Which of the following is the major product when an acid chloride reacts with ${\mathrm{NH}}_3$ in a nucleophilic acyl substitution reaction?

• A. A carboxylic acid, $R-{\mathrm{COOH}}_{}$
• B. A primary amide, $R-{\mathrm{CONH}}_2$
• C. A secondary amide, $R-{\mathrm{CONH}}_{\mathrm{CH}}{3}_{}$
• D. An ester, $R-{\mathrm{COOCH}}_3$

Answer: (B)

Verified step by step guidance

1. Identify the reactants: an acid chloride (R-COCl) and ammonia (NH\_3). Recognize that this is a nucleophilic acyl substitution reaction where NH\_3 acts as the nucleophile.
2. Recall the mechanism of nucleophilic acyl substitution: the nucleophile attacks the electrophilic carbonyl carbon of the acid chloride, forming a tetrahedral intermediate.
3. Understand that the tetrahedral intermediate then collapses, expelling the chloride ion (Cl\^-) as a leaving group, which restores the carbonyl functionality.
4. Since the nucleophile is ammonia (NH\_3), the product formed after substitution is a primary amide (R-CONH\_2), because ammonia provides an NH\_2 group attached to the carbonyl carbon.
5. Eliminate other options: a carboxylic acid would require hydrolysis, a secondary amide would require a substituted amine, and an ester would require an alcohol as nucleophile, so the major product here is the primary amide.