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IUPAC name
Other names
Thioformaldehyde trimer, Trimethylentrisulfide, Trimethylene trisulfide, Trithioformaldehyde, 1,3,5-Trithiacyclohexane, sym-Trithiane, Thioform, s-Trithiane
291-21-4 N
ChEBI CHEBI:39196 YesY
ChemSpider 8907 YesY
EC Number 206-029-7
Jmol 3D model Interactive image
PubChem 9264
Molar mass 138.27
Appearance Colourless solid
Density 1.6374 g/cm3[1]
Melting point 215 to 220 °C (419 to 428 °F; 488 to 493 K)
Slightly soluble
Solubility Benzene
Vapor pressure {{{value}}}
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YesYN ?)
Infobox references

1,3,5-Trithiane is the chemical compound with the formula (CH2S)3. This heterocycle is the cyclic trimer of the otherwise unstable species thioformaldehyde. It consists of a six-membered ring with alternating methylene bridges and thioether groups. It is prepared by treatment of formaldehyde with hydrogen sulfide.[2] It is the trimer of thioformaldehyde.

Trithiane is a building block molecule in organic synthesis, being a masked source of formaldehyde. In one application, it is deprotonated with organolithium reagents to give the lithium derivative, which can be alkylated.[3]

(CH2S)3 + RLi → (CH2S)2(CHLiS) + RH
(CH2S)2(CHLiS) + R’Br → (CH2S)2(CHR’S) + LiBr
(CH2S)2(CHR’S) + H2O → R’CHO + ….

Trithiane is the dithioacetal of formaldehyde. Other dithioacetals undergo similar reactions to the above.

It is also a precursor to other organosulfur reagents. For example, chlorination in the presence of water affords the chloromethyl sulfonyl chloride:[4]

(CH2S)3 + 9 Cl2 + 6 H2O → 3 ClCH2SO2Cl + 12 HCl


Trithiane is the parent of a class of heterocycles called trithianes. The species often arise from thiation of ketones and aldehydes. The incipient thioketones and thioaldehydes suffer trimerization. The reaction is reversed thermally.



  1. David R. Lide, ed. Handbook of Chemistry and Physics, 85th Edition, Internet Version 2005. CRC Press, 2005.
  2. Bost, R. W.; Constable, E. W. "sym-Trithiane" Organic Syntheses, Collected Volume 2, p.610 (1943). http://orgsyn.org/Content/pdfs/procedures/CV2P0610.pdf
  3. Seebach, D.; Beck, A. K. “Aldehydes From sym-Ttrithiane: n-Pentadecanal” Organic Syntheses, Collected Volume 6, p.869 (1988). http://orgsyn.org/Content/pdfs/procedures/CV6P0869.pdf
  4. Paquette, L. A.; Wittenbrook, L. S. “2-Chlorothiirane 1,1-Dioxide” Organic Syntheses, Collected Volume 5, p.231 (1973). http://orgsyn.org/Content/pdfs/procedures/CV5P0231.pdf