Why are solid alkyl halides insoluble in water?
The majority of the molecule is non-polar.
Alkyl halides are basically aliphatic carbon chains with a halogen atom or atoms bonded to them.
The halogen atom is electronegative, so it will have some polarising effect on the molecule, however, unless the molecule is very small, most of it will consist of aliphatic carbon chain, which is non-polar.
If you take a small molecule such as chloroform (
By the time we move to the n-butyl chloride (
For an alkyl halide to be solid, you would expect the alkyl chain to be very long - even the C10 derivative 1-chlorodecane is liquid at room temperature. It means that the molecules will have very long chains of carbon-carbon bonds, which are non polar and insoluble in water.