Consider the following statements in reference to \(\mathrm{S}_{\mathrm{N}} 1, \mathrm{~S}_{\mathrm{N}} 2, \mathrm{E} 1\), and \(\mathrm{E} 2\) reactions of haloalkanes. To which mechanism (s), if any, does each statement apply? (a) Involves a carbocation intermediate. (b) Is first order in haloalkane and first order in nucleophile. (c) Involves inversion of configuration at the site of substitution. (d) Involves retention of configuration at the site of substitution. (e) Substitution at a stereocenter gives predominantly a racemic product. (f) Is first order in haloalkane and zero order in base. (g) Is first order in haloalkane and first order in base. (h) Is greatly accelerated in protic solvents of increasing polarity. (i) Rearrangements are common. (j) Order of reactivity of haloalkanes is \(3^{\circ}>2^{\circ}>1^{\circ}\). (k) Order of reactivity of haloalkanes is methyl \(>1^{\circ}>2^{\circ}>3^{\circ}\).

Step by step solution

01

Identify the mechanisms with carbocation intermediates

In the SN1 and E1 reactions, a carbocation intermediate is formed. In the SN2 and E2 reactions, there is no carbocation intermediate. #a) Answer: SN1 and E1 #b) Is first order in haloalkane and first order in nucleophile.#

02

Identify the mechanisms with first-order dependence on both haloalkane and nucleophile

In the SN2 reaction, the rate is dependent on both the haloalkane and nucleophile concentrations. The E2 reaction is also first order in both haloalkane and base (which acts as the nucleophile). #b) Answer: SN2 and E2 #c) Involves inversion of configuration at the site of substitution.#

03

Identify the mechanisms that involve inversion of configuration

In the SN2 mechanism, the nucleophile attacks from the opposite side of the leaving group, causing the inversion of configuration at the reaction site. #c) Answer: SN2 #d) Involves retention of configuration at the site of substitution.#

04

Identify the mechanisms that involve retention of configuration

In the SN1 mechanism, the intermediate carbocation can be attacked by the nucleophile from both sides, with equal probability, leading to a mixture of retention and inversion of configuration. However, if there's a rearrangement, retention of the original configuration might be observed. #d) Answer: SN1 (with the rearrangement) #e) Substitution at a stereocenter gives predominantly a racemic product.#

05

Identify the mechanisms that produce a racemic product

In the SN1 reaction, a racemic mixture of products is formed due to the equal probability of nucleophilic attack from both sides of the carbocation intermediate. #e) Answer: SN1 #f) Is first order in haloalkane and zero order in base.#

06

Identify the mechanisms with first-order dependence in haloalkane and zero order in base

In the E1 reaction, the rate is dependent on the haloalkane concentration and has zero order in base. #f) Answer: E1 #g) Is first order in haloalkane and first order in base.#

07

Identify the mechanisms with first-order dependence in both haloalkane and base

In the E2 reaction, the rate is dependent on both the haloalkane and base concentrations. #g) Answer: E2 #h) Is greatly accelerated in protic solvents of increasing polarity.#

08

Identify the mechanisms that are accelerated in polar protic solvents

In the SN1 and E1 reactions, the rate increases with the increasing polarity of the protic solvent, as it helps stabilize the carbocation intermediate. #h) Answer: SN1 and E1 #i) Rearrangements are common.#

09

Identify the mechanisms with common rearrangements

In the SN1 reaction, the carbocation intermediate can undergo rearrangement to form a more stable carbocation. #i) Answer: SN1 #j) Order of reactivity of haloalkanes is \(3^{\circ}>2^{\circ}>1^{\circ}\).#

10

Identify the mechanisms with the given reactivity order of haloalkanes

In the SN1 and E1 reactions, the reactivity order follows the stability of carbocation intermediates, which is \(3^{\circ}>2^{\circ}>1^{\circ}\). #j) Answer: SN1 and E1 #k) Order of reactivity of haloalkanes is methyl \(>1^{\circ}>2^{\circ}>3^{\circ}\).#

11

Identify the mechanisms with the given reactivity order of haloalkanes

In the SN2 and E2 reactions, the reactivity order is methyl \(>1^{\circ}>2^{\circ}>3^{\circ}\) because the steric hindrance decreases in that order, making it easier for the nucleophile/base to attack. #k) Answer: SN2 and E2

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