Passage
Students perform a synthesis of a carboxylic acid derivative.They mix a 10.00-mL sample of hexanoic acid, 2.33 mL of ethanol, and 0.64 mL of concentrated sulfuric acid in a flask with a water condenser fitted to its neck. The mixture is boiled for one hour and then poured into water when the reaction is complete. The aqueous and organic layers are separated, and the organic layer is washed once with NaHCO 3 and twice with water. Solid Na 2 SO 4 is added to the organic layer to remove any water present. The organic layer and Na 2 SO 4 are separated by filtration. The filtrate is purified by fractional distillation to yield the carboxylic acid derivative, a colorless liquid.
-Which of the following reactions will convert hexanoic acid and the carboxylic acid derivative described in the passage to the same product?

Question

Passage
Students perform a synthesis of a carboxylic acid derivative.They mix a 10.00-mL sample of hexanoic acid, 2.33 mL of ethanol, and 0.64 mL of concentrated sulfuric acid in a flask with a water condenser fitted to its neck.  The mixture is boiled for one hour and then poured into water when the reaction is complete.  The aqueous and organic layers are separated, and the organic layer is washed once with NaHCO 3 and twice with water.  Solid Na 2 SO 4 is added to the organic layer to remove any water present.  The organic layer and Na 2 SO 4 are separated by filtration.  The filtrate is purified by fractional distillation to yield the carboxylic acid derivative, a colorless liquid.
-Which of the following reactions will convert hexanoic acid and the carboxylic acid derivative described in the passage to the same product?

Quizplus · Accepted Answer

11ecba2d_12b3_55ad_a3bf_11d7f5a3756f_MD0008_00 Reducing agents decrease an atom's oxidation state. The reduction of a carbon atom decreases the number of bonds it has to electronegative atoms (including oxygen, nitrogen, and halogens), and increases the number of bonds to less electronegative atoms (typically hydrogen). Hydride reagents, such as LiAlH₄ and NaBH₄, are common reducing agents and are made of a metal surrounded by one or more hydride ions. The hydride ion acts as a nucleophile and attacks an electrophilic atom. LiAlH₄ is a strong reducing agent and will reduce carbonyl compounds to alcohols. Aldehydes, esters, and carboxylic acids will be reduced to primary alcohols, and ketones will be reduced to secondary alcohols. The reaction mixture contains the ester ethyl hexanoate and unreacted hexanoic acid. If these two compounds are reacted with LiAlH₄, they would both be reduced to the six-carbon primary alcohol hexanol. Ethyl hexanoate will also produce ethanol as a side product when reduced with LiAlH₄. (Choice A) A base-catalyzed aldol condensation does require carbonyl compounds, but the required compounds are ketones and aldehydes rather than carboxylic acids and esters. (Choice B) Decarboxylation occurs with β-dicarbonyl compounds. Neither ethyl hexanoate nor hexanoic acid contains a β-carbonyl, so they will not undergo decarboxylation. (Choice C) NaBH₄ is a reducing agent rather than an oxidizing agent. Furthermore, NaBH₄ is a mild reducing agent and cannot reduce carboxylic acids or esters; therefore, hexanoic acid and ethyl hexanoate would not react with NaBH₄. Educational objective: Reducing agents decrease an atom's oxidation state and reduce the number of bonds carbon has to electronegative atoms while increasing the number of bonds to less electronegative atoms (commonly hydrogen). Hydride reagents, such as LiAlH₄ and NaBH₄, contain a metal atom surrounded by hydride ions. LiAlH₄ is a strong reducing agent and will reduce carbonyl compounds, including esters and carboxylic acids, to alcohols.

Passage Students Perform a Synthesis of a Carboxylic Acid Derivative.They Mix