Cosmetic composition containing an n-mercaptoalkylalkanediamide or one of its cosmetically acceptable salts as reducing agent

A process for permanent deformation of hair comprising:

• (a) in a first step, reducing the disulphide bonds of keratin by application of a reducing cosmetic composition,
• (b) in a second step, reforming the said bonds by application of an oxidizing composition,
• wherein the reduction step is carried out with the aid of a reducing cosmetic composition comprising at least one compound having the following formula (I):
• ##STR19## in which:
• A denotes the divalent radical --(CH.sub.2).sub.n --, n being an integer from 2 to 5, or the divalent radical --(CH.sub.2).sub.2 --O--(CH.sub.2).sub.2 --,
• B denotes a radical, said radical being:
• (a) the divalent radical --(CH.sub.2).sub.m --, m being an integer from 1 to 7,
• (b) the divalent radical ##STR20## in which one of the groups R.sub.1, R.sub.2 and R.sub.3 denotes a radical, said radical being a linear or branched alkyl radical containing from 1 to 4 carbon atoms, methoxymethyl, phenyl, benzyl, cyclohexyl or cyclopentyl, and the other two groups are a hydrogen atom, p, q and r being 0 or an integer from 1 to 4 and wherein 1.ltoreq.p+q+r.ltoreq.4, and further wherein the p, q, or r corresponding to that radical R.sub.1, R.sub.2 or R.sub.3 which is said radical and is not a hydrogen atom is an integer from 1 to 4,
• (c) the divalent radical ##STR21## in which R.sub.4 and R.sub.5 either, being identical or different, denote a linear or branched alkyl radical containing from 1 to 4 carbon atoms, or, together with the adjacent carbon atoms, form a cyclohexane or cyclohexene ring,
• (d) the divalent radical ##STR22## in which one of R.sub.6 and R.sub.7 denotes an --NH.sub.2 radical and the other denotes a hydrogen atom;
• t being equal to 0 or 1, or
• (e) the divalent radical ##STR23## in which R.sub.8 and R.sub.9 either, being identical or different, denote a hydrogen atom or a linear or branched alkyl radical containing from 1 to 4 carbon atoms or, together with the adjacent carbon atoms, form a benzene ring,
• R and R', which are identical or different, denote:
• either a hydrogen atom or a radical, said radical being a linear or branched alkyl radical containing from I to 4 carbon atoms or a linear or branched hydroxyalkyl radical containing from 1 to 5 carbon atoms,
• or R denotes a hydrogen atom and R' denotes an aminoalkyl radical --(CH.sub.2).sub.v --NR.sub.10 R.sub.11 in which v is an integer from 1 to 3 and R.sub.10 and R.sub.11, which are identical or different, denote a hydrogen atom or a linear or branched alkyl radical containing from 1 to 3 carbon atoms, R.sub.10 and R.sub.11 being incapable of simultaneously denoting a hydrogen atom,
• or an organic salt or an inorganic salt of said at least one compound of formula (I).