what is different?

[lizardphunk]

I'm a curious chem newbie!

I have a simple question:

Say you've got 2-methyl-hexane and 3-methyl-hexane. Are these different alkanes? I think yes, but I'm not sure, since the formula is the same.

If I have 2-methyl-alkane and a 2-methylalkane that folds differently from the first one, are they different? (I don't know if this happens with simple

Comments

[lizardphunk]

http://www.lizardphunk.org/chem.jpg

I made a little drawing. I think the two would have different conformations?

I'm curios as to which would be more stable - my guess is the straight chain, but I don't have any clear ideas as to why. Because the folded one wants to be a ring, maybe?

[madlori]

All molecules have many conformational configurations, which is what you're talking about. But saturated alkanes have free rotation around all the bonds, so they'll naturally settle at the lowest-energy conformer, which is almost always the straight-chain conformer. They're not discrete compounds, so they don't have different reactivities. Alkenes, on the other hand, do NOT have free rotation around the double bond, which is why they have E and Z isomers.

[uberjason]

The ring-like chain would have steric interactions that the straight chain does not.

[lizardphunk]

Thank you both!