General Review
22-1
Possible set of reactants:

22-2

22-3

22-4

Interconversion of Acid Derivatives by Nucleophilic Acyl Substitution
22-5:

22-6:

22-7:
Answer: B
Transesterification
22-8:
Answer: D
22-9:
Under acidic conditions, the carbonyl oxygen atom is protonated, making it a better electrophile for the reaction to occur. Under basic conditions, the alcohol we are trying to add is deprotonated, making it a better nucleophile.
22-10:

Hydrolysis of Carboxylic Acid Derivatives
22-11:

22-12:

22-13:

Reduction of Acid Derivatives
22-14:

22-15:

22-16:
Answer: C
Reactions of Acid Derivatives with Organometallic Reagents
22-17:

22-18:
Answer: C
22-19:
A possibly better route of synthesis:
