???CO???NH2; and wherein Y is an oxygen atom or ???NR2; ii) 1 to 89 mol % of components of the general formula 4: wherein R3 is a hydrogen atom or an aliphatic hydrocarbon radical containing from 1 to 5 carbon atoms, p is 0 to 3, and R1 is hydrogen, an aliphatic hydrocarbon radical containing from 1 to 20 carbon atoms, a cycloaliphatic hydrocarbon radical containing 5 to 8 carbon atoms or an optio