Use of polycarboxylic acid compounds for the treatment of fibrious amino acid based substrates, especially hair

A compound (B)

• which is selected from the group consisting of:
• a compound of the formula:
• wherein R5 is selected from the group consisting of hydroxy and F, wherein F is
• F is selected from:
• —O—C(O)—R3—C(O)OH, and
• —NR1—C(O)—R3—C(O)OH,
• where R3 is selected from a single bond or optionally substituted straight-chain, cyclic, branched, saturated, unsaturated, and aromatic hydrocarbon radicals which have up to 100 carbon atoms, which optionally contain one or more groups selected from —O—, —NH—, —C(O)—, —C(S)—, tertiary amino groups
• and quaternary ammonium groups
• with the proviso that R3 is not —CH═CH—,
• with the proviso that at least two of R5 are F;
• a compound of the formula:
• wherein one of R9 is hydroxy and one of R9 is a group of the formula
• and wherein F is as defined above and the dotted line is the bond to the carbon atom;
• a mixture of the following two isomers:
• wherein F is as defined above;
• and,
• a compound of the formula:
• wherein x is from 1 to 10, and F is as defined above.