Nomenclature of Alkanes
Nomenclature of Alkanes:
Following are the rules for giving names to alkanes;
Parent Chain Selection:
First, select the longest carbon chain and considered it as a parent chain.
If there are two longest chains of the same carbon number are possible then consider that chain that contains more branching points or more substituents.
Substituents:
All parts of the molecule other than the parent chain are considered substituents.
Numbering of parent Chain:
Number the chain from that side which results in lower numbers of substituents.
If numbering is possible from both sides, then the number from that side results in lower numbering to the next substituent or second branch point.
Numbering and naming substituent:
Substituents are numbered by the number of the carbon atom to which they are attached. If the same substituent is present more than once then prefixes di for two, tri for three, tetra for four, penta for five, and so on are used with the name of the substituent.
Writing name of compound:
The name is written as one word. Substituents are named first and parent is named last.
A Hyphen (-) is used to separate prefixes and commas are used between the numbers.
Substituent names are written alphabetically. Prefixes are not considered while writing substituents alphabetically.
Naming with complex substituent:
If the substituent complex i.e., contains 4 or more carbons it is named by considering it as a separate parent molecule and numbered it from the carbon which is attached to the main parent chain. The numbering goes on to a larger chain and is named as explained in previous steps.
This compound is named 2-methyl-5(1-methyl propyl)nonane
Examples:
