Answers and Explanations

DISCRETE PRACTICE QUESTIONS

1 . A

Methyl  propanoate  is  an  ester;  it  can be  synthesized by  reacting    a   carboxylic  acid    with    an  alcohol

in  the presence    of  acid.   Here,   the parent  chain   is  propanoate, and the esterifying group   is  a

methyl  group.  Choice  (B) reverses    the nomenclature,   and would   form    propyl  methanoate. The

other   reactions   listed  would   not form    esters.

2 . D
This question asks for the products when ammonia reacts with acetic anhydride. Recall from the
chapter that an amide and a carboxylic acid will be formed. However, the carboxylic acid—an acid
—is in the same environment as ammonia—a base. The two will react, forming the ammonium
carboxylate shown.

3 . A
A Fischer esterification involves reacting a carboxylic acid and an alcohol with an acid catalyst.
Under these conditions, the carbonyl carbon is open to attack by the nucleophilic alcohol. The
rate of this reaction depends on the amount of steric hindrance around the carbonyl carbon
because there must be room for the alcohol to approach the carboxylic acid substrate. Choices
(B), (C), and (D) all have more crowding around the carbonyl carbon, which will decrease
reactivity. The additional alkyl groups in these other choices also donate electron density to the
carbonyl carbon, making it slightly less electrophilic.

4 . C
This question requires knowledge of the nomenclature of cyclic molecules. A δ-lactam, choice
(A), has a bond between the nitrogen and the fourth carbon away from the carbonyl carbon. This
ring will have six elements: the nitrogen, the carbonyl carbon, and the four carbons in between.
Cyclohexane carboxylic acid, choice (B), has cyclohexane, a six-membered cycloalkane. The
anhydride formed from pentanedioic acid, choice (D), will have the five carbons in the parent