Sulfenic acid

[5] Sulfenic acids are produced by the enzymatic decomposition of alliin and related compounds following tissue damage to garlic, onions, and other plants of the genus Allium.

1-Propenesulfenic acid, formed when onions are cut, is rapidly rearranged by a second enzyme, the lachrymatory factor synthase, giving syn-propanethial-S-oxide.

[7] Mass spectrometry with a DART ion source were used to identify 2-propenesulfenic formed when garlic is cut or crushed and to demonstrate that this sulfenic acid has a lifetime of less than one second.

[8] The pharmacological activity of certain drugs, such as omeprazole, esomeprazole, ticlopidine, clopidogrel, and prasugrel is proposed to involve sulfenic acid intermediates.

[12] Sulfoxides can undergo thermal elimination via an Ei mechanism to yield vinyl alkenes and sulfenic acids:[13][14] Compounds which react in this manner are used as polymer stabilizers where they protects against long term heat ageing,[15] structures based on thiodipropionate esters are popular.

While sulfenic acids have the potential of exhibiting tautomerism , spectroscopic measurements as well as theoretical studies indicate that the structure on the left predominates almost exclusively.
Dioctadecyl 3,3'-thiodipropanoate: Oxidation to the sulfoxide and subsequent Ei elimination generates a sulfenic acid. This material is used as a polymer stabilizer where it protects against long term heat ageing
Cyclohexylthiophthalimide is an example of a sulfenamide , yet another derivative of sulfenic acid.