Sulfidic sulfur, transformation

Accurate measurements of hydrogen sulfide water levels are usually complicated by the presence of other sulfide compounds. A method of determining sulfide concentration in waste water by first transforming it to hydrogen sulfide and then measuring the atomic absorption of the product yielded results ranging from 3.1 to 5.1 ppm of sulfide sulfur (Parvinen and Lajunen 1994). Total sulfide levels in samples from the Mississippi River were about 0.92 ppm, while levels in pond and well water in St. Paul, Minnesota were 1.6 and 1.9 ppm, respectively (Slooff et al. 1991). 

Figure 7. Sulfur transformations of seston-S and microbially reduced S in sediments of Little Rock Lake. This diagram is based on information collected from the lake (cores and sediment traps) and from laboratory sediment-water microcosms to which 35S was added as labeled algae or as 35S042 Sizes of circles and arrows are roughly proportional to magnitudes of pools and fluxes, respectively. ROSO3 = ester-S MeS = metal sulfide, C-S = carbon-bonded S.

Box 7. Microbial sulfur transformation in the system hydrogen sulfide - sulfate -dimethyl sulfide (after Fenchel et al, 1998)... 

Hydrogen sulfide(HiS) production and consumption quantitatively dominate microbial sulfur transformation in marine ecosystems. However, in spite of relatively high rates of sulfate reduction in marine environments, gaseous fluxes of H2S are relatively small. This emission constraining is related to ... 

Microbial sulfur transformations in the system hydrogen sulfide-sulfate-dimethyl sulfide play the most important role. Compare the role of these transformations in terrestrial and aquatic ecosystems. 

Some ores contain considerable quantities of sulfides, which transform in the environment by oxidizing processes into sulfuric acid. Other problems associated with mining operations, besides physical change, are noise, dust and high radon levels. Workers health is a serious consideration in all mining operations. 

Hydrogen sulfide is transformed into sulfur, which stays on the porous structure. Mechanisms of oxidation, the influence of water and the aulocatalysis of sulfur produced on the surface are discussed in [87], In the case of wastewater treatment plant emissions, the amount of sulfur removed by adsorption and oxidation is about 900 mg g . ... 

Roasting ofSulRdes. Most nonferrous metals occur in nature mainly as sulfides. These cannot be easily reduced directly to the metal. Burning metallic sulfides in air transforms them into oxides or sulfates which are more easily reduced. The sulfur is released as sulfur dioxide, as shown by the foHowing typical reaction for a divalent metal, M ... 

Pyridazines with an appropriate side chain attached to the sulfur atom at position 3 can be transformed into bicyclic systems. For example, pyridazinyl /3-ketoalkyl sulfides are cyclodehydrated in sulfuric acid to give thiazolopyridazinium salts, and 3-carboxymethyl-thiopyridazines are transformed by acetic anhydride in pyridine into 3-hydroxythiazolo[3,2-6]pyridazinium anhydro salts (Scheme 52). 

Sodium azide does not react with carbonyl sulfide to form 5-hydroxy-1,2,3,4-thiatriazole, nor with carboxymethyl xanthates, RO-CS SCH2COOH, to form 5-alkoxy-l,2,3,4-thiatriazoles. The latter, however, could be prepared from xanthogenhydrazides (RO-CS NHNH2) and nitrous acid. They are very unstable and may decompose explosively at room temperature only the ethoxy compound (6) has been examined in detail. This is a solid which decomposes rapidly at room temperature and even at 0°C is transformed after some months into a mixture of sulfur and triethyl isocyanurate. In ethereal solution at 20° C the decomposition takes place according to Eq. (16)... 

Contrary to the expectation that a sulfur-containing substituent will be a catalyst poison, a phenylthio group serves as an effective selectivity control element in TMM cycloadditions. A single regioisomer (30) was obtained from the carbonate precursor (31) in good yield. The thermodynamically more stable sulfide (32) is readily accessible from (30) via a 1,3-sulfide shift catalyzed by PhSSPh. A wide array of synthetically useful intermediates could be prepared from the sulfides (30) and (32) with simple transformations (Scheme 2.10) [20]. 

The oxidation of heteroatoms and, in particular, the conversion of sulfides to asymmetric sulfoxides has continued to be a highly active field in biocatalysis. In particular, the diverse biotransformations at sulfur have received the majority of attention in the area of enzyme-mediated heteroatom oxidation. This is particularly due to the versatile applicability of sulfoxides as chiral auxiliaries in a variety of transformations coupled with facile protocols for the ultimate removal [187]. 

The anaerobic degradation of halogenated alkanoic acids has, however, been much less exhaustively examined. Geobacter (Trichlorobacter) thiogenes was able to transform trichloroacetate to dichloroacetate by coupling the oxidation of acetate to CO2 with the reduction of sulfur to sulfide that carries out the dechlorination (De Wever et al. 2000). 

Interest in the possible persistence of aliphatic sulfides has arisen since they are produced in marine anaerobic sediments, and dimethylsulfide may be implicated in climate alteration (Charlson et al. 1987). Dimethylsnlfoniopropionate is produced by marine algae as an osmolyte, and has aronsed attention for several reasons. It can be the source of climatically active dimethylsulfide (Yoch 2002), so the role of specific bacteria has been considered in limiting its flux from the ocean and deflecting the prodncts of its transformation into the microbial sulfur cycle (Howard et al. 2006). 

Eastern Manus Basin Desmos cauldron (3 42 S, 151°52 E) 2000 Caldera of basalt/basaltic andesite at an intersection of a spreading center and a transform fault Sulfide ores were not recovered. Megaplume-like methane anomalies in water column over the caldera. Ferruginous oxide deposits. Pyrite and native sulfur disseminated in basaltic andesite. 

The overall transformation is the conversion of the carbon-sulfur bonds bond to a carbon-carbon double bond. The original procedure involved halogenation of a sulfide, followed by oxidation to the sulfone. Recently, the preferred method has reversed the order of the steps. After the oxidation, which is normally done with a peroxy acid, halogenation is done under basic conditions by use CBr2F2 or related polyhalomethanes for the halogen transfer step.92 This method was used, for example, to synthesize 1,8-diphenyl-1,3,5,7-octatetraene. 

Although hydrogen sulfide does not react photochemically, it may be transformed to sulfur dioxide and sulfate by nonphotochemical oxidation reactions in the atmosphere. Its atmospheric residence time is typically less than 1 day (Hill 1973), but may be as high as 42 days in winter (Bottenheim and Strausz 1980). 

Physical and Chemical Properties. Information is available on the physical and chemical properties of hydrogen sulfide (ACGIH 1991 Amoore and Hautala 1983 Budavari et al. 1996 HSDB 1998 Leonardos et al. 1969 Lide and Frederikse 1993 NIOSH 1997). However, additional information on those properties that determine the specific fate, transport, and rates of transformation of hydrogen sulfide as part of the larger sulfur cycle would be useful in discerning the environmental fate and behavior of this compound. 

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