Thioketone
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Thioketones (also known as thiones or thiocarbonyls) are organosulfur compounds related to conventional ketones. Instead of the formula R2C=O, thioketones have the formula R2C=S, which is reflected by the prefix "thio-" in the name of the functional group. Unhindered alkylthioketones typically tend to form polymers or rings.[1]
Contents
Preparative methods
Thiones are usually prepared from ketones using reagents that exchange S and O atoms. A common reagent is phosphorus pentasulfide[2] and the related reagent Lawesson's reagent. Other methods uses a mixture of hydrogen chloride combined with hydrogen sulfide. Bis(trimethylsilyl)sulfide has also been employed.[3][1]
Thiobenzophenone ((C6H5)2CS) is a stable deep blue compound that dissolves readily in organic solvents. It photooxidizes in air to benzophenone and sulfur. Since its discovery, a variety of related thiones have been prepared.[4]
Thiosulfines
Thiosulfines, also called thiocarbonyl S-sulfides, are compounds with the formula R2CSS. Although superficially appearing to be cumulenes, with the linkage R2C=S=S, they are more usefully classified as 1,3-dipoles and indeed participate in 1,3-dipolar cycloadditions. Thiosulfines are proposed to exist in equilibrium with dithiiranes, three-membered CS2 rings. Thiosulfines are often invoked as intermediates in mechanistic discussions of the chemistry of thiones. For example, thiobenzophenone decomposes upon oxidation to the 1,2,4-trithiolane (Ph2C)2S3, which arises via the cycloaddition of Ph2CSS to its parent Ph2CS.[5]
Selenones
Selenketones and tellurones the selenium and tellurium versions of the thioketones, are more reactive. They require greater steric and electronic stabilization.[1][4] Selenobenzophenone reversibly dimerizes. It is known to undergo cycloaddition with 1,3-dienes in a reaction similar to the Diels-Alder reaction.[6]
See also
- Thial, for a description of thioaldehydes.
- Thioketene
- Thioacetone
References
- ↑ 1.0 1.1 1.2 Kuhn, N.; Verani, G., "Chalcogenone C=E compounds" in Handbook of Chalcogen Chemistry: New Perspectives in Sulfur, Selenium and Tellurium, 2007, The Royal Society of Chemistry. doi:10.1039/9781847557575-00107
- ↑ Vivek Polshettiwar, M.P. Kaushik "A new, efficient and simple method for the thionation of ketones to thioketones using P4S10/Al2O3" Tetrahedron Letters 2004, Volume 45, 6255-6257. doi:10.1016/j.tetlet.2004.06.091
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- ↑ Huisgen, R.; Rapp, J., "1,3-Dipolar Cycloadditions. 98. The Chemistry of Thiocarbonyl S-Sulfides", Tetrahedron 1997, volume 53, pp. 939-960. doi:10.1016/S0040-4020(96)01068-X
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External links and further reading
- Definition of Thioketones in the IUPAC Gold Book
- Definition of Selones in the IUPAC Gold Book
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