Oxides of Sulfur, Selenium, and Tellurium

Although the molecules S20 and SO are known, they are of no real importance. The existence of similar species containing Se and Te is questionable. The only oxides of importance are the dioxides and trioxides, and consequently, only these compounds will be discussed here. 

All of the elements in Group VIA form well-defined dioxides, and Table 15.3 shows some of the properties of these compounds. 

Gaseous S02 is a toxic gas with a sharp odor. It is produced in a large number of reactions, but the usual method is burning sulfur in air  

Selenium and tellurium react in a similar way. Sulfur dioxide is also released when sulfites react with strong acids  

Selenium dioxide and tellurium dioxide are also produced by treating the elements with hot concentrated nitric acid and driving off water to leave a solid residue. Metallic tin is converted to S11O2 in a similar process (see Chapter 11). 

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Oxidation of Sulfur, Selenium and Tellurium 1 equiv. HjO, AcOH, 0 C... 

A variety of reagents will accomplish this oxidation, but the stoichiometry and temperature must be carefully controlled to avoid over-oxidation (see, for example, Uemura, S. Oxidation of Sulfur, Selenium and Tellurium. In Comprehensive Organic Synthesis , Trost, B. M., Ed. Pergamon Press Oxford, 1991 Vol. 7,758-769 and Kowalksi, P Mitka, K. Ossowska, K. Kolarska, Z. Tetrahedron, 2005, 61, 1933-1953). 

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