Rank the following compounds in order of increasing equilibrium constant for conversion to the hydrate.

Question

Quizplus · Accepted Answer

The equilibrium constant for conversion to the hydrate is dependent on the stability of the hydrate form. The stability of the hydrate increases with increasing electron density on the carbonyl carbon. Therefore, compound IV, which has a para-substituted electron-donating group, will have the highest stability and equilibrium constant. Compound II, which has an electron-withdrawing group, will have the lowest stability and equilibrium constant. Compounds I and III have similar electron density on the carbonyl carbon, but III has an additional stabilizing factor of intramolecular hydrogen bonding, making it more stable than I. Therefore, the correct order is IV < II < I < III.

Rank the Following Compounds in Order of Increasing Equilibrium Constant