Disclosed are compositions comprising one or more compounds characterized by the formula: ##STR1## wherein Ar is an aromatic moiety having at least one substituent which is an acid group or salt thereof; X is a hydrocarbyl, carboxylic acid ester, sulfonic acid ester, carboxylic acid amide or sulfonic acid amide group; each Y is independently a hydrocarbyl, halogen, hydrocarbyloxy, carboxylic acid ester, sulfonic acid ester, carboxylic acid amide, imidazolone, sulfonic acid amide or nitro group; and a is 1, 2 or 3. Also disclosed is a process for preparing azo dyes which comprises coupling (i) at least one diazonium component of one or more aromatic amines containing at least one sulfonic acid group or carboxylic acid group, or salts thereof; with (ii) at least one coupling component represented by the formula: ##STR2## wherein X, Y and a are as defined above. The dye compositions prepared by this process and the azo pigments derived from such dyes are also disclosed. Paint, ink and plastic compositions containing the foregoing pigments compositions are disclosed.