated oxidation of organic matter in the soil horizon) after infiltration into the soil. The CO2-enriched water dissolves minerals such as aluminum silicates, CaC03, and CaMg(C03)2. 

Tebo, B.M. Fie, L.M. (1998) Microbially mediated oxidative precipitation reactions. In Sparks, D.L. Grundl, T.J. (Eds) Mineral-Water Interfacial Reactions, Washington, DC American Chemical Society, pp. 393-414. 

Murphy and Schramke (1998) first used the < 13C values to show that the increase of IICO is most likely by microbially mediated oxidation of organic carbon in lignite, not from dissolution of calcite or diffusion of CO2 from neighboring aquifers. Therefore, the total change in dissolved inorganic carbon (DIC) can be calculated from the equation... 

A major factor in the chemistry of the aquatic system shown in Figure 3.7 is the biochemical photosynthetic production of organic matter represented as CH2O. Organic matter is a biochemical reducing agent, and when it sinks into the hypolimnion it is oxidized by microorganism-mediated processes that, for example, reduce NO3 and 804 to NHJ and H2S, respectively. Two important microbially mediated oxidation-reduction reactions of CHjO are reaction with dissolved O2... 

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