"In haloalkanes, the large electronegativity difference between halogen and carbon atoms means that the carbon-halogen bond is polar. This makes the bond weaker than one without a dipole" - excerpt from my textbook

I don't particularly understand the last sentence. Can someone elaborate and explain what does "this makes the bond weaker than one without a dipole" means?

the strength of the inter molecular force goes the following: Dispersion, Dipole–Dipole and Hydrogen Bonding.

From my interpretation: Without dipole is equivalent to dispersion and dispersion is subsequently weaker than dipole dipole. But why does dipole dipole weaker than one without a dipole? Shouldn't it be stronger?

That sentence continues with "Species such as another halogen ion, a cyanide ion, ammonia can be substituted for the halogen in the polar bond."

Any help will be great. Thanks.

  • 4
    $\begingroup$ Polar bond is not weak, but can easily be breakdown in polar and ionic solvents due to electrostatic interaction. In such solvent the negative and positive part of the solvent attracts the positive and negative part of the haloalkanes, thus facilitates the bond breaking of haloalkanes. $\endgroup$
    – Manu
    Jul 15 '20 at 14:13
  • $\begingroup$ Please provide a reference to the textbook you are citing. $\endgroup$
    – andselisk
    Jul 15 '20 at 16:31
  • $\begingroup$ @Manu I am a novice. So in a polar solvent, C-F bond is the weakest (highest electronegativity difference, hence the highest electrostatic attraction). In a non-polar solvent, C-I bond is the weakest (longest bond length, hence strongest bond strength)? Thank you! $\endgroup$
    – 234ff
    Jul 16 '20 at 12:45
  • $\begingroup$ Yes, due to high electrostatic interaction with the polar solvent component. $\endgroup$
    – Manu
    Jul 16 '20 at 15:27

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