Question: How to arrange the molecules in increasing order of Bronsted acidity?
I know that mineral acid will have the greatest acidity, thus VI is most acidic.
This is followed by carboxylic acids, I and II. II has an electron donating group, which makes it less stable than I.
So I know the ranking will be
X,X,X,II,I,VI.
However, between III, IV and V, I have trouble determining the acidity between them.
IV will be anti-aromatic when it loses H+, which makes it really unstable (hence weak acid).
Not very sure about esters, but the only way it can be an acid is to donate H+ from the Me group.
For alkynes, I know it's rather acidic too (compared to alkanes and alkenes at least).
My guess would be that the ranking is IV,III,V,II,I,VI.
Any thoughts?