How do the boiling points of comparable alkanes, alkenes and alkynes vary? Been searching for like 10 minutes, no luck here. Seems like it varies on a case by case basis...please do explain the concept behind it as well, thanks.
I kinda thought so, but after looking for 2 hours on the net, no good answers, so I graphed alkane vs terminal alkene and other stuff.. (looked up the freaking BP manually...grrr....) and these are the conclusions...When comparing alkynes, alkenes, and alkanes of similar molecular weight and structure(unbranched), I am pretty sure alkynes will have the highest boiling point due to the fact of increased electron density from your pi orbitals. It is more "polarizable" so you have an increased dipole-dipole interaction between molecules thus increasing bp. I think that sounds right, what do you think?
Yeah, close call indeed, half the damn time there was only like a 1 or .5 degree difference in BP, but I guess there is.....it would be really close to call. there isnt much of a diff. all i can think of is to add to post #2 and that cuz the alkyne is planar it will have higher dipole dipole interaction. although the alkene is planar its dipole wont be as strong as that of the alkyne. that would be my reasoning, i could be wrong.