Fundamentals of Organic ChemistryChemistryCarboxylic Acid Derivatives
To obtain the maximum yield of the acid amide in the reaction RCOCl + NH ₃ RCONH ₂ , which of the following conditions is most appropriate?
Options
- AThe acid chloride and ammonia are reacted in a 2:1 molar ratio.
- BThe acid chloride and ammonia are reacted in an equimolar ratio.
- CAll three of the above ratios give a nearly similar yield.
- DThe acid chloride and ammonia are reacted in a 1:2 molar ratio.
Correct answer
D. The acid chloride and ammonia are reacted in a 1:2 molar ratio.
Step-by-step solution
The reaction between an acid chloride and ammonia proceeds as follows: RCOCl + NH ₃ RCONH ₂ + HCl The HCl produced during the reaction is an acid and will immediately react with the unreacted basic ammonia to form ammonium chloride: NH ₃ + HCl NH ₄ Cl Adding the two equations gives the overall reaction: RCOCl + 2 NH ₃ RCONH ₂ + NH ₄ Cl For every mole of acid chloride, two moles of ammonia are consumed (one acts as a nucleophile to form the amide, and the other acts as a base to neutralize the HCl byproduct). Theref