Give an example for each of the following:

a. a β-keto nitrile

Give an example for each of the following:

b. a β-diester

Give an example for each of the following:

c. a β-keto aldehyde

Explain why a base can remove a proton from the α-carbon of N,N-dimethylethanamide but not from the α-carbon of either N-methylethanamide or ethanamide.

Explain why the $\alpha$-hydrogen of an N,N-disubstituted amide is less acidic (pK_a = 30) than the $\alpha$-hydrogen of an ester (pK_a = 25).

Rank the compounds in each of the following groups from strongest acid to weakest acid:

a.

Rank the compounds in each of the following groups from strongest acid to weakest acid:

c.

Explain why 92% of 2,4-pentanedione exists as the enol tautomer in hexane but only 15% of this compound exists as the enol tautomer in water.

Draw the enol tautomers for each of the following compounds. For compounds that have more than one enol tautomer, indicate the one that is more stable.

d.

e.

Draw the enol tautomers for each of the following compounds. For compounds that have more than one enol tautomer, indicate the one that is more stable.

f.

A ketone undergoes acid-catalyzed bromination, acid-catalyzed chlorination, racemization, and acid-catalyzed deuterium exchange at the ⍺-carbon. All of these reactions have similar rate constants.What does this tell you about the mechanisms of these reactions?