Question

multiple choice 1 point
which of the following best explains why methyl halides are highly reactive in s_n2 reactions?
methyl halides easily form carbocations.
methyl halides have weak bonds.
methyl halides contain a good leaving group.
methyl halides are sterically unhindered.

Explanation:

In \(S_N2\) reactions, the nucleophile attacks the carbon atom from the back - side of the leaving group. Methyl halides (\(CH_3X\), where \(X\) is a halogen) have only three small hydrogen atoms attached to the carbon atom bonded to the halogen. There is no bulky alkyl group to hinder the approach of the nucleophile.

• Option A: Methyl carbocations (\(CH_3^+\)) are highly unstable. \(S_N2\) reactions do not involve carbocation formation.
• Option B: The bond strength of the \(C - X\) bond in methyl halides is not the main reason for their high \(S_N2\) reactivity. For example, \(C - I\) bonds are relatively weak, but the steric factor is more crucial for \(S_N2\) in methyl halides.
• Option C: While halides (\(X^-\)) are good leaving groups, this property is common to many alkyl halides (not just methyl halides). The key differentiating factor for methyl halides in \(S_N2\) is steric.

Answer:

D. Methyl halides are sterically unhindered.