This article is about compounds with two SH functional groups. For other uses, see dithiole.
Inorganic chemistry, a dithiol is a type of organosulfur compound with two thiol (−SH) functional groups. Their properties are generally similar to those of monothiols in terms of solubility, odor, and volatility. They can be classified according to the relative location of the two thiol groups on the organic backbone.
Geminal dithiols have the formula RR'C(SH)2. They are derived from aldehydes and ketones by the action of hydrogen sulfide. Their stability contrasts with the rarity of geminal diols. Examples include methanedithiol, ethane-1,1-dithiol, and cyclohexane-1,1-dithiol. Upon heating, gem-dithiols often release hydrogen sulfide, giving the transient thioketoneorthial, which typically convert to oligomers.[1]
Compounds containing thiol groups on adjacent carbon centers are common. Ethane-1,2-dithiol reacts with aldehydes (−CH=O) and ketones (>C=O) to give 1,3-dithiolanes:
Propane-1,3-dithiol is the parent member of this series. It is employed as a reagent in organic chemistry, since it forms 1,3-dithianes upon treatment with ketones and aldehydes. When derived from aldehydes, the methyne (=CH−) group is sufficiently acidic that it can be deprotonated and the resulting anion can be C-alkylated. The process is the foundation of the umpolung phenomenon.[3]
^Cairns, T. L.; Evans, G. L.; Larchar, A. W.; McKusick, B. C. (1952). "gem-Dithiols". Journal of the American Chemical Society. 74 (16): 3982–9. doi:10.1021/ja01136a004.
^Rooney, James P.K. (2007). "The role of thiols, dithiols, nutritional factors and interacting ligands in the toxicology of mercury". Toxicology. 234 (3): 145–156. doi:10.1016/j.tox.2007.02.016. PMID17408840.
^Conrow, R. E.; Le Huérou, Y. (2004). "1,3-Propanedithiol". In L. Paquette (ed.). Encyclopedia of Reagents for Organic Synthesis. J. Wiley & Sons, New York. doi:10.1002/047084289X. hdl:10261/236866. ISBN9780471936237.