Hex-2-ene is represented as:
Geometrical isomers of hex-2-ene are:
The dipole moment of cis-compound is a sum of the dipole moments of C–CH3 and C– CH2CH3 bonds acting in the same direction. The dipole moment of trans-compound is the resultant of the dipole moments of C–CH3 and C–CH2CH3 bonds acting in opposite directions. Hence, cis-isomer is more polar than trans-isomer. The higher the polarity, the greater is the intermolecular dipole-dipole interaction and the higher will be the boiling point. Hence, cis-isomer will have a higher boiling point than trans-isomer.