Thioketone
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Thioketones are organic compounds related to conventional ketones. Instead of the formula R2C=O, thioketones, or thiones as they are also called, have the formula R2C=S. Unhindered thioketones are typically unstable; such compounds tend to form polymers or rings.
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[edit] Preparative methods
One approach to generating thiocarbonyl-molecules entails treating a ketone with Lawesson's reagent. Other methods use of an hydrogen chloride with hydrogen sulfide. Bis(trimethylsilyl)sulfide has also been employed.[1]
[edit] Thiobenzophenone, the prototype
Thiobenzophenone, (C6H5)2CS, is quite stable. This deep blue compound dissolves readily in organic solvents. It photooxidizes in air to benzophenone and sulfur. Since the discovery of thiobenzophenone, a variety of related thiones have been prepared by the Tokitoh group.[2]
[edit] Related compounds
[edit] Thioaldehydes
Thioaldehdyes are even more reactive than the thioketones. With sufficient steric bulk, however, stable thioaldehydes can be isolated.[3]
In early work, the existence of thioaldehydes was inferred by trapping processes. For instance the reaction of Fc2P2S4 with benzaldehyde was proposed to form thiobenzaldehyde, which forms a cycloadduct with the thiothiophophine ylides to form a C2PS3 ring.[4]
[edit] Selenones
The selenium versions of the thioketones are less stable than thiones.[2] Selenobenzophenone reversibly dimerizes. It is known to react with 1,3-dienes in a Diels-Alder reaction.[5]
[edit] References
- ^ W. M. McGregor, D. C. Sherrington (1993). "Some Recent Synthetic Routes to Thioketones and Thioaldehydes"". Chemical Society Reviews 22: 199 - 204. DOI:10.1039/CS9932200199.
- ^ a b Okazaki, R.; Tokitoh, N. "Heavy Ketones, the Heavier Element Congeners of a Ketone", Accounts of Chemical Research, 2000, volume 33, pages 625-630.
- ^ Takeda, N.; Tokitoh, N.; Okazaki, R., "Synthesis, Structure, and Reactions of the First Rotational Isomers of Stable Thiobenzaldehydes, 2,4,6-Tris[bis(trimethylsilyl)methyl]thiobenzaldehydes", Chem. Eur. J., 1997, 3, 62.
- ^ A. Capperucci, A. Degl’Innocenti, P. Scafato, P. Spagnolo (1995). "Synthetic Applications of Bis(trimethylsilyl)sulfide: Part II. Synthesis of Aromatic and Heteroaromatic o-Azido-Thioaldehydes". Chemistry Letters 24: 147. DOI:10.1246/cl.1995.147.
- ^ Erker, G.; Hock, R.; Krüger, C.; Werner, S.; Klärner, F.-G. and Artschwager-Perl, U., "Synthesis and Cycloadditions of Monomeric Selenobenzophenone", Angewandte Chemie International Edition in English, 1990, volume 29, pages 1067-68. DOI: 10.1002/anie.199010671
