Couplers for use in oxidative hair dyeing

In a hair dyeing system wherein at least one primary intermediate is reacted with at least one coupler in the presence of an oxidizing agent to produce an oxidative hair dye, the improvement wherein the at least one coupler comprises a compound of the formula (1):

• wherein X is selected from the group consisting of halogen and R5SO4;
• R, R1 and R2 are each individually selected from the group consisting of C1 to C22 alkyl, C1 to C22 mono or dihydroxyalkyl, or two of R, R1 and R2 together with the nitrogen atom to which they are attached form a C3 to C6 saturated or unsaturated ring optionally containing in the ring one or more additional hetero atoms selected from O, S and N atoms;
• R3 and R4 are each individually selected from the group consisting of C1 to C6 alkyl, C1 to C6 hydroxyalkyl, C1 to C6 alkoxy, C1 to C6 aminoalkyl or R3 and R4 together form a C1 to C5 alkylene group;
• and R5 is selected from the group consisting of C1 to C22 alkyl and C1 to C22 mono and dihydroxyalkyl.

A hair dyeing composition comprising, in a suitable carrier or vehicle, an effective hair dyeing amount of:

• (a) at least one primary intermediate, and
• (b) at least one coupler comprising a compound of the formula (1):
• wherein X is selected from the group consisting of halogen and R5SO4;
• R, R1 and R2 are each individually selected from the group consisting of C1 to C22 alkyl, C1 to C22 mono or dihydroxyalkyl, or two of R, R1 and R2 together with the nitrogen atom to which they are attached form a C3 to C6 saturated or unsaturated ring optionally containing in the ring one or more additional hetero atoms selected from O, S and N atoms;
• R3 and R4 are each individually selected from the group consisting of C1 to C6 alkyl, C1 to C6 hydroxyalkyl, C1 to C6 alkoxy, C1 to C6 aminoalkyl, or R3 and R4 together form a C1 to C5 alkylene group;
• and R5 is selected from the group consisting of C1 to C22 alkyl and C1 to C22 mono and dihydroxyalkyl.