Esterification Knowledge-Based Practice

Questions

1. 1.

   During acid-catalyzed Fischer esterification, what change occurs in the hybridization and geometry of the carbonyl carbon atom upon nucleophilic attack by the alcohol?

   • A) It changes from tetrahedral $sp^3$ to trigonal planar $sp^2$.
   • B) It changes from linear $sp$ to trigonal planar $sp^2$.
   • C) It remains trigonal planar $sp^2$ with no change in geometry.
   • D) It changes from trigonal planar $sp^2$ to tetrahedral $sp^3$.
2. 2.

   In the acid-catalyzed Fischer esterification of a carboxylic acid with an alcohol, which species acts as the leaving group expelled from the tetrahedral intermediate to reform the carbonyl group?

   • A) Hydroxide ion ($OH^-$)
   • B) A neutral water molecule ($H_2O$)
   • C) An alkoxide ion ($RO^-$)
   • D) A hydronium ion ($H_3O^+$)
3. 3.

   Fischer esterification between a carboxylic acid and an alcohol is a reversible, equilibrium-limited process. Which of the following experimental strategies is commonly employed to drive the equilibrium toward a high yield of the ester product?

   • A) Adding an excess of water into the reaction vessel throughout the reflux
   • B) Diluting the mixture extensively with an aqueous solvent to lower reactant concentrations
   • C) Removing water continuously from the reaction mixture using a Dean-Stark apparatus or a desiccant
   • D) Neutralizing the acid catalyst with a strong base as soon as the reaction begins
4. 4.

   During the acid-catalyzed Fischer esterification of a carboxylic acid with an alcohol, what is the primary role of the acid catalyst in initiating the reaction?

   • A) Protonation of the carbonyl oxygen of the carboxylic acid, which increases the electrophilicity of the carbonyl carbon
   • B) Deprotonation of the alcohol hydroxyl group, which generates a strongly nucleophilic alkoxide ion
   • C) Direct protonation of the carboxylic acid hydroxyl group, causing spontaneous loss of water before alcohol attack
   • D) Protonation of the alcohol oxygen, which converts the alcohol molecule into a potent electrophile
5. 5.

   Which of the following correctly identifies the ester produced from the acid-catalyzed reaction between butanoic acid and ethanol, along with the origin of the bridging alkoxy oxygen atom in the ester?

   • A) Ethyl butanoate, with the bridging oxygen atom originating from ethanol
   • B) Butyl ethanoate, with the bridging oxygen atom originating from butanoic acid
   • C) Ethyl butanoate, with the bridging oxygen atom originating from butanoic acid
   • D) Butyl ethanoate, with the bridging oxygen atom originating from ethanol

Answers and step-by-step solutions appear after you finish the test.