{{Chembox | ImageFile = 2,2,4,4,6,6-Hexamethyl-1,3,5-trithiane flat.png | ImageCaption = | PIN = Hexamethyl-1,3,5-trithiane | OtherNames = Trithioacetone<ref name=nih2020/> | Section1 = {{Chembox Identifiers | PubChem = 13233 | CASNo = 828-26-2 | ChemSpiderID = 12678 | EC_number = 212-582-5 | UNII = L0ME5B2ZWY | DTXSID = DTXSID2047723 | ChEMBL = 3187896 | StdInChI = 1S/C9H18S3/c1-7(2)10-8(3,4)12-9(5,6)11-7/h1-6H3 | StdInChIKey = NBNWHQAWKFYFKI-UHFFFAOYSA-N | SMILES = C1(SC(SC(S1)(C)C)(C)C)(C)C | Beilstein = 5-19-09-00119 }} | Section2 = {{Chembox Properties | C=9|H=18|S=3 | Appearance = | Odor = Unpleasant, sulfurous | Density = 1.0660 to 1.0700 g/mL<ref name=tcicat/> | Solubility = | SolubleOther = | MeltingPt = 21.8°C<ref name=pubchem/> | BoilingPt = 107°C/10mmHg<ref name=tcicat/> | Viscosity = | RefractIndex = 1.5390 to 1.5430<ref name=tcicat/> | VaporPressure = | MagSus = }} | Section4 = {{Chembox Thermochemistry | DeltaHf = | DeltaHc = | Entropy = }} | Section7 = {{Chembox Hazards | GHSPictograms = {{GHS07}} | GHSSignalWord = Warning | HPhrases = {{H-phrases|315|319|335}} | PPhrases = {{P-phrases|261|264|271|280|302+352|304+340|305+351+338|312|321|332+313|337+313|362|403+233|405|501}} }} }}
'''Trithioacetone''' ('''2,2,4,4,6,6-hexamethyl-1,3,5-trithiane''') is an organic chemical with formula {{chem|C|9|H|18|S|3}}. Its covalent structure is {{chem|[–C(CH|3|)|2|–S–]|3}}, that is, a six-membered ring of alternating carbon and sulfur atoms, with two methyl groups attached to each carbon.<ref name=bres2009/><ref name=tcicat/> It can be viewed as a derivative of 1,3,5-trithiane, with methyl-group substituents for all of the hydrogen atoms in that parent structure.
The compound Trithioacetone is a stable cyclic trimer of thioacetone (propane-2-thione), which by itself is an unstable compound.<ref name=lips1970/><ref name=shar1979/> In contrast, the analogous trioxane compound, 2,2,4,4,6,6-hexamethyl-1,3,5-trioxane (Triacetone), with oxygen atoms in place of the sulfur atoms, seems to be unstable, while its corresponding monomer acetone (2-propanone) is stable.
==Synthesis== Trithioacetone was first made in 1889 by Baumann and Fromm, by reaction of hydrogen sulfide with acetone.<ref name=shar1979/> In the presence of an acidified {{chem|ZnCl|2}} catalyst at 25 °C, one obtains a product that is 60–70% trithioacetone, 30–40% of 2,2-propanedithiol, and small amounts of two isomeric impurities, 3,3,5,5,6,6-hexamethyl-1,2,4-trithiane and 4-mercapto-2,2,4,6,6-pentamethyl-1,3-dithiane.<ref name=shar1979/> The product can also be obtained by pyrolysis of allyl isopropyl sulfide.<ref name=bail1965/><ref name=bohme1942/>
==Reactions== Pyrolysis of trithioacetone at 500–650 °C and 5–20 mm of Hg gives thioacetone, that can be collected by a cold trap at −78 °C. 300px|center|Pyrolysis/polymerization between trithioacetone (left) and thioacetone (right).
==Uses== Trithioacetone is found in some flavoring agents. Its FEMA number is 3475.<ref name=mora1980/><ref name=who/><ref name=ohlo1979/><ref name=euro2012/>
==Toxicity== The LD<sub>50</sub> (oral) in mice is 2.4 g/kg.<ref name=mora1980/><ref name=pubchem/>
==See also== * 2,4,6-trimethyl-1,3,5-trithiane * Hexamethylcyclotrisiloxane, an analog with a silicon-oxygen ring instead of a carbon-sulfur one. * Hexamethylcyclotrisilazane, with a silicon-nitrogen ring.<ref name=brew1948/> * 2,2,4,4,6,6-hexamethyl-1,3,5-triselena-2,4,6-tristannacyclohexane, with a tin-selenium ring.<ref name=mikh2008/><ref name=draeg1978/>
==References== <references> <ref name=brew1948>Stuart D. Brewer and Charles P. Haber (1948): "Alkylsilazanes and Some Related Compounds". ''Journal of the American Chemical Society'', volume 70, issue 11, pages 3888–3891. {{doi|10.1021/ja01191a106}}</ref>
<ref name=mikh2008>B. M. Mikhova (2008), "NMR Data for Carbon-13 – C6H18Se3Sn3" in ''Landolt-Börnstein – Group III Condensed Matter'', volume 35 ''Nuclear Magnetic Resonance Data'', subvolume D5, ''Organometallic Compounds''. {{doi|10.1007/978-3-540-74189-3_1362}}</ref>
<ref name=draeg1978>Martin Dräger, Axel Blecher, Hans-Jürgen Jacobsen, Bernt Krebs (1978): "Molekül- und kristallstruktur von hexamethylcyclo-tristannaselenan {{chem|[(CH|3|)|2|SnSe]|3}}". ''Journal of Organometallic Chemistry'', volume 161, issue 3, pages 319–325. {{doi|10.1016/S0022-328X(00)92243-5}}</ref>
<ref name=euro2012>EUR-Lex (2012): "[https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32012R0872 Table entry 15.009: Trithioacetone]". In ''EU Regulation No. 872/2012'', Document 32012R0872, ''Official Journal of the EU – Series L'', volume 267, pages 1–161.</ref>
<ref name=bohme1942>Horst Bohme, Hans Pfeifer, and Erich Schneider (1942): "Dimeric thioketones". ''Berichte der Deutschen Chemischen Gesellschaft'', volume 75B, issue 7, pages 900–909. {{doi|10.1002/cber.19420750722}} Note: This early report mistakes the trimer for the monomer.</ref>
<ref name=tcicat>TCI America (2020): "[https://www.tcichemicals.com/eshop/en/us/commodity/H1278/ Product H1278: 2,2,4,4,6,6-Hexamethyl-1,3,5-trithiane]". Online catalog page, accessed on 2020-01-01.</ref>
<ref name=lips1970>R. D. Lipscomb and W. H. Sharkey (1970): "Characterization and polymerization of thioacetone". ''Journal of Polymer Science – Part A: Polymer Chemistry'', volume 8, issue 8, pages 2187–2196. {{doi|10.1002/pol.1970.150080826}}</ref>
<ref name=bail1965>William J. Bailey and Hilda Chu (1965): "Synthesis of polythioacetone". ''ACS Polymer Preprints'', volume 6, pages=145–155</ref>
<ref name=shar1979>William H. Sharkey (1979): "Polymerization through the carbon-sulfur double bond". ''Polymerization'', series ''Advances in Polymer Science'', volume 17, pages 73–103. {{doi|10.1007/3-540-07111-3_2}}</ref>
<ref name=ohlo1979>G. Ohloff and I. Flament (1979): "The Role of Heteroatomic Substances in the Aroma Compounds of Foodstuffs". In ''Fortschritte der Chemie Organischer Naturstoffe'' (''Progress in the Chemistry of Organic Natural Products''), volume 36, pages 231–283. {{doi|10.1007/978-3-7091-3265-4_2}}</ref>
<ref name=who>World Health Organization (1999): "[https://who.int/food-additives-contaminants-jecfa-database/chemical.aspx?chemID=2916 Trithioacetone]{{dead link|date=December 2021|bot=medic}}{{cbignore|bot=medic}}". Online data sheet in the ''Evaluation of the Joint FAO/WHO Expert Committee on Food Additives (JECFA)''. Accessedd on 2020-01-02.</ref>
<ref name=bres2009>David S. Breslow, Herman Skolnik (2009): ''Multi-Sulfur and Sulfur and Oxygen Five- and Six-Membered Heterocycles'', Part 2; page 712. Volume 68 of ''Chemistry of Heterocyclic Compounds''. {{isbn|9780470188330}}</ref>
<ref name=nih2020>"[https://pubchem.ncbi.nlm.nih.gov/#tab/sidsrcname=ChemIDplus&query=828-26-2&input_type=text Trithioacetone]". Online chemical data sheet, accessed on 2020-01-01.</ref>
<ref name=pubchem>NCBI PubChem (2010): "[https://pubchem.ncbi.nlm.nih.gov/compound/13233 2,2,4,4,6,6-Hexamethyl-1,3,5-trithiane]". Online chemical data sheet, accessed on 2020-01-01.</ref>
<ref name=mora1980>E. J. Moran, O. D. Easterday, and B. L. Oser (1980): "Acute oral toxicity of selected flavor chemicals". ''Drug and Chemical Toxicology'', volume 3, issue 3, pages 249–258.{{PMID|7449655}} {{doi|10.3109/01480548009002221}}</ref> </references>
Category:Sulfur heterocycles