Patent ID: 8034125

Claim:
A process for dyeing keratin fibers, comprising applying to said fibers, which have optionally been pretreated with at least one reducing agent: i) a cosmetically acceptable composition comprising at least one colorless thiol/disulfide dye precursor of formula (I): [Z-A-L-S] X —(Y) y formula (I): and ii) a cosmetically acceptable composition comprising at least one colorless dye precursor of formula (II): B—X formula (II): wherein B of the at least one colorless dye precursor of formula (II) reacts chemically with A of the at least one colorless thiol/disulfide dye precursor of formula (I) to form a colored or a colored and fluorescent chromophore B—X′-A-; wherein, in formula (I) and formula (II): x is 0 or 1; y is 1 or 2; L is chosen from optionally substituted divalent C 1 -C 20 hydrocarbon-based chains, optionally interrupted and/or optionally terminated at one end with at least one group chosen from: i) divalent groups chosen from: —N(R a )—; —N + (R a )(R b )—An − ; —O—; —S—; —CO—and —SO 2 —, with R a and R b , independently of one another, each chosen from hydrogen, (C 1 -C 6 ) alkyl groups, hydroxy (C 1 -C 6 ) alkyl groups, and (di)(C 1 -C 6 ) (alkyl) amino (C 1 -C 6 ) alkyl groups, and An − chosen from anionic counterions, and ii) cationic heterocyclic and heteroaryl Het + An − groups, with An − chosen from anionic counterions and Het + chosen from saturated and unsaturated 5- to 10-membered heterocycles and saturated and unsaturated 5- to 10-membered heteroaryl groups; A and B, independently of one another, are each chosen from colorless chromophores; X and Z, independently of one another, are each chosen from chemical functional groups capable of reacting together to form a group X′; X′ is chosen from chains that allow electron transfer between chromophore A and chromophore B; Y is chosen from: i) hydrogen; ii) alkali metals; iii) alkaline-earth metals; iv) ammonium groups N + R α R β R γ R δ An″ − and phosphonium groups P + R α R β R γ R δ An″ − , with R α , R β , R γ , and R δ , independently of one another, each chosen from hydrogen and (C 1 -C 4 )alkyl groups, and An″ − chosen from anionic counterions; and v) protecting groups for a thiol function; it being understood that when y is 2, then x is zero, and when x is 1, then y is 1.