Describe and give examples of base-catalyzed nucleophilic addition reactions occurring at the carboxy1 carbon.

Base-catalyzed nucleophilic addition reactions involve a nucleophile reacting with an electrophile in the presence of a base catalyst. In this case, the electrophile is the carboxyl carbon in a molecule. The carboxyl carbon is the carbon atom within the carboxyl functional group (COOH), which consists of a carbonyl group (C=O) bonded to a hydroxyl group (O-H). In the reaction mechanism, the base catalyst abstracts a proton from the hydroxyl group, and the nucleophile attacks the carboxyl carbon. This results in the addition of the nucleophile to the carboxyl carbon, forming a new molecule. Examples of such reactions include the reaction of acetic acid with an alkoxide ion (\( CH_3COOH + R'O^- \rightarrow CH_3COOR + OH^- \)) to form an ester, and the reaction of a carboxylic acid with ammonia (\[ RCOOH + NH_3 \rightarrow RCONH_2 + H_2O \]) to form an amide.