Practice your electron-pushing skills by drawing a mechanism for the following Sₙ2 reactions.


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Verified step by step guidance

1. Identify the nucleophile and the electrophile in the reaction. The nucleophile is the species that donates an electron pair, while the electrophile is the species that accepts an electron pair.
2. Recognize that an Sₙ2 reaction involves a single concerted step where the nucleophile attacks the electrophile from the opposite side of the leaving group, leading to an inversion of configuration at the carbon center.
3. Draw the nucleophile approaching the electrophilic carbon atom from the side opposite to the leaving group. Use a curved arrow to show the movement of the electron pair from the nucleophile to the electrophilic carbon.
4. Simultaneously, draw another curved arrow from the bond between the electrophilic carbon and the leaving group to the leaving group itself, indicating that the leaving group is departing with the electron pair.
5. Ensure that the final product shows the nucleophile bonded to the carbon atom, with the leaving group completely detached, and note the inversion of stereochemistry at the carbon center.

Key Concepts

Sₙ2 Mechanism

The Sₙ2 mechanism, or bimolecular nucleophilic substitution, involves a single concerted step where a nucleophile attacks an electrophile, leading to the simultaneous displacement of a leaving group. This reaction is characterized by a backside attack, resulting in inversion of configuration at the chiral center. Understanding this mechanism is crucial for predicting the outcome of reactions involving primary and secondary alkyl halides.

Nucleophiles and Electrophiles

Nucleophiles are species that donate an electron pair to form a chemical bond, while electrophiles are electron-deficient species that accept electron pairs. In Sₙ2 reactions, the strength and nature of the nucleophile significantly influence the reaction rate and outcome. Recognizing the properties of these species helps in predicting reactivity and understanding the mechanism.

Leaving Groups

A leaving group is an atom or group that can depart from the parent molecule during a chemical reaction, taking with it the electrons from the bond. Good leaving groups, such as halides or sulfonates, stabilize the negative charge after departure, facilitating the Sₙ2 reaction. Identifying and evaluating the leaving group is essential for determining the feasibility and rate of the reaction.