| Thioindigo | |
|---|---|
|
Other names
DyStar, C.I. Vat Red 41, C.I. 73 300 |
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| Identifiers | |
| CAS number | 522-75-8 = |
| Properties | |
| Molecular formula | C16H8O2S2 |
| Molar mass | 296.37 |
| Appearance | red solid |
| Melting point |
280 °C, 553 K, 536 °F |
| Solubility in water | polar organic solvents |
| (verify) (what is: /?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
Thioindigo is an organosulfur compound that is used for dying polyester fabrics. It is related to the more common dye indigo by replacement of two NH groups with sulfur atoms.
It is prepared by S-alkylation of thiosalicylic acid with chloroacetic acid. The resulting thioether cyclizes to 2-hydroxythionaphthene, which dimerizes.[1] The related compound 4,7,4',7'-tetrachlorothioindigo, also a commercially important dye, can be prepared by chlorination of thioindigo.