Boiling points

Eau

15

Why does proponone (56ºC) have a higher b.p. than propanal(49ºC)?

Thanks in advance.

Reply 1

nota bene

15

The propanone is more symmetric than propanal (has its O located in the middle of the molecule instead of at the end), which means it is harder to tear apart than the less symmetric molecule...

This is how I think, but I am not sure if it is right...

nota bene

The propanone is more symmetric than propanal (has its O located in the middle of the molecule instead of at the end), which means it is harder to tear apart than the less symmetric molecule...

This is how I think, but I am not sure if it is right...

I'm afraid you think almost completely wrong...
Intramolecular bonds (i.e. normal covalent bonds) are NEVER broken when a substance boils unless it decomposes at the same time.

The question is about intermolecular forces.

The intermolecular forces are greater in propanone than propanal. This can only be because the dipole-dipole interactions in propanal are weaker than in propanone, although this initially seems counter-intuitive as the dipole on the CO in propanone is weaker than the dipole on propanal.

Reply 3

nota bene

15

charco

I'm afraid you think almost completely wrong...
Intramolecular bonds (i.e. normal covalent bonds) are NEVER broken when a substance boils unless it decomposes at the same time.