The reaction below will occur most rapidly in which of the following solvents?CH3Br + OH^- → CH3OH + Br^-Choose the solvent that will best promote the rate of this reaction.

• A. Hexane (C6H14)
• B. Diethyl ether (C4H10O)
• C. Ethanol (C2H5OH)
• D. Water (H2O)

Answer: (D)

Verified step by step guidance

1. Identify the type of reaction: The given reaction is a nucleophilic substitution where OH⁻ attacks CH₃Br, displacing Br⁻. This is typically an SN2 reaction because the substrate is a primary alkyl halide.
2. Understand the role of the solvent: In SN2 reactions, the solvent can either stabilize the nucleophile or the transition state. Polar aprotic solvents tend to increase the rate by not strongly solvating the nucleophile, while polar protic solvents can hydrogen bond and stabilize the nucleophile, often slowing the reaction.
3. Analyze the solvent options: Hexane is nonpolar and will not stabilize ions well; diethyl ether is a polar aprotic solvent; ethanol and water are polar protic solvents, with water being more polar and better at stabilizing ions due to strong hydrogen bonding.
4. Consider the nucleophile's strength: OH⁻ is a charged nucleophile and is better stabilized in polar protic solvents like water, which can also stabilize the transition state and the leaving group (Br⁻), facilitating the reaction.
5. Conclude which solvent promotes the fastest reaction: Water, being highly polar and protic, stabilizes both the nucleophile and the transition state effectively, thus increasing the rate of the SN2 reaction compared to the other solvents listed.