SN₂ chemical reaction Brief

 

The SN2 mechanism describes 

a type of nucleophilic substitution reaction where a nucleophile replaces a leaving group in a one-step process. In the specific case of methyl bromide reacting with aqueous KOH, the nucleophile is the hydroxide ion (OH-) from KOH, and the leaving group is the bromide ion (Br-).

Here's a step-by-step breakdown of the SN2 mechanism:

 * Nucleophile Attack: The hydroxide ion (OH-) acts as a nucleophile, meaning it is attracted to positive charges. It approaches the methyl bromide molecule from the opposite side of the bromine atom. This is called "backside attack."

 * Transition State: As the hydroxide ion approaches, it starts forming a bond with the carbon atom, while the bond between carbon and bromine starts breaking. This leads to a transition state where the carbon atom is partially bonded to both the hydroxide ion and the bromine atom. The transition state is unstable and high in energy.

 * Leaving Group Departure: The carbon-bromine bond completely breaks, and the bromine atom leaves as a bromide ion (Br-). This is the leaving group.

 * Product Formation: The hydroxide ion is now fully bonded to the carbon atom, forming methanol (CH3OH) as the product.

Key Features of the SN2 Mechanism:

 * One-step reaction: The nucleophile attack and leaving group departure occur simultaneously.

 * Backside attack: The nucleophile attacks from the opposite side of the leaving group, leading to inversion of configuration at the carbon atom.

 * Second-order kinetics: The reaction rate depends on the concentration of both the nucleophile and the substrate (methyl bromide).

 * Steric hindrance: SN2 reactions are favored in less sterically hindered molecules. Methyl bromide, being a primary alkyl halide, is a good substrate for SN2 reactions.

In this chemical reaction of methyl bromide with aqueous KOH follows an SN2 mechanism, resulting in the formation of methanol and bromide ion. The reaction involves a one-step backside attack of the hydroxide ion on methyl bromide, leading to inversion of configuration and the formation of the product.