Arrange the following compounds in order of increasing dipole moment. Toluene (I) m-dichlorobenzene (II) o-dichlorobenzene (III) p-dichlorobenzene (IV)(a) I < IV < II < III (b) IV < I < II < III(c) IV < I < III < II (d) IV < II < I < III
Answers
Answer:
(b) IV < I < II < III is the correct answer.
Explanation:
Toluene is ans aromatic hydrocarbon.
It is also called as tuloul.
It is a mono (single) substituted benzene.
It consists of CH3 group attached to the phenyl ring.
All electrons of benzene are shared equally among carbon.
So it has no net dipole moment.
m dicholoro benzene
It has formula C6H4Cl2.
It is basically 1,3 dichloro benzene.
The dipole moment of m dichloro benzene is high.
It is due to it's symmetrical structure.
o-dichlorobenzene
It has formula C6H4Cl2.
It is basically 1,2 dichloro benzene.
It has higher dipole moment.
It is because elctronegativity of Cl group is greater than that of CH3 group.
It has lower bond angle than m dicholoro benzene.
p- dicholoro benzene.
It has formula C6H4Cl2.
It is basically 1,4 dichloro benzene.
It has zero dipole moment.
It is because of symmetrical structure.
Thus the correct answer is (b) IV < I < II < III
Answer:
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)
Explanation: