Explain the longest chain rule and the smallest number for functional groups rule of Nomenclature by the IUPAC system - with suitable examples.
IUPAC Nomenclature of Branched/Complex Alkanes
(1) Select the longest chain of carbon atoms in the molecule. Count the number of carbon atoms in that chain and name according to the following rules. When chains of equal lengths are competing for selection, that chain is selected which has more number of substituents.
(2) Carbon atoms in the longest chain selected as above in numbered consecutively form one end to the other such that the substituents attached get the lowest number.
(3) Each substituent, which obviously, is an alkyl group is named according to a number of carbon atoms present in it and it is prefixed by the number to which it is located in the main chain.If the same substituent occurs more than once in the molecule, the prefix di (for two), tri (for three), etc. used to indicate how many times it appears.The name of the compound is composed in such a manner that each substituent with its number and name is written alphabetically just before the parent name. Prefixes di, tri, tetra etc. are not considered in deciding alphabetical order.
IUPAC Nomenclature of Branched/Complex Alkanes
(1) Select the longest chain of carbon atoms in the molecule. Count the number of carbon atoms in that chain and name according to the following rules. When chains of equal lengths are competing for selection, that chain is selected which has more number of substituents.
(2) Carbon atoms in the longest chain selected as above in numbered consecutively form one end to the other such that the substituents attached get the lowest number.
(3) Each substituent, which obviously, is an alkyl group is named according to a number of carbon atoms present in it and it is prefixed by the number to which it is located in the main chain.If the same substituent occurs more than once in the molecule, the prefix di (for two), tri (for three), etc. used to indicate how many times it appears.The name of the compound is composed in such a manner that each substituent with its number and name is written alphabetically just before the parent name. Prefixes di, tri, tetra etc. are not considered in deciding alphabetical order.
