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6,6'-Dibromoindigo

6,6'-Dibromoindigo is an organic compound with the formula (BrC₆H₃C(O)CNH)₂. A deep purple solid, the compound is also known as Tyrian purple, a dye of historic significance. Presently, it is only a curiosity, although the related derivative indigo is of industrial significance. The molecule consists of a pair of monobrominated indole rings linked by a carbon-carbon double bond. It is produced by molluscs of the Muricidae species.^[1]

The pure compound has semiconductor properties in the thin film phase, which is potentially useful for wearable electronics, and has better performance than the parent indigo in this context.^[2]^[3]

Biosynthesis[edit]

The biosynthesis proceeds by the intermediacy of tyrindoxyl sulphate.^[4]

6BrIG can also be produced enzymatically in vitro from the amino acid tryptophan. The sequence begins with bromination of the benzo ring followed by conversion to 6-bromoindole. Flavin-containing monooxygenase then couples two of these indole units to give the dye.

Chemical synthesis[edit]

The main chemical constituent of the Tyrian dye was discovered by Paul Friedländer in 1909 to be 6,6′-dibromoindigo, derivative of indigo dye, which had been synthesized in 1903.^[5]^[6] Although the first chemical synthesis was reported in 1914, unlike indigo, it has never been synthesized at commercial level.^[7]^[8] An efficient protocol for laboratory synthesis of dibromoindigo was developed in 2010.^[9]

References[edit]

^ McGovern, Patrick E.; Michel, R. H. (1990). "Royal Purple dye: The chemical reconstruction of the ancient Mediterranean industry". Accounts of Chemical Research. 23 (5): 152–158. doi:10.1021/ar00173a006.
^ Pandolfi, Lorenzo; Rivalta, Arianna; Salzillo, Tommaso; Giunchi, Andrea; D’Agostino, Simone; Della Valle, Raffaele G.; Brillante, Aldo; Venuti, Elisabetta (13 August 2020). "In Search of Surface-Induced Crystal Structures: The Case of Tyrian Purple". The Journal of Physical Chemistry C. 124 (32): 17702–17710. doi:10.1021/acs.jpcc.0c05186. hdl:11585/786088.
^ "Tyrian purple: The lost ancient pigment that was more valuable than gold". www.bbc.com.
^ Valles-Regino, Roselyn; Mouatt, Peter; Rudd, David; Yee, Lachlan; Benkendorff, Kirsten (2016). "Extraction and Quantification of Bioactive Tyrian Purple Precursors: A Comparative and Validation Study from the Hypobranchial Gland of a Muricid Dicathais orbita". Molecules. 21 (12): 1672. doi:10.3390/molecules21121672. PMC 6273837. PMID 27929402.
^ Friedlaender, P. (1909). "Zur Kenntnis des Farbstoffes des antiken Purpurs aus Murex brandaris" [Towards understanding the ancient purple dye from Murex brandaris]. Monatshefte für Chemie. 30 (3): 247–253. doi:10.1007/BF01519682. S2CID 97865025.
^ Sachs, Franz; Kempf, Richard (1903). "Über p-Halogen-o-nitrobenzaldehyde". Berichte der Deutschen Chemischen Gesellschaft. 36 (3): 3299–3303. doi:10.1002/cber.190303603113.
^ "Indigo". Encyclopædia Britannica. Vol. V (15th ed.). Chicago, IL: Encyclopædia Britannica, Inc. 1981. p. 338. ISBN 0-85229-378-X.
^ Cooksey, C.J. (2001). "Tyrian purple: 6,6'-dibromoindigo and related compounds" (PDF). Molecules. 6 (9): 736–769. doi:10.3390/60900736. S2CID 5592747.
^ Wolk JL, Frimer AA (August 2010). "A simple, safe and efficient synthesis of Tyrian purple (6,6'-dibromoindigo)". Molecules. 15 (8): 5561–5580. doi:10.3390/molecules15085561. PMC 6257764. PMID 20714313.

A kind of preparation method of bromindigo dyestuff

Indigo and Bromo Indigo. The Plant and Animal Kingdoms