For a compound with molecular formula C4H9Cl – 3 isomers (1°, 2°, 3°) arc possible. Among the isomeric alkyl halides, the boiling point decreases with the increase in branching in the alkyl chain. This is because with increase in branching, the molecule attains spherical shape with less surface area. As a result, the intermolecular forces become weak, resulting in lower boiling point. Therefore the boiling point decreases in the order:
Hence, (CH3)3 C-Cl has the lowest boiling point.
