### SN1 and SN2 Reaction Mechanisms**a) Describe the general steps in the mechanism for an SN1 reaction and an SN2 reaction.****SN1 Reaction Mechanism:**1. **Unimolecular Step:** The reaction begins with the dissociation of the substrate to form a carbocation intermediate. This step is unimolecular and involves only the substrate.2. **Carbocation Formation:** The leaving group departs, resulting in a positively charged carbocation.3. **Nucleophilic Attack:** The nucleophile attacks the carbocation, leading to the formation of the substitution product.**SN2 Reaction Mechanism:**1. **Bimolecular Step:** The nucleophile attacks the substrate at the same time as the leaving group departs. This is a concerted mechanism, meaning it happens in a single step.2. **Backside Attack:** The nucleophile approaches the substrate from the side opposite to the leaving group, resulting in an inversion of configuration at the carbon center.**b) Discuss in detail the similarities and differences between these two mechanisms.****Similarities:**- Both are substitution reactions involving the replacement of a leaving group by a nucleophile.- Both mechanisms can result in the formation of similar types of products.**Differences:**- **Mechanism Type:** SN1 is a two-step mechanism involving a carbocation intermediate, while SN2 is a single-step, concerted process.- **Order of Reaction:** SN1 is first-order, depending only on the concentration of the substrate, while SN2 is second-order, depending on the concentrations of both the substrate and nucleophile.- **Stereochemistry:** SN1 often leads to racemization due to the planar nature of the carbocation, whereas SN2 typically results in inversion of stereochemistry.- **Substrate Preference:** SN1 reactions prefer more stable carbocations, such as tertiary carbons, while SN2 reactions favor primary substrates to avoid steric hindrance.

The reaction in which an atom or group is substitutes by any other atom or group is known as substitution reaction.a. The Steps of the mechanism of SN1 reaction is shown below: Step 1: Breaking of carbon halogen bond (C-X) is an endothermic process and formation of carbocation. Step 2: The formed carbocation is reacted with the nucleophile. Step 3: Deprotonation will takes place to get the final product. The Steps of the mechanism of SN2 reaction is shown below: In SN2 reaction; the nucleophile attacks from the backside of the substrate and form a transition state in which nucleophile attacked on the back side and leaving group leaves in the front side and then product will be formed by the leaving leaves from the substrate.b. The similarity between the SN1 and SN2 reaction is both the nucleophilic substitution reaction. The difference between the SN1 and SN2 is shown below: