[Nestwr]

Greetings from Europe! I would like to ask about the boiling point between propane, propene and propyne.

Considering the molecular mass criteria someone would say the right boiling point sequence is Propane > Propene > Propyne . Wrong.

Considering the covalent bonds presence another one would say that Propyne > Propene > Propane is the right answer. Close but still wrong.

Can someone explain me why the right order in terms of boiling point is Propyne > Propane > Propene ?

[rolnor]

I think the interaction between molecules can be so complex that simple rules are difficult, its depending on factors such as geometry besides dipole interactions etc. and this is hard to predict.

[Nestwr]

Thank you Rolnor but i am optimistic. I believe there has to be a clear explanation out there and someone will help me to figure out.

[rolnor]

There is a explanation but you can probably not use this for any hydrocarbon.

[Corribus]

Think molecular shape and probably also pi-pi interactions.