Synthesen mit Nitrilen, XLVIII Merocyanine und Oxonole von Phenyl-indanyliden-acetonitrilen / Syntheses with Nitriles, XLVIII Merocyanines and Oxonoles of Phenyl-indanylidene-acetonitriles

Abstract

2-Dicyanomethylene-1,3-indandione reacts with 2,6-disubstituted anilines to give aminophenyl-1,3-dioxo-2-indanyl-malononitriles. By heating or by photolysis HCN is eliminated from the adducts and deeply coloured aminophenyl-1,3-dioxo-2-indanylideneacetonitriles are formed. They are classified as merocyanine type polymethines. The irreversible change in colour occurs at temperatures above 70 °C, the adducts are therefore capable of indicating temperatures. Reaction of phenols with 2-dicyanomethylene-1,3-indandione yields hydroxyphenyl-1,3-dioxo-2-indanylideneacetonitriles, oxonole type polymethines with the properties of pH-indicators.