Question

Why melting point of trans is greater than cis ?

Answer 1

The melting point of trans isomers is generally higher than that of cis isomers because in trans isomer, bulky groups lie on the opposite side of the double bond. Therefore, the molecule is symmetrical and hence packed well in the crystal lattice. On the other hand in the cis isomer, the bulky groups are present on the same side of the double bond. Hence, the cis isomer is unsymmetrical and its molecules are not packed well in crystal lattice. So, the intermolecular forces of attraction in the trans isomer are stronger than in the cis isomer, because of which the melting point of trans isomer is more than that of cis isomer.