What is the pKa of formaldehyde? I know that after deprotonation, the lone pair will be left in an orbital orthogonal to the pi system, so it can't be resonance-stabilized

Chemistry Jan 27, 2021

What is the pKa of formaldehyde? I know that after deprotonation, the lone pair will be left in an orbital orthogonal to the pi system, so it can't be resonance-stabilized. However, the orbital is still an sp2 orbital, and there is some stabilizing effect from inductive withdrawal from the oxygen. I don't get why this proton's so hard to remove.