Arrange the following compounds in order of increasing dipole moment.

Toluene(I) m – dichlorobenzene(II)

O – dichlorobenzene(III) p – dichlorobenzene(IV)

(a) I

(d) IV

(c) IV

(d) IV

(b). Dipole moment of p – dichlorobenzene is zero because of symmetrical structure. o- and m-dichlorobenzene have higher dipole moments than toluene due to high electronegativity of chlorine than –CH₃ group. Further, to the o-dichlorobenzene has higher dipole moment due to lower bond angle than the m-isomer. Hence, the order of increasing dipole moment is :

P –dichlorobenzene (IV) < toluene (I)

< m –dichlorobenzene (II) < o –dichlorobenzene (III)

Dear Student,
Please find below the solution to your problem.

Dipole moment of p – dichlorobenzene is zero because of symmetrical structure. o- and m-dichlorobenzene have higher dipole moments than toluene due to high electronegativity of chlorine than –CH3 group. Further, to the o-dichlorobenzene has higher dipole moment due to lower bond angle than the m-isomer. Hence, the order of increasing dipole moment is :
P –dichlorobenzene (IV) < toluene (I)
< m –dichlorobenzene (II) < o –dichlorobenzene (III)

Thanks and Regards