1. CH3COH > 2. CH3COOCH3 > 3. CH3COCH3 > 4. CH3CH2OH.
This is because the more electronegative the substituents bonded to the carbon, the more they will withdraw electron density from the carbon-hydrogen bond, making the hydrogen more acidic.
In CH3COH, the oxygen atom is highly electronegative, and it withdraws electron density from the carbon-hydrogen bond, making the hydrogen more acidic. In CH3COOCH3, the oxygen atom in the ester group also withdraws electron density from the carbon-hydrogen bond, but to a lesser extent than in CH3COH. This is because the oxygen atom in the ester group is also bonded to a carbon atom, which donates electron density to the oxygen atom. In CH3COCH3, the methyl group is not as electronegative as the oxygen atom, so it does not withdraw electron density from the carbon-hydrogen bond as much. This makes the hydrogen in CH3COCH3 less acidic than the hydrogen in CH3COH and CH3COOCH3. In CH3CH2OH, the hydrogen atom is bonded to a carbon atom that is not bonded to any electronegative atoms. This makes the hydrogen in CH3CH2OH the least acidic of all four compounds.
