[toadesque]

I have this:



The answer is: 2-Methyl-5-(1-methylethyl)octane

I'm confused as to where the 1-methylethyl is coming from. I understand that there are 2 carbons there so it is ethyl but why is it 1-methyl?

[macman104]

Because the group in the box has an ethyl group as it's longest chain.  But there are 3 carbons, and the third carbon hangs off of the 1 position of that side chain, making it 1-methyl, so 1-methylethyl

[Vidya]

You have to go through the rules of complex IUPAC nomenclature .
Complex chain is also numbered in the same manner and carbon attached to main chain is always numbered as 1.Rest of the naming follows the same rule.So now you have methyl on the first carbon and side chain is of length of two carbons so name is 1-methylethyl

[Fridushka]

I have a question related to this..
which is better to write, 1methylethyl or isopropyl?

[Vidya]

isopropyl is more widely used .

[Fridushka]

thx for the reply:)

[cms2002]

isopropyl is more widely used .

Just a word of caution, "isopropyl" is common usage and not technically IUPAC (according to my professor who docked points for using "isopropyl" and not "methylethyl" on an IUPAC exam question).

Hope that helps.