The parent chain must contain the multiple bond regardless of the fact whether it also denotes the longest continuous chain of carbon atoms or not. 2 If both double and triple bonds are present, the numbering of the parent chain should always be done from that end which is nearer to the double bond or triple bond , i.e. the lowest set of locant rule for the multiple … [Read more...] about Rules For IUPAC Nomenclature Of Unsaturated Hydrocarbons