1-propanol boils at 97°C, while 2 propanol boils at 87.5°C. What would account for this difference in boiling point?

1 Answer
Apr 17, 2018

Both have H-bonding, but 1-propanol has better London Dispersion forces. See Below.


Both molecules have H-bonding, so we don't really have to worry about that.

I think of london dispersion forces as like making total contact. Assuming masses are the same, the thing that can make more contact will have greater london dispersion forces.

1-propanol is a 3 carbon chain that can "lay" on top of another 1-propanol pretty easily.

2-propanol is a 3 carbon chain with the OH group sticking up in the middle of the chain. So this chain has a harder time to "lay" on top of one another. In this chain, the amount of London contacts is reduced, and so the boiling point is reduced.