nomenclature confirming plz

[Ice-cream]

hey can anyone confirm whether i've got the name of this organic compound right?

 

CH3CH(Br)CH(CH3)CH2CH(phenyl)CH2CH3

 

is it 2-bromo-3-methyl-5-phenylheptane? (or is it 6-bromo-5-methyl-3-phenylheptane?)

[dan19_83]

as far as i can see, both are correct.

 

it's just a matter of which one you want to call C1, it can be the first or the last one, either way you will still end up with two compounds that have the same structure.

[Dak]

the carbons are numbered from the end of the chain which is nearest to the most significant functional group.

 

so, if the bromine has the most impact on the chemistry of the molecule, C-1 will be to the left. if phoenol is the most important group there, C-1 will be to the right.

 

eg,

 

CH₃CH₂CH₂CHOHCH₃

 

is pentan-2-ol, whereas

 

CH₃C=OCH₂CHOHCH₃

 

is 2-keto-pentan-4-ol. the -OH is in the same position in both, but the presense of the =O group in the second molecule flips the order in which the carbons are numbered, as ketone groups are more active than alcohol groups.

 

oh, and i beleve a 6-carbon alkane is called hexane; i think heptane is 7 carbons (though my memory is a bit fuzzy on this)

[andy_rodger5]

The molecule could be named either way, as Dak says depending upon which of the functional groups has the most impact on the chemistry of the molecule.

 

There are, however, 7 carbons in the chain. So both of your names could be correct, you will just have to find out which of the functional groups has more impact on the chemistry.

 

I would have said it is more likely to be the halogen group (Bromo-), but research is required...