Question

The starting material, 2-(hydroxymethyl)tetrahydrofuran, undergoes a three-step reaction. First, the primary alcohol (-CH₂OH) is converted to an alkyl chloride (-CH₂Cl) using thionyl chloride (SOCl₂) and pyridine. Second, the alkyl chloride reacts with magnesium (Mg) in diethyl ether to form a Grignard reagent (-CH₂MgCl). Finally, treatment with a proton source (H⁺) protonates the Grignard reagent, converting the -CH₂MgCl group to a methyl group (-CH₃). Thus, the overall transformation replaces the -CH₂OH group with a -CH₃ group, yielding 2-methyltetrahydrofuran.

Starting Material (X): 2-(hydroxymethyl)tetrahydrofuran

Reaction Steps:

1. Alcohol to Alkyl Chloride: 2-(hydroxymethyl)tetrahydrofuran + SOCl₂ $\xrightarrow{pyridine, \Delta}$ 2-(chloromethyl)tetrahydrofuran

2. Alkyl Chloride to Grignard Reagent: 2-(chloromethyl)tetrahydrofuran + Mg $\xrightarrow{(C_2H_5)_2O}$ Tetrahydrofuran-2-ylmethylmagnesium chloride

3. Grignard Reagent Protonation: Tetrahydrofuran-2-ylmethylmagnesium chloride + H⁺ $\rightarrow$ 2-methyltetrahydrofuran

Product (Option A): 2-methyltetrahydrofuran

• A. 2-methyltetrahydrofuran
• B. 2-ethyltetrahydrofuran
• C. 2-propyltetrahydrofuran
• D. 2-butyltetrahydrofuran

Answer 1

Answer: (A)

2-methyltetrahydrofuran

Answer 2

The starting material, 2-(hydroxymethyl)tetrahydrofuran, is converted to an alkyl chloride using thionyl chloride and pyridine. This alkyl chloride then forms a Grignard reagent upon reaction with magnesium. Finally, protonation of the Grignard reagent yields 2-methyltetrahydrofuran, effectively replacing the -CH₂OH group with a -CH₃ group.