HS(=O)OH, sulfinic acid, and its
S-hydrocarbyl derivatives, e.g.
(CH3)2CHS(=O)OH
propane-2-sulfinic acid.
Source:
PAC, 1995, 67, 1307
(Glossary of class names of organic compounds and reactivity intermediates based on
structure (IUPAC Recommendations 1995))
on page 1369