Oxygen sulfide oxidation

The dissolved hydrogen sulfide is oxidized to form a mixture of elemental sulfur and hydro-quinone. The solution is injected with air or oxygen to oxidize the hydro-quinone back to quinone. The solution is then filtered or centrifuged to remove the sulfur and the quinone is then reused. 

A mixed sulfide-oxide, P4OgS4, has a structure similar to that of P4O10, except sulfur atoms replace the four oxygen atoms in terminal positions. 

Aryl and alkyl hydroxylations, epoxide formation, oxidative dealkylation of heteroatoms, reduction, dehalogenation, desulfuration, deamination, aryl N-oxygenation, oxidation of sulfur Oxidation of nucleophilic nitrogen and sulfur, oxidative desulfurization Oxidation of aromatic hydrocarbons, phenols, amines, and sulfides oxidative dealkylation, reduction of N-oxides Alcohol oxidation reduction of ketones Oxidative deamination... 

Oxygen becomes oxide Nitrogen becomes nitride Fluorine becomes fluoride Chlorine becomes chloride Sulfur becomes sulfide Carbon becomes carbide... 

Vazquez R, Vennemann TW, Kesler SE, Russell N (1998) Carbon and oxygen isotope halos in the host hmestone, El Mochito Zn, Pb (Ag) skam massive sulfide/oxide deposit, Honduras. Econ Geol 93 15-31... 

Table 9.1 Oxidation of sulfides ArSR to sulfones catalyzed by LDH-OSO4 using molecular oxygen as oxidant.

Yarlett N, Orpin CG, Munn EA, Yarlett NC, Greenwood CA (1986) Hydrogenosomes in the rumen fungus Neocallimastix patriciarum. Biochem J 236 729-739 Yong R, Searcy DG (2001) Sulfide oxidation coupled to ATP synthesis in chicken liver mitochondria. Comp Biochem Physiol 129 129-137 Zebe E (1991) Arthropods. In Bryant C (ed) Metazoan Life Without Oxygen. Chapman and Hall, London, pp 218-237... 

As this short discussion shows, the kinetics of formation of the single parameters (Fe2+ and H2S) may control the extent and the pathway of pyrite formation. Oxidation of sulfide by elemental sulfur to form poly sulfides (pathway 1) should predominate at the oxygen-sulfide interface of very productive... 

Figure 6. An idealized scheme for a sedimentary porous medium with pore walls covered by a biofilm. High sulfate reduction rates are maintained even in depths to which sulfate cannot diffuse because of recycling of sulfate within the biofilm. Numbered points (in black circles) denote the following processes I, Respiration consumes oxygen. 2, Microbial reduction of reactive metal Oxides. Reduction of reactive ferric oxides is in equilibrium with reoxidation of ferrous iron by Os. Thus, no net loss of reactive iron takes place in these layers. 3, Microbial reduction of ferric oxides. 4, Sulfate reduction rate (denoted as SRR). 5, Sulfide oxidation, either microbiologically or chemically. 6, Sulfide builds up within the hiofilm, sulfate consumption increases, reactive iron pool decreases. 7, Formation of iron sulfides.

Mention has already been made of the uciion of oxygen and oxidants on metal. It should be noted that metals react with sulfides, such as hydrogen sulfide, and are subsequently subject to additional slow attack by oxygen and oxidants. Thus, copper reacts to form sulfide and then the basic copper sulfate. 

Pseudomonas oleovorans contains P. oleovorans monooxygenase (POM), which is a typical co-hydroxylase for hydroxylation of the terminal methyl of alkanes as well as epoxidation of terminal olefins. The co-hydroxylation system of P. oleovorans was reconstituted from purified components, POM, rubredoxin, and a flavoprotein reductase [122], In the presence of NADH and oxygen, it oxidizes a wide range of aliphatic methyl alkyl sulfides. Enantioselectivities are very much dependent of the length of the alkyl chain of Me-S(0)-R, as exemplified by the following results ... 

Pasta P, Carrea G, Monzani E, Gaggero N, Colonna S (1999) Chloroperoxidase-Catalyzed Enantioselective Oxidation of Methyl Phenyl Sulfide with Dihydroxyfumaric Acid/Oxygen or Ascorbic Acid/Oxygen as Oxidants. Biotechnol Bioeng 62 489... 

The first example of iron-catalyzed asymmetric oxidation of sulfides was described by Fontecave and coworkers in 1997 [163]. An oxo-bridged diiron complex, which contained (—)-4,5-pinenebipyridine as chiral ligand, was reported to catalyze sulfide oxidations with H202 in acetonitrile, having the potential to transfer an oxygen atom directly to the substrates. However, the enantioselectivity of this process remained rather low (<40% ee, Scheme 3.53). 

In reality, the oxidation of pyrite and other Fe(II) sulfides typically involves several intermediate reactions, which may be enhanced by microbial activity or various chemical species, such as bicarbonate (HCO3-) (Welch et al., 2000 Evangelou, Seta and Holt, 1998). The exact mechanisms of each intermediate reaction are often very complex and poorly understood (Rimstidt and Vaughan, 2003). Mostly likely, sulfide oxidizes in pyrite before iron. Fe(II) is then released into solution as shown by the following reaction involving oxygen and water (Gleisner and Herbert, 2002, 139-140) ... 

Based on the results of Powell and Somero C22.25.48 > there was reason to believe that much of this sulfide oxidizing activity was localized in the mitochondria of the animals. The addition of radiolabeled sulfide to isolated mitochondria has allowed us to show for the first time that the oxidation of sulfide by Solemya mitochondria is an organized biochemical process and not a non-specific oxidation caused by heme groups or other metal ions. As shown in Figure 5, the oxidation of radioactive sulfide in healthy mitochondria results in a stimulation, not an inhibition, of oxygen consumption and the production of thiosulfate as a final oxidation product. This corresponds to the appearance of thiosulfate in the blood. This activity was not present in rat mitochondria and... 

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