(1) Parent chain : Select the longest possible chain of carbon atoms containing the functional group and the maximum number of multiple bonds as the parent chain without caring whether it also denotes the longest possible carbon chain or not. (2) Lowest locant rule for the functional group: Number the parent chain in such a way that the functional group gets the … [Read more...] about Rules For IUPAC Nomenclature Of Compounds Containing Functional group, Multiple Bond And Substituents