Thial

In organic chemistry, a thial or thioaldehyde is a functional group which is similar to an aldehyde, RC(O)H, in which a sulfur (S) atom replaces the oxygen (O) atom of the aldehyde (R represents an alkyl or aryl group).

Unhindered thioaldehydes are generally too reactive to be isolated — for example, thioformaldehyde, H2C=S, condenses to the cyclic trimer 1,3,5-trithiane.

Thioacrolein, H2C=CHCH=S, formed by decomposition of allicin from garlic, undergoes a self Diels-Alder reaction giving isomeric vinyldithiins.

[1][2] While thioformaldehyde is highly reactive, it is found in interstellar space along with its mono- and di-deuterated isotopologues.

[4] In early work, the existence of thioaldehydes was inferred by trapping processes.