ES404841A1 - A PROCEDURE FOR THE PREPARATION OF A COLORING COMPOSITION FOR HAIR. - Google Patents

Abstract

A procedure for preparing a hair dye composition, characterized by: a) subjecting to reduction, carried out in an aqueous or alkaline hydroalcoholic medium or by catalytic hydrogenation in an appropriate organic solvent, an indoaniline of formula: ** (See formula) ** where Z represents an amino, acylamino or hydroxyl group, and R1, R2, R3, R4 and R5, the same or different, each represent a hydrogen atom or an alkyl group containing from 1 to 4 carbon atoms, being therefore minus two of these different from a hydrogen atom when Z is different from an acylamino moiety and R1 and R4 or R2 and R5 can also form, together with the carbon and nitrogen atoms to which they are attached, a dihydrooxazinic heterocycle or pyrrolínico, to obtain a diphenylamine of formula: ** (See formula) ** where R1 to R5 and Z have the meaning given above; b) separating the diphenylamide obtained in a) from the reaction medium, by filtration after neutralizing and/or cooling the reaction medium or also by concentration followed by filtration after removing the catalyst; c) optionally recrystallizing the diphenylamine prepared in b) from an appropriate solvent; d) dissolving the diphenylamine obtained in b) or in c) in an amount comprised between 0.002 and 2% by weight in an aqueous or hydroalcoholic solution that may contain other cosmetic ingredients and e) adjusting the pH in a range between 4 and 11, using a compatible acidifying or alkalizing agent, usable in cosmetics. (Machine-translation by Google Translate, not legally binding)