We have discussed how alkoxide anions are less stable than similarly sized carboxylate anions. Did you know that alkoxide is even less stable than hydroxide? Alcohols are weaker acids than water.

The alkoxide anion is less stable than hydroxide both because of the weakly electron donating nature of aliphatic groups (pushing negative charge onto negative charge increases energy) and the reduced access to the anion by solvating water molecules because of the aliphatic portion of the molecule.