A compound of the formula ##STR1## wherein R.sub.1 represents a hydrogen atom or a lower alkyl group; R.sub.2 and R.sub.5, independently from each other, represent a hydrogen atom, a halogen atom or a lower alkyl group; one of R.sub.3 and R.sub.4 represents an imido group of the formula ##STR2## in which Y represents a 1,2-phenylene, 1,2-naphthylene, 2,3-naphthylene or 1,8-naphtylene group optionally containing at least one substituent, and the other represents a hydrogen atom, a halogen atom or a lower alkyl group; R.sub.6 represents a hydrogen atom, a halogen atom, a lower alkyl group or a lower alkoxy group; and X represents a halogen atom; with the proviso that when R.sub.3 represents the imido group, R.sub.2 represents a hydrogen or halogen atom. This compound can be prepared by reacting a corresponding quinaldine derivative with a tetrahalophthalic acid or a reactive derivative thereof. A yellow organic pigment comprising this compound as a coloring ingredient is useful for coloring polymeric materials.