Compare the boiling temperatures and the solubilities of the following substances:
Dimethylether, ethanol and ethanal
$t_{b}$(ethanol)= $78^oC$
> $t_{b}$(ethanal) = $ 20^o C$
> $t_{b}$(dimethylether) =$-20^oC$
Solubility(ethanol)
> Solubility(ethanal)
> Solubility(dimethylether)
Explanation:
1) The strength of van der Waals forces are almost identical between the hydrocarbon chains.
2) Ethanol has many intermolecular hydrogen bonds, acetaldehyde still has a strong polarity due to its carboxyl group, dimethylether has a very low polarity because the dipoles are canceled partly by symmetry:
