Trithioacetone Explained

Trithioacetone (2,2,4,4,6,6-hexamethyl-1,3,5-trithiane) is an organic chemical with formula . Its covalent structure is, that is, a six-membered ring of alternating carbon and sulfur atoms, with two methyl groups attached to each carbon. 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. 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. In the presence of an acidified 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. The product can also be obtained by pyrolysis of allyl isopropyl sulfide.

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.

Uses

Trithioacetone is found in some flavoring agents. Its FEMA number is 3475.

Toxicity

The LD₅₀ (oral) in mice is 2.4 g/kg.

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.
• 2,2,4,4,6,6-hexamethyl-1,3,5-triselena-2,4,6-tristannacyclohexane, with a tin-selenium ring.

References

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Notes and References

1. 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.
2. 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.
3. Martin Dräger, Axel Blecher, Hans-Jürgen Jacobsen, Bernt Krebs (1978): "Molekül- und kristallstruktur von hexamethylcyclo-tristannaselenan ". Journal of Organometallic Chemistry, volume 161, issue 3, pages 319–325.
4. EUR-Lex (2012): "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.
5. Horst Bohme, Hans Pfeifer, and Erich Schneider (1942): "Dimeric thioketones". Berichte der Deutschen Chemischen Gesellschaft, volume 75B, issue 7, pages 900–909. Note: This early report mistakes the trimer for the monomer.
6. TCI America (2020): "Product H1278: 2,2,4,4,6,6-Hexamethyl-1,3,5-trithiane". Online catalog page, accessed on 2020-01-01.
7. 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.
8. William J. Bailey and Hilda Chu (1965): "Synthesis of polythioacetone". ACS Polymer Preprints, volume 6, pages=145–155
9. William H. Sharkey (1979): "Polymerization through the carbon-sulfur double bond". Polymerization, series Advances in Polymer Science, volume 17, pages 73–103.
10. 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.
11. World Health Organization (1999): "Trithioacetone". Online data sheet in the Evaluation of the Joint FAO/WHO Expert Committee on Food Additives (JECFA). Accessedd on 2020-01-02.
12. [David S. Breslow]
13. "Trithioacetone". Online chemical data sheet, accessed on 2020-01-01.
14. NCBI PubChem (2010): "2,2,4,4,6,6-Hexamethyl-1,3,5-trithiane". Online chemical data sheet, accessed on 2020-01-01.
15. 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.