Question

Choose the correct statement(s) related to the conformers of ethylene gylcol (about $C-C$ bond).

• A. Dipole moment of anti form is zero
• B. Dipole moment of anti form is non-zero
• C. Dipole moment of gauche form is zero
• D. Dipole moment of gauche form is non-zero

Answer 1

Answer: (B), (D)

Dipole moment of gauche form is non-zero

In general, dipole moment of anti conformers are zero because the similar group will be in opposite direction so their value will cancel each other.

In gauche conformer of gylcol, the OH group will be in similar direction so their magnitude of dipole moment will add up and the resultant dipole moment will be a non-zero integer. Thus, dipole moment of gauche conformer of gylcol is non-zero.

In anti conformer of gylcol, the OH group present in the opposite direction (anti-periplanar) so their dipole moment can cancel each other to give zero dipole moment. But here, this is not the case. The lone pair of electrons on oxygen plays a vital role.

The lone pair on both oxygen are not in opposite direction so they won't cancel each other. Hence, the resultant dipole moment will be a non-zero integer.