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
-Based on the structure of acetaminophen shown in the passage, in which region of the infrared spectrum will it most likely show a strong absorption?

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
-Based on the structure of acetaminophen shown in the passage, in which region of the infrared spectrum will it most likely show a strong absorption?

Quizplus · Accepted Answer

11ecba2d_125a_11be_a3bf_b3d7997020bf_MD0008_00 Acetaminophen contains several functional groups, including a phenol (hydroxyl group), aromatic ring, and amide that would show a strong absorption in the infrared (IR) spectrum. Each functional group shows absorption at a different frequency depending on the type of bond the functional group contains. The carbonyl (C=O) group from an amide shows an absorption from the 1690-1650 cm⁻¹ region in the IR spectrum. (Choices B, C, and D) In the IR spectrum, an alkyne CΞC stretch absorbs from 2150-2,100 cm⁻¹, a nitrile CΞN stretch absorbs from 2260-2240 cm⁻¹, and an aldehyde C-H stretch absorbs from 2850-2750 cm⁻¹. Acetaminophen does not contain these groups; therefore, it will not have a strong absorbance at these frequencies. Educational objective: Functional groups show absorption in the infrared spectrum at different frequencies depending on the bond type present in the particular functional group. Characteristic functional group absorptions include 3650-3200 cm⁻¹ (alcohol and phenol O−H stretch); 3550-3060 cm⁻¹ (amide N-H stretch); 3100 cm⁻¹ (sp² C-H stretch); 3000-2875 cm⁻¹ (sp³ C-H stretch); 2260-2,100 cm⁻¹ (triple bonds); and 1850-1650 cm⁻¹ (C=O stretch).

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