A. Which reacts faster in an SN 2 reaction? b. Which reacts...

Key Concepts

SN2 Reaction Mechanism

The SN2 reaction is a one-step, bimolecular process where the nucleophile attacks the electrophilic carbon from the opposite side of the leaving group. Its rate is highly sensitive to steric hindrance, meaning that substrates with less crowded (typically primary) centers facilitate a faster backside attack, resulting in a faster reaction.

SN1 Reaction Mechanism

The SN1 reaction occurs in two steps with the initial formation of a carbocation intermediate followed by nucleophilic attack. The rate-determining step is the generation of the carbocation, so the reaction speed depends greatly on the stability of the intermediate. Substrates that can form more stable (usually tertiary) carbocations react faster under SN1 conditions.

E1 Reaction Mechanism

The E1 mechanism is similar to SN1 in that it begins with the formation of a carbocation intermediate. After its formation, a base removes a proton to form a double bond, resulting in an alkene. As with SN1 reactions, the efficiency of an E1 reaction is increased by carbocation stability, which generally favors more substituted carbons.

Steric Hindrance

Steric hindrance refers to the impact of bulky groups around the reactive center on the accessibility of that site to an attacking nucleophile. In SN2 reactions, lower steric hindrance (as seen in primary substrates) enhances the reaction rate, while higher steric hindrance (common in secondary and tertiary substrates) slows it down.

Carbocation Stability

Carbocation stability is a key factor in unimolecular reactions such as SN1 and E1. More substituted carbocations (like tertiary ones) are stabilized by hyperconjugation and inductive effects, which lower the energy barrier for their formation and increase the reaction rate.

Transcript

Please give Ace some feedback