Nitro-phthalides, their manufacture and their use in recording systems

Abstract

Nitro-phthalides of the formula ##STR1## in which E is a radical of the formula ##STR2## X and X' each represents alkyl with 1 to 12 carbon atoms, alkoxy with 1 to 12 carbon atoms or acyloxy with 2 to 12 carbon atoms, and X may also be hydrogen. Z represents hydrogen, alkyl having 1 to 12 carbon atoms or phenyl, Y represents hydrogen, alkyl having 1 to 12 carbon atoms, benzyl or cyanoethyl, R.sub.1, R.sub.2, R.sub.1 ' and R.sub.2 ', independently of the other, represents 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 and the benzene ring B may be further substituted by halogen, nitro or an amino group optionally substituted by alkyl with 1 to 6 carbon atoms. The nitro-phthalides are particularly useful as color formers which give intense green, blue-green or blue colors when they are brought into contact with an electron-accepting co-reactant.

Dependencies are inferred from the claim text.