What are possible isomers of bromopentane?

Answer 1

There are numerous possible constitutional isomers of bromopentane. Specifically, the bromine atom can be attached to any of the carbon atoms (although there are only three unique possibilities because the 2 end carbons are identical). So you could have:

• 1-bromopentane (same molecule as 5-bromopentane, but lower number is used)
• 2-bromopentane (same molecule as 4-bromopentane, but lower number is used)
• 3-bromopentane

Then you can also have different connectivity between the carbon atoms. So pentane can either be normal pentane (5 carbons in a row), or it can be a branched structure. There are two possible branched structures for pentane: 2-methylbutane ("isopentane") and 2,2-dimethylpropane ("neopentane").

For 2-methylbutane the possibilities are:

• 1-bromo-2-methylbutane
• 2-bromo-2-methylbutane
• 2-bromo-3-methylbutane (bromine takes precedence and gets the lower number)
• 1-bromo-3-methylbutane

Finally, there's only one possibility for 2,2-dimethylpropane, since the four methyl groups are equivalent and the central carbon is already bonded to four other things:

• 1-bromo-2,2-dimethylpropane