Sulfur-nitrogen compounds ammonia

The chemistry of elemental sulfur and sulfur-rich molecules including polysulfides in liquid ammonia [82] and in primary as well as secondary amines [83] is complex because of the possible formation of sulfur-nitrogen compounds. Therefore, polysulfide solutions in these solvents will not be discussed here. Inert solvents which have often been used are dimethylfor-mamide (DMF) [84-86], tetrahydrofuran (THF) [87], dimethylsulfoxide (DMSO) [87], and hexamethylphosphoric triamide (HMPA) [86, 88]. 

The electrochemical reduction and oxidation of sulfur and of polysulfide dianions at inert electrodes has been studied in aprotic solvents and in liquid ammonia. In the latter case, sulfur-nitrogen compounds are involved and these systems [90] will not be discussed here. 

Potassium, sulfur (see Sulfur-Nitrogen Compounds), phosphorus (see Phosphorus-Nitrogen Compounds), coal (see Carbon Inorganic Chemistry), and dihydrogen (see Hydrogen Inorganic Chemistry) bum in an NO2 atmosphere more intensively than in an NO or N2O atmosphere. NO2 forms explosive mixtures with hydrogen mixtures with ammonia... 

A process has been developed by Haldor Tops0e that treats coal gas in the temperature range from 330° to 500°C (662°F to 932°F) and delivers a product gas that is environmentally acceptable as gas turbine fuel with regard to the common impurities sulfur, nitrogen compounds, and halogens (Nielsen and Rudbeck. 1993). The overall gas purification scheme includes halogen removal, water-gas shift conversion, ammonia adsorption, and sulfur removal. 

Although not nearly so important as the other nitrogen compounds, ammonium sulfate is still in the top 50 and is important in the fertilizer industry. Most of it is synthesized by the direct reaction of ammonia and sulfuric acid. Water is removed by evaporation and the product is crystallized to large, white uniform crystals, mp 513°C dec. 

Tellurium Halides. Tellurium forms the dihalides TeCl and TeBi, but not Tel2. However, it forms tetrahalides with all four halogens. Tellurium decafluoride [53214-07-6] and hexafluoride can also be prepared. No monohalide, Te2X2, is believed to exist. Tellurium does not form well-defined oxyhalides as do sulfur and selenium. The tellurium halides show varying tendencies to form complexes and addition compounds with nitrogen compounds such as ammonia, pyridine, simple and substituted thioureas and anilines, and ethylenediamine, as well as sulfur trioxide and the chlorides of other elements. 

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