So I've learned that HCl is a stronger acid than HF because Cl is able to better stabilize the negative charge better than F while in its anionic form. So why is it that CF3OH is a stronger acid than CCl3OH? I thought that when it came to elements in the same column, size dictated acid strength? Is it because in the conjugate base CF3O- the charge is on the Oxygen atom, so it has nothing to do with anion size and all to do with electronegativicity (not sure if real word lol).
Question about acidity in organic compounds
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In both CCl3OH and CF3OH, the proton is lost off of the oxygen, not either of the halogens.
Because the atom carrying the charge is oxygen in both conjugate bases, size of the conjugate anion is equal. The only difference is in what the anion is bonded to in each case. There is no resonance possible in either the CCl3O- or CF3O- molecules, but the inductive effect of the halogen substituents draws on the electronic field of the oxygen in each case. Because fluorine is more electronegative than chlorine, the inductive effect weakens the O-H bond in CF3OH more than in CCl3OH, making the fluorinated compound more acidic.
Because the atom carrying the charge is oxygen in both conjugate bases, size of the conjugate anion is equal. The only difference is in what the anion is bonded to in each case. There is no resonance possible in either the CCl3O- or CF3O- molecules, but the inductive effect of the halogen substituents draws on the electronic field of the oxygen in each case. Because fluorine is more electronegative than chlorine, the inductive effect weakens the O-H bond in CF3OH more than in CCl3OH, making the fluorinated compound more acidic.
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