Passage
The drug paracetamol, also known as acetaminophen, is used to relieve pain and fever, and is a metabolite of the antipyretic drug phenacetin (Figure 1) . These two drugs have similar medicinal properties, but phenacetin has been shown to be carcinogenic and cause kidney damage. Acetaminophen is a safer alternative to phenacetin when taken in therapeutic doses.
Figure 1 Structure of phenacetinA student synthesizes acetaminophen in a laboratory from phenol according to the reactions shown. The synthesis begins with the nitration of phenol by sodium nitrate (NaNO₃) to produce the mixture of the isomers 2-nitrophenol and 4-nitrophenol (Reaction 1) . These isomers can be easily separated by steam distillation to isolate the desired product, 4-nitrophenol. Reduction of the nitro group with sodium borohydride (NaBH₄) (Reaction 2) is followed by acetylation of the amine with acetic anhydride (Reaction 3) to afford the final product, acetaminophen.
Reaction 1
Reaction 2
Reaction 3
-Which of the following statements most accurately describes the component that remains in the reaction flask during the steam distillation?

Question

Passage
The drug paracetamol, also known as acetaminophen, is used to relieve pain and fever, and is a metabolite of the antipyretic drug phenacetin (Figure 1) . These two drugs have similar medicinal properties, but phenacetin has been shown to be carcinogenic and cause kidney damage. Acetaminophen is a safer alternative to phenacetin when taken in therapeutic doses.

Figure 1 Structure of phenacetinA student synthesizes acetaminophen in a laboratory from phenol according to the reactions shown. The synthesis begins with the nitration of phenol by sodium nitrate (NaNO₃) to produce the mixture of the isomers 2-nitrophenol and 4-nitrophenol (Reaction 1) . These isomers can be easily separated by steam distillation to isolate the desired product, 4-nitrophenol. Reduction of the nitro group with sodium borohydride (NaBH₄) (Reaction 2) is followed by acetylation of the amine with acetic anhydride (Reaction 3) to afford the final product, acetaminophen.

Reaction 1

Reaction 2

Reaction 3
-Which of the following statements most accurately describes the component that remains in the reaction flask during the steam distillation?

Quizplus · Accepted Answer

11ecba2d_1258_3cf7_a3bf_dda305a0f290_MD0008_00 Distillation is a purification technique used to separate molecules based on boiling point. A liquid mixture is heated to a temperature that overcomes the intermolecular forces keeping the compound in the liquid phase. The vapors then condense in the collection flask as a liquid. A molecule that participates in strong intermolecular forces will have a higher boiling point than molecules with weak intermolecular forces. Hydrogen bonding can be intermolecular (between two molecules) or intramolecular (within the same molecule), and therefore can have a significant impact on a molecule's boiling point. The difference in connectivity of the constitutional isomers 2-nitrophenol and 4-nitrophenol causes the molecules to experience different intermolecular forces, which contributes to the difference in their boiling points. Because the hydroxyl and nitro groups in 2-nitrophenol are ortho and therefore close in proximity to each other, the hydrogen from the hydroxyl group can hydrogen bond intramolecularly with the lone pair of electrons on the nitro group. This intramolecular bonding decreases the number of intermolecular bonds that can form, thereby decreasing the boiling point of the compound. Because the hydroxyl and nitro groups on 4-nitrophenol are para, they are able to hydrogen bond intermolecularly but not intramolecularly. Intermolecular bonds hold the molecules of 4-nitrophenol together, thereby increasing the boiling point and causing it to stay in the flask while 2-nitrophenol distills. (Choices A and C) 2-nitrophenol experiences less intermolecular hydrogen bonding than 4-nitrophenol, and therefore has a lower boiling point and distills more rapidly than 4-nitrophenol. (Choice D) 4-nitrophenol experiences more intermolecular hydrogen bonding causing it to have a higher boiling point than 2-nitrophenol. Educational objective: Distillation separates compounds based on their boiling point. Constitutional isomers can experience different intermolecular forces, contributing to the difference in their boiling points. The isomer that experiences increased intermolecular hydrogen bonding has a higher boiling point compared to the isomer that experiences increased intramolecular hydrogen bonding.

Passage the Drug Paracetamol, Also Known as Acetaminophen, Is Used to to Relieve