Question

How does one identify when to use "complex alkyl" rules for naming a molecule as opposed to using the general rules for naming alkanes?

Answer 1

The hydrocarbon IUPAC nomenclature is simple when the hydrocarbon is with a single longest straight chain and with simple simple unbrached substituents. But for higher alkanes containing more than one longest c chain with branched substituents. Let’s have an example,

Compound

1. Here 2 chains (A1 and A2) are of equal length. Then the “Complex Alkyl rule” The chain which will have substituent with least possible number is chosen as parent chain and other case is treated as substituent. Hence the A1 structure is chosen for further naming rules.
2. Then we can see the substituent on C4 of chosen A1 structure, which also branched and tied with main branch through particular C of its own. Then by “Complex Alkyl rule” the substituent also analyzed same way for numbering as for parent we did.
3. Then following “Complex Alkyl rule” the name given to hydrocarbon is,