Abstract: A thermographic recording process in which a dye is produced by bringing image-wise into reactive contact with the aid of heat an organic acid-reacting compound with a dye precursor compound corresponding to the following general formula:X = Ar - CH = N - R.sub.1wherein:Ar represents a bivalent aromatic nucleus,R.sub.1 represents an aryl group andX represents a ##STR1## group wherein each of R.sub.2 and R.sub.3 (same or different) represents an alkyl group, a cycloalkyl group, an aralkyl group, or an aryl group or R.sub.2 and R.sub.3 together represent the necessary atoms to close a nitrogen-containing heterocyclic nucleus.

Abstract: A thermographic recording process in which a dye is produced by bringing image-wise into reactive contact with the aid of heat a dye precursor compound and a compound with acid reaction corresponding to the following general formula: ##EQU1## wherein : Z represents the necessary atoms to close an unsubstituted benzene nucleus, a halogen-substituted benzene nucleus or a nitro-substituted benzene nucleus, andR represents an unsubstituted aliphatic group containing at least 4 carbon atoms, a cycloaliphatic group or an aliphatic group substituted with hydroxyl, with an etherified hydroxyl group or with an acyloxy grup.

Abstract: A thermographic recording process in which a methine dye is produced by bringing image-wise into reactive contact with the aid of heat an acid-reacting compound with a dye precursor compound corresponding to the following general formula: ##EQU1## wherein: R.sub.1 represents (1) a substituted aryl group, at least one substituent of the substituted aryl group being an ether group R.sub.6 --O-- in which R.sub.6 represents a hydrocarbon group including a substituted hydrocarbon group or (2) a heterocyclic group including a substituted heterocyclic group,R.sub.2 represents a substituted aryl group, at least one substituent of the substituted aryl group, being an ether group R.sub.6 --O--, in which R.sub.6 represents a hydrocarbon group, including a substituted hydrocarbon group, a heterocyclic group including a substituted heterocyclic group, or a ##EQU2## group in which Z represents the necessary atoms to close a heterocyclic nucleus including a substituted heterocyclic nucleus,R.sub.