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Sulfide Oxidation (sulfide + oxidation)
Selected AbstractsInvestigations on the Iron-Catalyzed Asymmetric Sulfide OxidationCHEMISTRY - A EUROPEAN JOURNAL, Issue 4 2005Julien Legros Dr. Abstract The development of an enantioselective sulfide oxidation involving a chiral iron catalyst and aqueous hydrogen peroxide as oxidant is described. In the presence of a simple carboxylic acid, or a carboxylate salt, the reaction affords sulfoxides with remarkable enantioselectivities (up to 96,% ee) in moderate to good yields. The influence of the structure of the additive on the reaction outcome is reported. In the sulfoxide-to-sulfone oxidation a kinetic resolution (with s=4.8) occurs, which, however, plays only a negligible role in the overall enantioselective process. Furthermore, a positive nonlinear relationship between the ee of the product and that of the catalyst has been found. On the basis of these observations, a possible catalyst structure is proposed. [source] Applications of Catalytic Asymmetric Sulfide Oxidations to the Syntheses of Biologically Active SulfoxidesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 1 2005Julien Legros Abstract Optically active sulfoxides are important compounds for medicinal and pharmaceutical chemistry. Driven by the increasing demand for efficient, selective and environmentally friendly industrial processes, several catalytic methodologies have been developed in recent years for the stereoselective oxidation of sulfides for the preparation of biologically active sulfoxides. Both small-scale approaches to the problem as well as some large-scale applications that are already in industrial use are described in this review. [source] Three enzymatic activities catalyze the oxidation of sulfide to thiosulfate in mammalian and invertebrate mitochondriaFEBS JOURNAL, Issue 13 2008Tatjana M. Hildebrandt Hydrogen sulfide is a potent toxin of aerobic respiration, but also has physiological functions as a signalling molecule and as a substrate for ATP production. A mitochondrial pathway catalyzing sulfide oxidation to thiosulfate in three consecutive reactions has been identified in rat liver as well as in the body-wall tissue of the lugworm, Arenicola marina. A membrane-bound sulfide : quinone oxidoreductase converts sulfide to persulfides and transfers the electrons to the ubiquinone pool. Subsequently, a putative sulfur dioxygenase in the mitochondrial matrix oxidizes one persulfide molecule to sulfite, consuming molecular oxygen. The final reaction is catalyzed by a sulfur transferase, which adds a second persulfide from the sulfide : quinone oxidoreductase to sulfite, resulting in the final product thiosulfate. This role in sulfide oxidation is an additional physiological function of the mitochondrial sulfur transferase, rhodanese. [source] Not so old Archaea , the antiquity of biogeochemical processes in the archaeal domain of lifeGEOBIOLOGY, Issue 5 2009CARRINE E. BLANK Since the archaeal domain of life was first recognized, it has often been assumed that Archaea are ancient, and harbor primitive traits. In fact, the names of the major archaeal lineages reflect our assumptions regarding the antiquity of their traits. Ancestral state reconstruction and relaxed molecular clock analyses using newly articulated oxygen age constraints show that although the archaeal domain itself is old, tracing back to the Archean eon, many clades and traits within the domain are not ancient or primitive. Indeed many clades and traits, particularly in the Euryarchaeota, were inferred to be Neoproterozoic or Phanerozoic in age. Both Eury- and Crenarchaeota show increasing metabolic and physiological diversity through time. Early archaeal microbial communities were likely limited to sulfur reduction and hydrogenotrophic methanogenesis, and were confined to high-temperature geothermal environments. However, after the appearance of atmospheric oxygen, nodes containing a wide variety of traits (sulfate and thiosulfate reduction, sulfur oxidation, sulfide oxidation, aerobic respiration, nitrate reduction, mesophilic methanogenesis in sedimentary environments) appear, first in environments containing terrestrial Crenarchaeota in the Meso/Neoproterozoic followed by environments containing marine Euryarchaeota in the Neoproterozoic and Phanerozoic. This provides phylogenetic evidence for increasing complexity in the biogeochemical cycling of C, N, and S through geologic time, likely as a consequence of microbial evolution and the gradual oxygenation of various compartments within the biosphere. This work has implications not only for the large-scale evolution of microbial communities and biogeochemical processes, but also for the interpretation of microbial biosignatures in the ancient rock record. [source] Distribution of ,34S and ,18O in SO2,4 in Groundwater from the Ordos Cretaceous Groundwater Basin and Geological ImplicationsACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 2 2010Yuncheng YANG Abstract: The Ordos Cretaceous Groundwater Basin, located in an arid-semiarid area in northwestern China, is a large-style groundwater basin. SO2,4 is one of the major harmful components in groundwater. Dissolved SO2,4 concentrations, and ,34S-SO2,4 and ,18O-SO2,4 in groundwater from 14 boreholes and in gypsum from aquifer were analyzed. Results show that SO2,4 in shallow groundwaters originates from precipitation, sulfide oxidation, and dissolution of stratum sulphate, with a big range of ,34S values, from ,10.7, to 9.2,, and addition of SO2,4 in deep groundwater results from dissolution of stratum sulphate, with bigger ,34S values, from 7.8, to 18.5,, compared with those in shallow groundwater. This research also indicates that three types of sulphate are present in the strata, and characterized by high ,34S values and high ,18O values-style, high ,34S values and middle ,18O values-style, middle ,34S values and low ,18O values-style, respectively. The ,34S-SO2,4 and ,18O-SO2,4 in groundwater have a good perspective for application in distinguishing different groundwater systems and determining groundwater circulation and evolution in this area. [source] Investigations on the Iron-Catalyzed Asymmetric Sulfide OxidationCHEMISTRY - A EUROPEAN JOURNAL, Issue 4 2005Julien Legros Dr. Abstract The development of an enantioselective sulfide oxidation involving a chiral iron catalyst and aqueous hydrogen peroxide as oxidant is described. In the presence of a simple carboxylic acid, or a carboxylate salt, the reaction affords sulfoxides with remarkable enantioselectivities (up to 96,% ee) in moderate to good yields. The influence of the structure of the additive on the reaction outcome is reported. In the sulfoxide-to-sulfone oxidation a kinetic resolution (with s=4.8) occurs, which, however, plays only a negligible role in the overall enantioselective process. Furthermore, a positive nonlinear relationship between the ee of the product and that of the catalyst has been found. On the basis of these observations, a possible catalyst structure is proposed. [source] | |||||||||||||