Ketohydrazone dyes derived from 4-morpholino-2-naphthol and ortho-substituted anilines: Further examination of the hyperchromism induced by the 4-morpholino-2-naphthol moiety. (November 2021) - Aiken, Stuart
Abstract: A series of ketohydrazone dyes has been synthesised from 4-morpholino-2-naphthol and ortho -substituted anilines by conventional diazotisation coupling chemistry. Whilst the new, dull orange-red, dyes exhibit only a minor variation of absorption maxima across the range of substituents, they are hyperchromic relative to Sudan 1 and their none ortho -substituted analogue. Protonation of selected dye examples results in a bathochromic and hyperchromic shift in absorption maxima to afford vibrant purple-coloured protonated species. Graphical abstract: Image 1 Highlights Statements: A series of new hyperchromic ketohydrazone dyes have been synthesised. The dyes exhibit orange shades with a narrow range of absorption maxima. The dyes are more intense colouring (hyperchromic) relative to the non-ortho substituted analogue. Protonation results in a bathochromic and hyperchromic shift in λmax .