Sulfur compounds, oxidation with

Stability Unstable in air. Protect from water or moisture. Store away horn heat or ignition sources and sulfur compounds. Reacts with sulfur and sulfur compounds, producing highly toxic VX or VX-like compounds. It completely dissolves polymethylmethacrylate. It is incompatible with calcium hypochlorite (HTH), many chlorinated hydrocarbons, selenium, selenium compounds, moisture, oxidants, and carbon tetrachloride. 

Some of the patents awarded to NIAIST were in collaboration with the JCCP and some others were also shared with MITI. The first patent, issued in 2001, describes a method for oxidative removal of sulfur compounds (DBTs) with inclusion of photo and chemical catalytic processes to assist in the desulfurization [104],... 

Oxidative desulfurization of sulfur compounds Oxidation of thiophene and derivatives with hydrogen peroxide using Ti-Beta catalyst... 

The oxidative conversion of the (-)-(5 )-A-tosyl methyl-p-tolyl-sulfimide 91 to the corresponding (-)-(/ )-sulfoximide 151 is of considerable interest because the absolute configurations of the substrate and product were established by the quasi-racemate method and by X-ray analysis (98), respectively. Therefore, the stereochemical result of this experiment indicates unequivocally that oxidation of chiral tricoordinate sulfur compounds proceeds with retention of configuration. 

The O-trimethylsilyl derivative 257 of dibenzothiophene J-oxide on treatment at 78C with 2,2-dilithiobiphenyl gave the first stable tetracoordinated sulfur compound 258 with four CS bonds in 96% yield. 

The removal of sulfur compounds from fossil fuels is of great commercial and environmental importance. This process is carried out by treatment with H2 using heterogeneous catalysts (hydrodesulfurization, HDS) and generates H2S this in turn is converted to elemental sulfur by oxidation with S02 over aluminum oxide at 300°C (Claus process) 141... 

In chemical oxidation reactions, the first oxidation step (forming of sulfide radicals) is catalyzed by metal-ions like Fe, and Cu. In most sulfur compound oxidizing bacteria, the first step in the oxidation of sulfide to sulfur is catalyzed by the enzyme flavocytochrome c [3]. In a number of bacteria with the capacity to oxidize sulfide to sulfur, flavocytochrome c has not been found and other cytochromes or quinones are believed to catalyze the oxidation of sulfide in these organisms. 

Table 2.1 lists atmospheric sulfur compounds. The principal sulfur compounds in the atmosphere are H2S, CH3SCH3, CS2, OCS, and SO2. Sulfur occurs in five oxidation states in the atmosphere. (See Box) Chemical reactivity of atmospheric sulfur compounds is inversely related to their sulfur oxidation state. Reduced sulfur compounds, those with oxidation state -2 or —1, are rapidly oxidized by the hydroxyl radical and, to a lesser extent, by other species, with resulting atmospheric lifetimes of a few days. The water solubility of sulfur species increases with oxidation state reduced sulfur species occur preferentially in the gas phase, whereas the (+6) compounds often tend to be found in particles or droplets. Once converted to compounds in the S(+6) state, sulfur species residence times are determined by removal by wet and dry deposition. 

In soils and sediments rich in sulfides, abiotic reduction of Fe(III) and Mn(IV) is possible. For example, sulfides produced during sulfafe reduction can reduce Fe(III) to Fe(II) and Mn(IV) to Mn(ll). Manganese oxides are known to be more reactive with reduced sulfur compounds than with Fe(lll) oxides. 

While halides and oxyhalides of phosphorus are noncombustible liquids or solids, the sulfides are flammable. Flammability increases with an increase in the phosphorus contents of the inorganic phosphorus-sulfur compounds. Oxides are usually noncombustible. Phosphorus trioxide ignites when heated in air. 

There are three major ways of attaining sweetening (1) processes that oxidize mercaptans to disulfides, (2) processes that remove the mercaptans, and (3) processes that destroy and remove other sulfur compounds along with mercaptans, hydrogen sulfide, and sulfur. The last of these methods is usually considered as a desulfurization process. Walker and Kenney present a comprehensive discussion of the various treating processes. ... 

A major difference between alcohols and thiols concerns their oxidation We have seen earlier m this chapter that oxidation of alcohols gives compounds having carbonyl groups Analogous oxidation of thiols to compounds with C=S functions does not occur Only sulfur is oxidized not carbon and compounds containing sulfur m various oxida tion states are possible These include a series of acids classified as sulfemc sulfimc and sulfonic according to the number of oxygens attached to sulfur... 

Iron Sponge. An old method for removal of sulfur compounds involves contacting gases containing H2S and H2O with CC- or y-ferric oxide... 

Pure iron is a silvery white, relatively soft metal and is rarely used commercially. Typical properties are Hsted in Table 1. Electrolytic (99.9% pure) iron is used for magnetic cores (2) (see Magnetic materials, bulk). Native metallic iron is rarely found in nature because iron which commonly exhibits valences of +2 and +3 combines readily with oxygen and sulfur. Iron oxides are the most prevalent form of iron (see Iron compounds). Generally, these iron oxides (iron ores) are reduced to iron and melted in a blast furnace. The hot metal (pig iron) from the blast furnace is refined in steelmaking furnaces to make steel... 

Mercuric Sulfate. Mercuric s Af2iX.e.[7783-35-9] HgSO, is a colorless compound soluble ia acidic solutions, but decomposed by water to form the yellow water-iasoluble basic sulfate, HgSO 2HgO. Mercuric sulfate is prepared by reaction of a freshly prepared and washed wet filter cake of yellow mercuric oxide with sulfuric acid ia glass or glass-lined vessels. The product is used as a catalyst and with sodium chloride as an extractant of gold and silver from roasted pyrites. 

Impurities can be removed by formation of a gaseous compound, as in the fire-refining of copper (qv). Sulfur is removed from the molten metal by oxidation with air and evolution of sulfur dioxide. Oxygen is then removed by reduction with C, CO, in the form of natural gas, reformed... 

A problem associated with the use of abrasive metal poHshes is that the fresh metal, which has been exposed by the cleaning, rapidly oxidizes or tarnishes. Thus, many modem poHshes contain inhibitors. Sulfur compounds, eg, alkyl benzyl thiols, commonly are used, as are mercapto esters such as lauryl thioglycolate [3746-39-2] and dialkyldisulfides (52—54). 

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