Thioindigo

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Skeletal formula of thioindigo
Ball-and-stick model of the thioindigo molecule
Names
Preferred IUPAC name -3H,3′H--3,3′-dione
Other names DyStar, C.I. Vat Red 41, C.I. 73 300
Identifiers
CAS Number
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.007.580
PubChem CID
UNII
CompTox Dashboard (EPA)
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+ ☒NKey: JOUDBUYBGJYFFP-FOCLMDBBSA-N ☒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 , 100 kPa). ☒N verify (what is checkY☒N ?) 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 to create a shade of pink.

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. The related compound 4,7,4',7'-tetrachlorothioindigo, also a commercially important dye (Pigment Red 88), 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