{{Short description|Class of chemical compounds}} thumb|right|250px|Structure of a 1,3-dithietane (left) and 1,2-dithietane (right), where R is an organic group A '''dithietane''' is a saturated heterocyclic compound that contain two divalent sulfur atoms and two sp<sup>3</sup>-hybridized carbon atoms.<ref>{{cite journal |last=Drabowicz |first=J |author2=Lewkowski, J |author3=Kudelska, W |author4= Zając, A | title =Four-membered Rings with Two Sulfur Atoms |journal =Comprehensive Heterocyclic Chemistry III |year=2008 |volume=2 |issue=18 |pages=811–852 |doi=10.1016/B978-008044992-0.00218-2}}</ref><ref>{{cite encyclopedia|entry=Four-membered rings with two sulfur atoms|first=Uri|last=Zoller|encyclopedia=Comprehensive Heterocyclic Chemistry|edition=IInd (covering 1982-1995)|volume=1B (Four-membered Rings)|editor-first=Albert|editor-last=Padwa|publisher=Pergamon|year=1996 |issue=35 |pages=1113–1138 |doi=10.1016/B978-008096518-5.00035-6|isbn=9780080965185 }}</ref> Two isomers are possible for this class of organosulfur compounds:

== 1,2-Dithietanes == 1,2-dithietanes, 4-membered rings where the two sulfur atoms are adjacent, are very rare. The first stable 1,2-dithietane to be reported was the dithiatopazine, formed by intramolecular photodimerization of a bis(thionolactone):<ref>{{cite journal |last=Nicolaou |first=KC |author2=Hwang, CK |author3=Duggan, ME |author4= Carroll, PJ |title=Dithiatopazine. The first stable 1,2-dithietane |journal =J. Am. Chem. Soc.|year=1987|volume=109|issue=12|pages=3801–3802|doi=10.1021/ja00246a059|bibcode=1987JAChS.109.3801N }}</ref> frameless|center|200px|Structure of dithiatopazine Heating dithiatopazine generates eliminates the sulfur atoms as unstable disulfur, and other dithietanes are presumed to decompose similarly.{{sfn|Zoller|1996|p=1124}}

A stable 1,2-dithietane derivative is ''trans''-3,4-diethyl-1,2-dithietane 1,1-dioxide: frameless|center|130px|Structure of ''trans''-3,4-diethyl-1,2-dithietane 1,1-dioxide, the dimer of the onion lachrymatory agent That compound is formed by the spontaneous dimerization of syn-propanethial-S-oxide, the lachrymatory agent found in onions.<ref>{{cite journal |last=Block |first=E |author2=Bazzi, AA |author3=Revelle, LK |title=The chemistry of sulfines. 6. Dimer of the onion lachrymatory factor: the first stable 1,2-dithietane derivative |journal =J. Am. Chem. Soc.|year=1980|volume=102|issue=7|pages=2490–2491|doi=10.1021/ja00527a074|bibcode=1980JAChS.102.2490B }}</ref>

Another derivative class of 1,2-dithietanes are the 1,2-dithietes, containing two adjacent sulfur atoms and two trigonal planar carbon centers.

== 1,3-Dithietanes == In 1,3-dithietanes, the sulfur atoms are non-adjacent.<ref>{{cite journal |last=Luh |first=TY |author2=Leung, MK| title =Product Subclass 2: 1,3-Dithietanes |journal =Sci. Synth. |year=2007 |volume=30 |pages=203–219}}</ref> The functional group is used industrially in various biocides. Examples include the antibiotic Cefotetan and the pesticide Fosthietan.{{sfn|Zoller|1996|p=1137}}

1,3-Dithietane itself, a colorless, easily sublimed, crystalline, unpleasant-smelling solid with melting point 105-106&nbsp;°C, was first prepared in 1976 by reaction of bis(chloromethyl) sulfoxide with sodium sulfide followed by THF-borane reduction of the first formed 1,3-dithietane 1-oxide:<ref>{{cite journal |last=Block |first=E |author2=Corey, ER |author3=Penn, RE |author4=Renken, TL |author5= Sherwin, PF |title=1,3-Dithietane |journal=J. Am. Chem. Soc.|year=1976|volume=98|issue=18|pages=5715–5717|doi=10.1021/ja00434a061|bibcode=1976JAChS..98.5715B }}</ref><ref>{{cite journal |last=Block |first=E |author2=Corey, ER |author3=Penn, RE |author4=Renken, TL |author5=Sherwin, PF |author6=Bock, H |author7=Hirabayashi, T |author8=Mohmand, S |author9= Solouki, B |title=Synthesis and Thermal Decomposition of 1,3-Dithietane and its ''S''-Oxides |journal=J. Am. Chem. Soc.|year=1982|volume=104|issue=11|pages=3119–3130|doi=10.1021/ja00375a030}}</ref> 400 px|center|Synthesis of 1,3-dithietane

Carbon-substituted 1,3-dithietanes are well known, with the first examples being described as early as 1872. Examples include 2,2,4,4-tetrachloro-1,3-dithietane, the photochemically-formed dimer of thiophosgene, and tetrakis(trifluoromethyl)-1,3-dithietane, [(CF<sub>3</sub>)<sub>2</sub>CS]<sub>2</sub>.<ref>{{OrgSynth | author = Van Der Puy, M. | author2 = Anello, L. G. | title= Hexafluoroacetone | collvol = 7 | collvolpages = 251. | year =1990 |prep = CV7P0251}}</ref> Symmetric 1,3{{nbh}}dithietanes are preferably synthesized from thiocarbonyl dimerization.{{sfn|Zoller|1996|p=1132}} Heating or irradiating dithietanes results in "dedimerization" to give the corresponding thiocarbonyl compounds.{{sfn|Zoller|1996|p=1125}}

Oxidized forms of 1,3-dithietane are well known, although they are often not prepared from the dithietane. Examples include the so-called zwiebelanes (2,3-dimethyl-5,6-dithiabicyclo[2.1.1]hexane ''S''-oxides) from onion volatiles<ref>{{cite journal |last=Block |first=E |author2=Thiruvazhi, M |author3=Toscano, PJ |author4=Bayer, T |author5=Grisoni, S |author6= Zhao, SH |title=''Allium'' Chemistry: Structure, Synthesis, Natural Occurrence in Onion (''Allium cepa''), and Reactions of 2,3-Dimethyl-5,6-dithiabicyclo[2.1.1]hexane ''S''-Oxides |journal =J. Am. Chem. Soc.|year=1996|volume=118|issue=12|pages=2790–2798|doi=10.1021/ja951134t|bibcode=1996JAChS.118.2790B }}</ref> and 1,3-dithietane 1,1,3,3-tetraoxide, the so-called sulfene dimer:<ref>{{cite journal |last=Opitz|first=G |author2=Mohl, HR|title=Disulfene |journal =Angew. Chem. Int. Ed.|year=1969|volume=8|issue=1|pages=73|doi=10.1002/anie.196900731}}</ref> [[File:1,3-Dithietanes.svg|thumb|center|425px|Left: thiophosgene dimer, 2,2,4,4-tetrachloro-1,3-dithietane; center: a zwiebelane, found in onion volatiles; right: sulfene dimer]] They are more acidic than acyclic disulfones, but even so are hard to alkylate.{{sfn|Zoller|1996|p=1129}}

In the desaurins, each carbon atom is attached to alkylidene substituents (i.e., a double bond).

==References== {{Reflist}}

Category:Dithietanes