Haloalkanes and Haloarenes – Solutions

1) Which one of the following has the highest dipole moment?

i) CH₂Cl₂

ii) CHCl₃

iii) CCl₄

Solution

ii) CHCl₃

Tetrachloromethane (CCl₄) is a symmetrical molecule and has zero dipole moment.

In chloroform (CHCl₃), the resultant dipole moment of two C-Cl bonds is cancelled by resultant dipole moment of C-Cl and C-H bonds. Therefore, the resultant dipole moment (m= 1.03 D ) is smaller.

In dichloromethane (CH₂Cl₂) , the resultant dipole moments of two C-Cl and two C-H bonds reinforce one another .