Question

Rank the following isomers in order of increasing Doiling point.

Answer 1

More is the surface area of the occupied, more is its Boiling point.

If surface area of an alkene increases, then the boiling point of alkene increase. Boiling point decreases with increase in branching, which is attributed to the decrease in surface area.

Thus, among all the least boiling point is 2,3-dimethyl2-propene.

More is the Dipole moment, more is its boiling point. With increase in dipole moment, the interaction between molecules (Intermolecular forces) increases and thereby it is needed apply high temperature to reach its Boiling point.

In cis alkene, the two substituents are on the same side of a double bond. So, the cis alkene has a small net dipole.

In trans alkene, the two substituents are opposite to each other. So, the net dipole momentum become zero (i.e. no net dipole).

Therefore, cis alkene has higher boiling point than trans alkene.

Thus, the overall increasing order of boiling point is shown as follows: