Chromogenic azaphthalides of the formula ##STR1## wherein R1 and R2 independently of each other are hydrogen, C1 C12 alkyl which is unsubstituted or substituted by {HEAD ~ halogen}, hydroxyl, cyano or lower alkoxy, or are cycloalkyl, benzyl or phenyl, or benzyl or phenyl which are substituted by halogen, nitro, cyano, lower alkyl, lower alkoxy or lower alkoxycarbonyl; or R1 and {TAIL ~ R2} together with the nitrogen atom to which they are attached are a 5 membered or 6 membered heterocyclic radical and in particular pyrrolidinyl 
Chromogenic azaphthalides of the formula # # STR1 # # wherein R1 and R2 independently of each other are hydrogen , C1 C12 alkyl which is unsubstituted or substituted by { HEAD ~ halogen } , hydroxyl , cyano or lower alkoxy , or are cycloalkyl , benzyl or phenyl , or benzyl or phenyl which are substituted by halogen , nitro , cyano , lower alkyl , lower alkoxy or lower alkoxycarbonyl ; or R1 and { TAIL ~ R2 } together with the nitrogen atom to which they are attached are a 5 membered or 6 membered heterocyclic radical and in particular pyrrolidinyl
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