Which compound has the highest dipole moment among the given options?

To determine the compound with the highest dipole moment among the given options, we need to consider the polarity of each compound. The dipole moment is a measure of the separation of positive and negative charges within a molecule. It is influenced by the electronegativity difference between the atoms in a molecule and the molecular geometry.

Let's analyze each compound and their dipole moments:

a) O-chloro Toluene:
Toluene is a nonpolar molecule since the electronegativity difference between carbon and hydrogen is very small. The addition of an O-chloro group does not significantly change the polarity of the molecule. Therefore, the dipole moment of O-chloro Toluene is relatively low.

b) M-chloro Toluene:
Similar to O-chloro Toluene, M-chloro Toluene is also a nonpolar molecule due to the small electronegativity difference between carbon and hydrogen. The position of the chlorine atom in the middle of the molecule does not enhance its polarity. Hence, the dipole moment of M-chloro Toluene is also low.

c) P-chloro Toluene:
In P-chloro Toluene, the chlorine atom is located at the para position relative to the methyl group. This position creates a significant dipole moment due to the electron-withdrawing effect of the chlorine atom. The chlorine atom is more electronegative than carbon and hydrogen, resulting in a partial negative charge on the chlorine and a partial positive charge on the carbon. The dipole moment of P-chloro Toluene is relatively high compared to the other compounds.

d) P-dichloro Benzene:
In P-dichloro Benzene, there are two chlorine atoms located at the para positions relative to each other. This arrangement creates a stronger dipole moment compared to P-chloro Toluene since there are two electron-withdrawing chlorine atoms. However, the overall dipole moment of P-dichloro Benzene is lower than that of P-chloro Toluene due to the cancellation of dipole moments caused by the symmetry of the molecule.

Therefore, the compound with the highest dipole moment among the given options is P-chloro Toluene (option c).