Arrange the following alchohols and alkanes in increasing order of boiling point: 3-pentanol, n-pentane, 2,2-dimethylpropanol, n-pentanol

I understand that n-pentane would have the lowest boiling point because alkanes have a lesser BP than alcohols for the same number of carbons.

2,2-dimethylpropanol would be next because it has the most amount of branching and branching decreases BP as it makes the compound more compact (giving it the shape of a sphere).

But I am confused between n-pentanol and 3-pentanol, from intuition, 3-pentanol should have a lesser BP because it seems it will have more H-Bonding compared to n-pentanol and that is the right answer as well. But is that the actual reason? If not then what is the reason?

  • $\begingroup$ More or stronger hydrogen bonding usually increases BP. The purpose of the question is unclear; the differences among the many C-5 alcohols can be subtle. To see the main differences from shape and location look up the pentanes and the butyl alcohols; then graduate to the pentyl alcohols. $\endgroup$
    – jimchmst
    Commented Nov 2, 2023 at 16:48
  • $\begingroup$ As jimchmst said H bonding usually increases boiling point. All i could think of is, OH is like a "branch" in 3 pentanol which might be why its BP is less than n-pentanol $\endgroup$
    – daf
    Commented Nov 16, 2023 at 12:48


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