Naphthoquinone methide-type near-IR colour formers: their synthesis and oxidation properties

Abstract

New colourless naphthoquinone methide-type near-IR colour formers 1 have been synthesized, which immediately exhibit intense absorption in the near-IR region upon oxidation by p-benzoquinone. The colour development has been investigated using the stopped-flow technique. In the presence of a basic catalyst, NEt₃, oxidation of 1 gave the corresponding carbonyl cyanide derivatives 3 as the major products.