Thioindigo

Thioindigo

Names
IUPAC name 2-(3-Oxo-1-benzothiophen-2(3H)-ylidene)-1-benzothiophen-3(2H)-one
Other names DyStar, C.I. Vat Red 41, C.I. 73 300
Identifiers
CAS Number	522-75-8
3D model (Jmol)	Interactive image
ChemSpider	4527286
ECHA InfoCard	100.007.580
PubChem	3033973
InChI InChI=1S/C16H8O2S2/c17-13-9-5-1-3-7-11(9)19-15(13)16-14(18)10-6-2-4-8-12(10)20-16/h1-8H/b16-15+ Key: JOUDBUYBGJYFFP-FOCLMDBBSA-N InChI=1/C16H8O2S2/c17-13-9-5-1-3-7-11(9)19-15(13)16-14(18)10-6-2-4-8-12(10)20-16/h1-8H/b16-15+ Key: JOUDBUYBGJYFFP-FOCLMDBBBL
SMILES O=C3c4ccccc4S/C3=C2/Sc1ccccc1C2=O
Properties
Chemical formula	C16H8O2S2
Molar mass	296.36 g·mol^−1
Appearance	Red solid
Melting point	280 °C (536 °F; 553 K)
Solubility in water	Insoluble
Solubility in ethanol, xylene	Soluble
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
verify (what is  ?)
Infobox references

Thioindigo is an organosulfur compound that is used to dye polyester fabric. A synthetic dye, thioindigo is related to the plant-derived dye indigo, replacing two NH groups with two sulfur atoms.

Thioindigo is generated by the alkylation of the sulfur in thiosalicylic acid with chloroacetic acid. The resulting thioether cyclizes to 2-hydroxythianaphthene, which is easily converted to thioindigo.^[1] The related compound 4,7,4',7'-tetrachlorothioindigo, also a commercially important dye, can be prepared by chlorination of thioindigo.

References

1. Elmar Steingruber "Indigo and Indigo Colorants" in Ullmann's Encyclopedia of Industrial Chemistry, 2004, Wiley-VCH, Weinheim. doi: 10.1002/14356007.a14_149.pub2