Sn1 (Substitution Nucleophilic Unimolecular) and Sn2 (Substitution Nucleophilic Bimolecular) reactions are two types of nucleophilic substitution reactions. The main difference between them is the rate-determining step. In Sn1 reactions, the rate of the reaction is determined by the formation of a carbocation intermediate, while in Sn2 reactions, the rate is determined by the attack of the nucleophile on the substrate.
The rate of Sn1 and Sn2 reactions can be influenced by several factors, including the strength of the nucleophile, the type of leaving group, the solvent polarity, and the steric hindrance of the substrate. In Sn1 reactions, the rate is also affected by the stability of the carbocation intermediate, while in Sn2 reactions, the rate is affected by the steric hindrance of the substrate and the leaving group.
Polar protic solvents, such as water and alcohols, favor Sn1 reactions. This is because these solvents stabilize the carbocation intermediate through hydrogen bonding, which increases the rate of the reaction. Additionally, polar protic solvents can also solvate the nucleophile and hinder its attack on the substrate, making Sn2 reactions less favorable.
No, primary alkyl halides cannot undergo Sn1 reactions. This is because the formation of a primary carbocation is highly unfavorable due to the lack of neighboring alkyl groups to stabilize the positive charge. Therefore, primary alkyl halides mainly undergo Sn2 reactions.
Sn1 reactions typically result in a racemic mixture of products, meaning that both enantiomers are formed in equal amounts. This is because the carbocation intermediate can be attacked from either side. On the other hand, Sn2 reactions result in an inversion of stereochemistry, where the nucleophile attacks the substrate from the side opposite to the leaving group, resulting in the formation of the opposite enantiomer.