Amide formation
Ammonia adds to the acyl carbonyl to form a tetrahedral intermediate. Carbonyl re-formation expels chloride, and proton transfer gives benzamide; additional ammonia captures the acid as ammonium chloride.
- Reagents
- Excess NH3
- Conditions
- Controlled acylation with ammonia
- Reaction class
- Amide formation
- Equation
- C6H5COCl + 2NH3 -> C6H5CONH2 + NH4Cl
Overview
Ammonia adds to the acyl carbonyl to form a tetrahedral intermediate. Carbonyl re-formation expels chloride, and proton transfer gives benzamide; additional ammonia captures the acid as ammonium chloride.
Transformation
- Equation
- C6H5COCl + 2NH3 -> C6H5CONH2 + NH4Cl
- Reactants
- Benzoyl chloride + 2 Ammonia
- Products
- Benzamide + Ammonium chloride
- Reagents
- Excess NH3
- Environment
- Controlled acylation with ammonia
- Reaction class
- Amide formation
- Mechanism
- nucleophilic addition-elimination
- Evidence level
- source-backed molecular example
Scope and limitations
- Scope
- Ammonia supplies the amide nitrogen and neutralises HCl.
- Limitations
- Competing hydrolysis is possible in water; the second ammonia equivalent is not incorporated into benzamide.
Related reactions
- Acyl chloride preparation: Benzoic acid → Benzoyl chloride
Reaction with phosphorus(V) chloride replaces the carboxyl OH group with chlorine, retaining the acyl carbon and aromatic ring. The new acyl chloride is more susceptible to nucleophilic substitution, while POCl3 and HCl account for the remaining atoms.
- Ester formation: Benzoyl chloride → Ethyl benzoate
Ethanol oxygen attacks the acyl carbonyl carbon. Loss of chloride and proton transfer restore C=O and form the ester, with ethanol contributing the ethoxy group and HCl produced in the overall equation.
References
- Organic Chemistry: Chemistry of Acid HalidesJohn McMurry · OpenStax Organic Chemistry · 2023
Supports acid-halide preparation with thionyl chloride and nucleophilic acyl substitution chemistry, including tetrahedral intermediates, hydrolysis, alcoholysis and amine acylation at acid chlorides.