Dithietane

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A dithietane is a four-member ring that contains two sulfur atoms and two carbon atoms. There are two main types: 1,2-dithietanes, where the two sulfur atoms are next to each other, and 1,3-dithietanes, where the sulfur atoms are separated by a carbon. The 1,2 form is rare. The first stable 1,2-dithietane discovered was dithiatopazine, made when a dithiocarbonyl compound photodimerizes with itself. 1,2-Dithietanes are different from 1,2-dithietes, which also have adjacent sulfur atoms but with sp2-hybridized carbons.

A notable 1,2-dithietane derivative is trans-3,4-diethyl-1,2-dithietane 1,1-dioxide, formed by the spontaneous dimerization of syn-propanethial-S-oxide, the onion lachrymatory agent.

In 1,3-dithietanes, the sulfur atoms are not adjacent. The parent 1,3-dithietane was first prepared in 1976 from bis(chloromethyl) sulfoxide reacting with sodium sulfide, followed by reduction of the intermediate oxide. Carbon-substituted 1,3-dithietanes have been known since 1872, including examples like 2,2,4,4-tetrachloro-1,3-dithietane, the photochemical dimer of thiophosgene, and tetrakis(trifluoromethyl)-1,3-dithietane, [(CF3)2CS]2.

Oxidized forms of 1,3-dithietane are well known, though they are often not made from the dithietane itself. Examples include the zwiebelanes (from onion volatiles) and 1,3-dithietane 1,1,3,3-tetraoxide, the sulfene dimer.