Why do haloalkanes have a higher boiling point than alkanes?

Answer 1

cycloalkanes have a higher boiling point than alkanes because there are more points of contact between the carbon-carbon chain, and thus more intermolecular Van Der Waal (or London) forces.

Similarly, the boiling point of alkanes increases as the length of the carbon chain increases. This is because more intermolecular forces are present, hence more energy in heat form is required to break the bonds. Branching in the alkanes reduces the boiling point as it reduces the points of contact.

Answer 2

There are a number of factors ( I am assuming the comparison is between CnH2n+2 and CnH2n+1X (X= halogen)

• haloalkanes are polar- and there will be dipole-dipole interactions not present in the non-polar alkanes
• haloalkanes have many more electrons than the corresponding alkane- so the london dispersion forces will be greater
• haloalkanes are heavier than their corresponding alkane (very minor effect)

Answer 3

Haloalkanes have higher boiling points than alkanes because the electronegative halogen atoms can form dipole-dipole interactions with neighboring molecules, increasing the intermolecular forces. This results in a higher energy requirement to overcome these forces and change the haloalkane from a liquid to a gas.