Which substrate will undergo a reaction with ethanol fastest at room temperature?

• A.
• B.
• C.
• D.

Answer: (C)

Verified step by step guidance

1. Identify the type of reaction: The reaction of a substrate with ethanol is typically a nucleophilic substitution reaction. Ethanol can act as a nucleophile.
2. Determine the mechanism: The reaction can proceed via SN1 or SN2 mechanism. SN1 is favored by tertiary substrates and polar protic solvents, while SN2 is favored by primary substrates and polar aprotic solvents.
3. Analyze the substrates: Look at the structure of each substrate. The first image is a primary alkyl bromide, the second is methyl bromide, the third is an allylic bromide, and the fourth is a secondary alkyl bromide.
4. Consider the reactivity: Methyl and primary substrates typically undergo SN2 reactions quickly. However, allylic substrates can also react quickly due to resonance stabilization of the transition state.
5. Evaluate the conditions: Ethanol is a polar protic solvent, which can favor SN1 reactions, but it can also participate in SN2 reactions with good nucleophiles. Consider the stability of carbocations for SN1 and steric hindrance for SN2.