Tocopheryl radical is understood as meaning the radical of formula (II) below: ##STR4## in which R1, R2 and R3 independently are a hydrogen atom or a methyl radical and A is the group ##STR5## when RO is an oxyethylenated chain, n will generally be greater than or equal to 1, for example between 2 and 50, preferably between 2 and 25 and in particular equal to 2 or 5.