Hyrdrocarbon naming question?

Question

When you're naming them, is there ever alternate ways to pick the 'longest' chain but still get to the same answer? Or is there always one way. I've seen a couple doing some online quizzes where I pick a different chain but still get the same answer.

Answer 1

You pick the longest chain, that has the first functional group alphabetically nearest to the first carbon.

C-C(Br)-C-C-C(Cl)-C that would be 2 bromo 5chloro -pent-whatver not a 2chloro-5bromo penta chemical.

The same thing goes with branches of carbons. If the chain can either have ethane or butane closer to the first carbon, you gotta use the butane.

Answer 2

You should always get the same answer when you follow all of the rules. There might be examples of symmetrical molecules where it seems that twochains are different chasins, but because of the symmetry you get the same correct result.