Question

Why is solubility of haloalkanes in water is very how although they are polar in nature.

Answer 1

A compound consisting of alkanes attached with one or more halogens is known as halo alkanes. Halo alkanes dissolves in organic solvents but solubility in water is pretty low. Solubility depends upon the intermolecular forces of attraction.

Complete step by step answer:
Halo alkanes are polar compounds. Water is also a polar compound. According to “like dissolves like” properly, halo alkanes should dissolve in water. But, the solubility of haloalkanes show a difference, they have low solubility in water. The reason for the same lies in the energy and intermolecular attractions.
For dissolving haloalkanes in water, we first need to break bonds between halo alkane molecules held together by Vander waals forces and dipole – dipole interactions. The hydrogen bonds of water also need to be broken. Both these bond breakages require a high amount of energy. But, when bonds between haloalkanes and water molecules are formed, it leads to release of energy. The released energy is lower than the energy required to break the bond. Therefore, that energy cannot be overcome by newly formed dispersion forces and dipole – dipole bond between haloalkanes and water. Hence, the solubility of haloalkanes for energetics and thus, they are having low solubility in water.
Additional information: Haloalkanes are of three types i.e. primary, secondary and tertiary. Haloalkanes, in which the carbon having halogens attached on it is linked to one alkyl group only are primary haloalkanes and in which the carbon having halogens attached on it is linked to two alkyl groups are secondary haloalkanes. Tertiary haloalkanes are the haloalkanes in which the carbon atom having halogen is directly attached with three alkyl groups.

Note:
When haloalkanes are dissolved in organic solvent, the energy of bond breakage and the released energy after interaction of haloalkanes with organic solvent is almost the same. Therefore, they dissolve pretty high in organic solvents such as benzene.