Abstract: Couplers responding to the formula ##STR1## in which formula R.sub.1 represents an alkyl radical having 1 to 4 carbon atoms, R.sub.2 represents a hydrogen atom or an alkyl radical having 1 to 4 carbon atoms, and n is a number having for value 2 or 3.These couplers are particularly adapted for use in dyeing compositions containing paraphenylenediamines responding to the general formula ##STR2## or salts of the corresponding acids; formula in which R.sub.1, R.sub.2 and R.sub.3 are identical or different and represent a hydrogen atom, an alkyl radical having 1 to 2 carbon atoms or an alkoxy radical having 1 to 2 carbon atoms, R.sub.4 and R.sub.5 are identical or different and represent a hydrogen atom, an alkyl radical, hydroxyalkyl, alkoxyalkyl in which the alkoxy group comprises 1 to 2 carbon atoms, carbamylalkyl, mesylaminoalkyl, acetylaminoalkyl, ureidoaminoalkyl, carbethoxyaminoalkyl, the alkyl groups in R.sub.4 and R.sub.5 having 1 to 3 atoms of carbon, with the reservation that R.sub.1 or R.sub.