Composition of lipoamino acids and alkanediols, process for the preparation thereof, and cosmetic or pharmaceutical composition resulting therefrom

A composition (C1) comprising, per 100% of mass:

• (a) —a mass proportion of greater than or equal to 50% by mass and less than or equal to 95% by mass of a compound of formula (I) or of a mixture of compounds of formula (I):
• X—[CH2]p—C(═O)—Y—OH (I),
• in which p represents an integer greater than or equal to 10 and less than or equal to 20, Y represents either a divalent radical of formula (IIa):
• —[N(R3)—CH(R2)—C(═O)—]m— (IIa),
• in which R3 represents a hydrogen atom or a methyl radical, m represents an integer greater than or equal to 1 and less than or equal to 4 and R2 represents a hydrogen atom or a radical chosen from methyl, isopropyl, isobutyl, 1-methylpropyl, benzyl and 3-aminopropyl radicals;
• or a divalent radical of formula (IIb):
• in which R4 represents a hydrogen atom or a hydroxyl radical and n represents an integer greater than or equal to 1 and less than or equal to 4;
• and X represents either a methyl radical or a monovalent radical of formula (III):
• HO—Y′—C(═O)— (III),
• in which Y′ represents either the divalent radical of formula (IIa) as defined previously, or the divalent radical of formula (IIb) as defined previously, wherein when X represents the radical of formula (III), Y and Y′ are identical;
• (b) —a mass proportion of greater than 0% by mass and less than or equal to 25% by mass of a linear or branched alkanediol containing from six to eight carbon atoms;
• (c) —a mass proportion of greater than or equal to 0% by mass and less than or equal to 5% by mass of a compound of formula (V) or of a mixture of compounds of formula (V):
• X—[CH2]p—C(═O)—OH (V),
• in which X represents a methyl radical, p represents an integer greater than or equal to 10 and less than or equal to 20, or a mixture of said compounds of formula (V);
• and
• (d) —a mass proportion greater than 0% by mass and less than or equal to 50% by mass of water,
• it being understood that the pH of said composition is less than or equal to 3.