3-Indolyl-3-phenyl-phthalides

Abstract

Phthalides of the formula ##STR1## wherein R.sub.1 and R.sub.2, independently of the other, represent hydrogen, alkyl with 1 to 12 carbon atoms, alkoxyalkyl with 2 to 8 carbon atoms, cycloalkyl with 5 or 6 carbon atoms, benzyl or phenyl, X represents alkyl with 1 to 12 carbon atoms, alkoxy with 1 to 12 carbon atoms or acyloxy with 2 to 12 carbon atoms, Y represents alkyl with 2 to 12 carbon atoms, alkoxy with 3 to 12 carbon atoms or acyloxy with 2 to 12 carbon atoms, Z represents hydrogen, alkyl having 1 to 12 carbon atoms or phenyl, U represents alkyl having 3 to 12 carbon atoms, benzyl or cyanoethyl, or may also represent W when R.sub.1 and R.sub.2 both are benzyl, W represents hydrogen, methyl or ethyl and n is 1 or 2, the benzene rings A and B may be substituted by an amino group optionally substituted by alkyl with 1 to 6 carbon atoms and the benzene ring B may also be substituted by nitro or halogen. The phthalides are particularly useful as color formers which give intense blue colors when they are contacted with an electron-accepting co-reactant such as silton clay or a phenolic resin.

Dependencies are inferred from the claim text.