| Popis: |
The identification of 6, 6′-dibromoindirubin as a component of Tyrian purple has been confirmed by a practical synthesis. Two monobromoindirubins, which could be minor components, have also been synthesised. These compounds have been fully characterised by UV/vis, NMR, IR and MS data. However, the use of UV/vis absorption maxima in solution is shown to be an unreliable identification tool, being solvent dependent. MS cannot distinguish 6, 6′-dibromoindirubin from 6, 6′-dibromo-indigotin, the major component; solution NMR is precluded by lack of solubility and the colorant is best characterised by HPLC. The first investigation of the composition of Tyrian purple from Nucella lapillus is reported. |
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