syn-PropanethialS-oxide (or(Z)-propanethialS-oxide), a member of a class oforganosulfur compounds known asthiocarbonylS-oxides (formerly "sulfines"),[2] is a volatile liquid that acts as alachrymatory agent (triggers tearing and stinging on contact with the eyes).
The chemical is released fromonions,Allium cepa, as they are sliced. The release is due to the breaking open of the onion cells, which releasesenzymes calledalliinases. Alliinases then break downamino acidsulfoxides, generatingsulfenic acids. A specific sulfenic acid,allicin or 1-propenesulfenic acid, is rapidly rearranged by another enzyme, the lachrymatory factor synthase (LFS), to givesyn-propanethialS-oxide.[3] Vapors from this volatile liquid induce tearing.[4]
^Zwanenburg, B. (2004). "Thioaldehyde and ThioketoneS-Oxides andS-Imides (Sulfines and Derivatives)". In Padwa, A. (ed.).Heteroatom Analogues of Aldehydes and Ketones. Science of Synthesis. Vol. 27. pp. 135–176.ISBN978-1-58890-204-7.
^Kubec, R.; Cody, R. B.; Dane, A. J.; Musah, R. A.; Schraml, J.; Vattekkatte, A.; Block, E. (2010). "Applications of DART Mass Spectrometry in Allium Chemistry. (Z)-ButanethialS-Oxide and 1-Butenyl Thiosulfinates and theirS-(E)-1-ButenylcysteineS-Oxide Precursor fromAllium siculum".Journal of Agricultural and Food Chemistry.58 (2):1121–1128.doi:10.1021/jf903733e.PMID20047275.
^Block, E; Bazzi, AA; Revelle, LK (1980). "The chemistry of sulfines. 6. Dimer of the onion lachrymatory factor: the first stable 1,2-dithietane derivative".J. Am. Chem. Soc.102 (7):2490–2491.Bibcode:1980JAChS.102.2490B.doi:10.1021/ja00527a074.
