2,2,4,4,6,6-Hexamethyl-1,3,5-trithiane


Trithioacetone or 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 is a stable cyclic trimer of thioacetone, which by itself is an unstable compound. In contrast, the analogous trioxane compound, 2,2,4,4,6,6-hexamethyl-1,3,5-trioxane, with oxygen atoms in place of the sulfur atoms, seems to be unstable, while its corresponding monomer acetone 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 the 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

The compound is found on some flavoring agents. Its FEMA number is 3475.

Toxicity

The LD50 for mice is 2.4 g/kg.