Factors that determine acid strength

Jul 23, 2021

chemJan2021

Homework Statement: In these two compounds, the question is to decide more acidic hydrogen.

In No.1, I think the right hydrogen is more acidic because halogen (Fluorine) connects the oxygen next to the hydrogen, pulls the electron and this inductive effect makes the hydrogen more stable.
But the answer is the left hydrogen.
I can’t understand this answer.

In No.2, I also think right hydrogen is more acidic because there is a methyl group on the left side of carbon which is electron donating group and makes the left hydrogen unstable.
But the answer is the left hydrogen.
I think there are the mesomeric effect on both of the hydrogens.
I can’t understand the answer.
Could anyone explain me the reason?

Relevant Equations: I think to solve this kind of more acidic hydrogen, there are these rules below.
1. Compare the element to which a hydrogen bonds.
2. Check if there is the Resonance effect.
3. Check if there is the Inductive effect.
4. The percentage of the S orbitals. SP>SP2>SP3

Jul 23, 2021

docnet

Gold Member

Both molecules require drawing resonance structures of the conjugate bases to see where the electrons become delocalized.

5. How does bond strength affect acid strength?

The weaker the bond between the hydrogen atom and the rest of the molecule, the easier it is for the hydrogen atom to be separated and donated as a proton, making the acid stronger. This is because a weaker bond means less energy is required to break the bond and donate the proton.