If the equilibrium constant (Khydr) for the hydration of acetone is 2×103, would you expect the Khydr of hexafluoroacetone to be smaller or larger than that of acetone?
Response:
This question can easily be solved by first drawing out the line-angle notation for both acetone and hexafluoroacetone. You should have the general nomenclature for aldehydes and ketones memorized for situations where condensed formulas are not given.
Both compounds contain a carbonyl carbon which is partially positive because of electron density being drawn to the more electronegative oxygen. Also note the slight difference in the two compounds. Acetone has two methyl (-CH3) groups, while hexafluoroacetone has two trifluoromethyl (-CF3) groups. Think about these differences.
Refer to your notes regarding hydration of ketones/aldehydes without an acid/base catalyst. Think about how the substituent groups affect this characteristic.
Using this information, would you expect the Khydr of hexafluoroacetone to be smaller or larger than that of acetone?