Conjugate of oxoacid

[RachaelKoh3A]

In the stabilization of oxoacid conjugates (like CCl3COO- or CBr3COO-) in which there are electron withdrawing atoms such as halogens, does it matter if the halogen is less electronegative than the oxygen atom?

[Chem_Mod]

More electronegative atoms withdraw electrons more.

[Andrewwiner4D]

I know these are not the same acids but this is a good explanation Lavelle gave in 2014:
HOCl vs HOI --> To analyze the acidity of this pair you [censored] the polarizing power of the conjugate base (eg. -OCl and -OI). The more electronegative species (-OCl) will polarize ( pull charge towards it) the O-H bond. This withdraw away from the O-H bond weakens the bond (less electron density in the bond) and makes it easier to break. The O-H bond must be broken to form an acid hence it is stronger.

I talked about the halogen acids in discussion. As you go down the halogen column the elements get larger. Hence comparing the conjugate bases Cl- vs I- we see that I- is more stable because it is larger, which leads to I- being able to delocalize the negative charge over more volume leading to a lower energy state.


Let me know if this helped

[RachaelKoh3A]

Yes, thank you!