sulfonphthaleins

https://doi.org/10.1351/goldbook.S06122
3,3-Bis(hydroxyaryl)-3H-2,1-benzoxathiole S,S-dioxides, formed by condensation of o-sulfobenzoic acid with @[email protected] or related compounds, e.g.
S06122.png
See:
phenols
,
phthaleins
Source:
PAC, 1995, 67, 1307. (Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)) on page 1370 [Terms] [Paper]