[la_tiburtina]

Hi, I'm supposed to give the IUPAC name for this compound (see attached photo).

Naively I assumed I should start numbering from the "left-hand" side of the "hexane" because the closest first "branchpoint" would be the methyl group.

i.e., I want to name the compound 3-Bromo-2-Methyl-4-hexanol, but the book says it's 4-Bromo-5-methyl-3-hexanol.

What's the rule here that I'm missing?

Thanks!

[james_a]

Good start, you're almost there.
1. Identify parent chain.
2. Identify highest priority functional group (alcohol)
3. Number chain to give this the lowest number. So you want to make is a 3-alcohol vs. 4-alcohol.

So the rule you were missing was that when a functional group higher-priority than alkane is present, you number the chain to minimize the number of that functional group, not the alkane substituents.