How do you figure out the positional and chain isomer possibilities of a compound?

Question

I need to figure out the chain and positional isomers of C4H7Cl. I am not looking for someone to directly give me the answer, I just want to know what steps are needed to be able to figure them out for a given compound.

This is different to my prior question. Here I am asking for the technique, not the direct answer. Thanks.

Possible duplicate of What are some examples of chain and positional isomers of C4H7Cl? — Mithoron, Jan 29 '16 at 22:13
You should have edited your old question, don't ask second time about the same topic. — Mithoron, Jan 29 '16 at 22:18
Would it have reappeared on the main question page if I edited it? — Tom, Jan 29 '16 at 22:19
It would need to be reopened before answer could be posted - editing would need to validate opening. — Mithoron, Jan 29 '16 at 22:23
http://chemistry.stackexchange.com/questions/7452/constitutional-isomers-of-cis-1-2-dibromocyclopentane — Mithoron, Jan 29 '16 at 22:26

score 2 · Answer 1 · answered Jan 29 '16 at 22:43

Is the parent hydrocarbon unbranched? That would be n-butane, $\ce{C4H10}$. Replacing one hydrogen atom by chlorine would lead to $\ce{C4H9Cl}$. Apparently, you're not having that!
Move a methyl group in n-butane, yielding 2-methylpropane, $\ce{C4H9}$. Here, replacing one hydrogen atom by chlorine gives $\ce{C4H8Cl}$. You're not having that either!
Does your target molecule have $\ce{C=C} $double bonds? Calculate the number of double bond equivalents in $\ce{C4H7Cl}$! I count one.

Work your way down from here.

How do you figure out the positional and chain isomer possibilities of a compound?

1 Answers1