R1N(R5)C(O)R2C(O)L or R1C(O)N(R5)R2C(O)L and mixtures thereof; wherein R1 is an alkyl group containing from about 6 to about 12 carbon atoms, R2 is an alkylene containing from 1 to about 6 carbon atoms, R5 is H or alkyl, aryl, or alkaryl containing from about 1 to about 10 carbon atoms, and L is a suitable leaving group.