Answer the following questions for this SN 2 reaction: CH3 CH2 CH2 CH2 Br+NaOH ⟶CH3 CH2 CH2

step 1 Let's look at this reaction. The rate of reaction can be represented like this. CH3, CH2, CH2, C

Answer the following questions for this SN 2 reaction: CH3...

Answer the following questions for this $S_{\mathrm{N}} 2$ reaction: $$\begin{aligned} \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{Br}+\mathrm{NaOH} & \longrightarrow \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH}+ \mathrm{NaBr} \end{aligned}$$ (a) What is the rate expression for the reaction? (b) Draw the reaction profile for the reaction. Label all parts. Assume that the products are lower in energy than the reactants. (c) What is the effect on the rate of the reaction of doubling the concentration of $n$ -butyl bromide? (d) What is the effect on the rate of the reaction of halving the concentration of sodium hydroxide?

Answer the following questions for this $S_{\mathrm{N}} 2$ reaction: $$\begin{aligned}
\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{Br}+\mathrm{NaOH} & \longrightarrow
\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH}+ \mathrm{NaBr}
\end{aligned}$$
(a) What is the rate expression for the reaction?
(b) Draw the reaction profile for the reaction. Label all parts. Assume that the products are lower in energy than the reactants.
(c) What is the effect on the rate of the reaction of doubling the concentration of $n$ -butyl bromide?
(d) What is the effect on the rate of the reaction of halving the concentration of sodium hydroxide?

Key Concepts

Rate Expression

For an SN2 reaction, the rate expression is derived from its bimolecular nature, leading to a rate law that is second order overall. The rate is directly proportional to the concentrations of both the substrate and the nucleophile, typically expressed as rate = k[substrate][nucleophile]. This signifies that any change in the concentration of either reactant will correspondingly affect the reaction rate.

Reaction Coordinate Diagram

A reaction coordinate diagram for an SN2 reaction illustrates the energy changes during the reaction. It typically shows a single transition state where the energy reaches a maximum, with the reactants at a higher energy level than the products, reflecting an exothermic reaction. Key features include the activation energy, which is the energy difference between the reactants and the transition state, as well as the overall energy drop from reactants to products.

SN2 Reaction Mechanism

The SN2 reaction mechanism involves a bimolecular nucleophilic substitution where bond breaking and bond forming occur simultaneously in a single concerted step. The nucleophile attacks the electrophilic carbon from the backside, leading to inversion of configuration at the carbon center. This one-step process is characterized by its dependency on both the substrate and the nucleophile, making it sensitive to steric hindrance and solvent effects.

Effect of Reactant Concentration on Reaction Rate

Since the SN2 reaction rate is dependent on the concentration of both the substrate and the nucleophile, any variation in their concentrations has a direct impact on the reaction rate. Doubling the concentration of one reactant, while keeping the other constant, will result in a doubling of the overall reaction rate, whereas halving it will lead to a corresponding decrease in the rate. This emphasizes the direct relationship between reactant concentration and the reaction kinetics in bimolecular processes.

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