Rule 2 . In case of cycloalkanes, the word cyclo should be prefixed with the name of alkane. Thus, a cycloalkane containing three carbon atoms is called cyclopropane.
For substituted cyclohexanes, the name of the substituents is added as prefixes to the name of parent hydrocarbon.
Rule 3 . In case of branched alkanes, the longest carbon chain gives the name of the parent alkane. The substituents are to be prefixed using suitable locants. If there are multiple same substitutents, then the prefixes di-, tri, tetra - etc are added before the substituent name. Thus, the name of 1 is 2,3,7,8-tetramethylnonane.
If there are more than one type of substituents, then they are usually arranged in an alphabetical order. Thus, in compound 2 , ethyl group is mentioned before the methyl groups.
If more than one substituent is attached to the parent hydrocarbon, the chain is numbered in that direction that will result in the lowest number in the name of the compound (Rule of lowest locants).
Rule 4 . In case of bridged cycloalkanes, the naming is to be done in the following manner-
I. The number of rings is to be identified. The two rings in compounds 1 and 2 are depicted in different colours. The prefix bicyclo is to be added for these compounds.
II. The number of carbon atoms in each ring is to be counted including the carbons in the bridge but excluding those at bridge heads. Thus, in compound 1 , there are 2 carbons in both rings A and B while only 1 carbon in the bridge. Similarly, in compound 2 , there are 2 carbons in the ring A while 3 carbon atoms in the ring B but no carbons in bridge. This number of carbon atoms in each ring is written in a square bracket separated by a dot after the prefix bicycle in a descending order.
