[specialk08]

Ok, so I have a question that says explain why cis-1,3-dichlorocyclohexane is LESS stable than cis-1,2-dichlorocyclohexane using one sentence.

But when I draw these two structures, I get the 1,2 isomer to have 2 chloros to be in equatorial and axial position, where as 1,3 isomers are both in equatorial position....why then wouldn't 1,3 be more stable ?

[maivu]

Chlorine is more electronegative than Carbon. In C-Cl bond, Cl tends to drag bonding electrons toward itself to generate dipole-dipole moment.

In cis-1,2-chlorocyclohexane, chlorine is on one side of the cyclohexane and dipole-dipole moment is much stronger than that in cis-1,3-chlorohexane.

Additionally, in cis-1,3-chlorohexane, Cl is put in 1, 3 position. The dipole-dipole moment is scattered.

[voidSetup]

The 1,2 isomer has one chlorine in the equatorial position and one in the axial position. This isomer can undergo chair flipping.  The 1,3 isomer has both substituents in the equatorial position and is prevented from chair flipping due to steric hindrance (1,3 diaxial interactions).

[specialk08]

Thanks guys!!