Boiling point of ethers and alkanes

[Queequeg]

My organic chemistry textbook says that ethers generally have higher boiling points than alkanes because of dipole-diole interactions, but why then does hexane have a higher boiling point than ethyl-propyl-ether? Is this principle then not true for larger alkanes with 5 or more carbons? Diethyl ether also has a higher boiling point than pentane, but then butane has a higher B.P than ethyl methyl ether.

 

[tdod]

2 reasons:

1) As an alkane or alkyl gets longer but does not branch, its BP increases b/c it can have more Van der Waals interactions; thus, ethyl-propyl-ether has a higher bp than ethyl methyl ether;;; hexane has a higher BP than pentance, etc. hope this helps.

 

[Borek]

My organic chemistry textbook says that ethers generally have higher boiling points than alkanes because of dipole-diole interactions

IMHO "generally" suggests it is just a rule of thumb, and as such can often fail.