Dithiofluorescein

Dithiofluorescein
Names
	IUPAC name 3′,6′-Bis(sulfanyl)spiro[2-benzofuran-3,9′-xanthene]-1-one
	Other names 3′,6′-Dimercaptofluoran; 3′,6′-Dimercaptospiro[isobenzofuran-1(3H),9′-[9H]xanthen]-3-one; 3′,6′-Dimercapto-3H-spiro[isobenzofuran-1,9′-xanthen]-3-one; Thiofluorescein; ;
Identifiers
CAS Number	25319-73-7;
3D model (JSmol)	Interactive image;
ChemSpider	82528;
EC Number	246-830-9;
PubChem CID	91396;
CompTox Dashboard (EPA)	DTXSID3067079 ;
	InChI InChI=1S/C20H12O3S2/c21-19-13-3-1-2-4-14(13)20(23-19)15-7-5-11(24)9-17(15)22-18-10-12(25)6-8-16(18)20/h1-10,24-25H Key: QOMSORNLFVSVPW-UHFFFAOYSA-N;
	SMILES C1=CC=C2C(=C1)C(=O)OC23C4=C(C=C(C=C4)S)OC5=C3C=CC(=C5)S;
Properties
Chemical formula	C20H12O3S2
Molar mass	364.43 g·mol−1
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Dithiofluorescein (sometimes generically called thiofluorescein) is a complexometric indicator used in analytical chemistry. It changes from blue to colorless when it binds to mercury(2+) ions.^[1] It thus can indicate the endpoint in the titration of thiols using o-hydroxymercuribenzoic acid^[2] or its sodium salt.^[3] The reagent can be immobilized t in a polymer on a fiber optic, which might allow development of a detector for sulfide ions in a flow cell.^[4] Unlike fluorescein and other related fluoran dyes that have oxygen substituents on the benzene rings, dithiofluorescein, which has sulfur substituents, is not fluorescent.^[5]

References

^ Wroński, Mieczysław (1966). "Determination of thiol esters with o-hydroxymercuribenzoic acid". Analyst. 19 (2): 745–746. Bibcode:1966Ana....91..745W. doi:10.1039/AN9669100745.
^ Wroński, Mieczysław (1977). "Analytical applications of o-hydroxymercuribenzoic acid, dithiofluorescein and mercurated fluorescein". Talanta. 24 (6): 347–354. doi:10.1016/0039-9140(77)80019-2. PMID 18962100.
^ Chromý, V.; Svoboda, V. (1963). "The determination of thiomalic acid". Talanta. 10 (10): 1109–1111. doi:10.1016/0039-9140(63)80152-6.
^ Narayanaswamy, Ramaier; Sevilla, Fortunato III (1986). "Flow cell studies with immobilised reagents for the development of an optical fibre sulphide sensor". Analyst. 111 (9): 1085. Bibcode:1986Ana...111.1085N. doi:10.1039/AN9861101085.
^ Sauer, Markus; Hofkens, Johan; Enderlein, Jörg (2011). "2.2. Organic Fluorophores". Handbook of Fluorescence Spectroscopy and Imaging: From Ensemble to Single Molecules. Wiley. pp. 35–38. ISBN 978-3-527-31669-4.