Syn-Propanethial-S-oxide

syn-Propanethial S-oxide (or (Z)-propanethial S-oxide), a member of a class of organosulfur compounds known as thiocarbonyl S-oxides (formerly "sulfines"),^[2] is a volatile liquid that acts as a lachrymatory agent (triggers tearing and stinging on contact with the eyes).

syn-Propanethial S-oxide

Names
IUPAC name (Z)-propylidene-λ4-sulfanone[1]
Other names Thiopropanal S-oxide 1-Sulfinylpropane
Identifiers
CAS Number	32157-29-2 Y
3D model (JSmol)	Interactive image
ChemSpider	390214 Y
PubChem CID	441491
UNII	94Z73U61UH Y
CompTox Dashboard (EPA)	DTXSID50954029
InChI InChI=1S/C3H6OS/c1-2-3-5-4/h3H,2H2,1H3 Y Key: BAZSXBOAXJLRNH-UHFFFAOYSA-N Y InChI=1/C3H6OS/c1-2-3-5-4/h3H,2H2,1H3 Key: BAZSXBOAXJLRNH-UHFFFAOYAF
SMILES O=S=C/CC
Properties
Chemical formula	C3H6OS
Molar mass	90.14 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Onion release

The chemical is released from onions, Allium cepa, as they are sliced. The release is due to the breaking open of the onion cells, which releases enzymes called alliinases. Alliinases then break down amino acid sulfoxides, generating sulfenic acids. A specific sulfenic acid, allicin or 1-propenesulfenic acid, is rapidly rearranged by another enzyme, the lachrymatory factor synthase (LFS) to give syn-propanethial S-oxide.^[3] Vapors from this volatile liquid induces tearing.^[4]

Related compounds

A structurally related lachrymatory compound, syn-butanethial S-oxide, C₄H₈OS, has been found in another genus Allium plant, Allium siculum.^[5]

Structure of trans-3,4-diethyl-1,2-dithietane 1,1-dioxide

Propanethial S-oxide forms a stable thiosultone dimer, trans-3,4-diethyl-1,2-dithietane 1,1-dioxide.^[6]