TH6693A - The use of N-substituted-5,6-dihydroxyindole as a hair coloring agent. - Google Patents

Abstract

The hair dyeing process involves using N-substituted-5,6-dihydroxyindole in solution as a hair dye, in combination with a pre-treatment of the hair with a solution containing water-soluble salts of various metals. This dyeing process produces hair colors ranging from light gold to light reddish-brown to dark reddish-brown to black.

Claims (14)

1. A hair dyeing method consisting of exposure of the hair to a solution of aqueous dissolved metal ions, followed by exposure to a solution of N-substituted-5,6-dihydroxyindole, or vice versa, where the chosen substituent group at the nitrogen atom can be any of the C1-C8 alkyl, hydroxyalkyl, aminoalkyl, aminoaryl, and nitroaryl groups, which may have 1 to 3 attached substituent groups. 2. The method according to claim 1 involves selecting water-soluble salts from the group containing salts of Cr, Ag, Au, Pb, Pd, Co, Cu, Ni, Bi, Mn, Fe, Ti, Sn, or Zn, and using solutions at concentrations ranging from approximately 0.001% to approximately 2.0% by weight to stain at a pH of approximately pH 3 to approximately pH 11, before treating these hairs with the aforementioned N-substituted-5,6-dihydroxyin dole solution. 3. The method according to claim 1, which uses a solution of N-substituted ted-5,6-dihydroxyindole for staining at approximately pH 3 to pH 12. 4. Method of Claim 2, which involves taking the hair to be dyed and performing the following steps: (1) treating with a mixture of water-soluble salts of Cr, Ag, Au, Pb, Pd, Co, Cu, Ni, Bi, Mn, Fe, Ti, Sn, or Zn, and using a solution of a concentration of approximately 0.001% to approximately 2.0% by weight of dye at a pH of approximately 3 to approximately 11, (2) then treating with a solution of the above N-substituted-5,6-dihydroxyin dole at a pH of approximately 3 to approximately 12, either by washing or not washing the first dyeing solution. 5. The method of claim 4, which reverses the order of steps (1) and (2). 6. The method of claim 1 is followed by the application of this hair to a bleaching agent solution, at a concentration of approximately 1% to 6%, at a pH of approximately 6 to 11, for 5 to 30 minutes to achieve a shiny effect or remove the color from the hair. 7. Method of claim number 6, where the bleaching agent is H2O2. 8. Method of claim 6, in which the bleaching agent is a salt of SO2, such as sodium or potassium bisulfite, or a sulfhydryl compound, such as thioglycolic acid, or a potassium, sodium, or ammonium salt of this compound. 9. Method of Claim 1, in which the substituents in N-substituted ted-5,6-dihydroxyindole are methyl, isodpropyl, aminophenyl, or nitrophenyl, and each benzene ring may contain 1 to 3 substituents. 10. Method of Claim 1, in which N-substituted ted-5,6-dihydroxyindole is N-methyl-5,6-dihydroxyindole. 11. Method of Claim 1, in which N-substituted ted-5,6-dihydroxyindole is N-isopropyl-5,6-dihydroxyindole. 12. Method of Claim 1, in which N-substituted ted-5,6-dihydroxyindole is N-(2,4-dinitrophenyl)-5,6-dihydroxyindole 13. Method of Claim 1, in which N-substituted ted-5,6-dihydroxyindole is N-(4-nitrophenyl)-5,6-dihydroxyindole 14. Method of Claim 1, in which N-substituted ted-5,6-dihydroxyindole is N-(4-aminophenyl)-5,6-dihydroxyindole (Claim 12, 2 pages, - Figure)