Question

Provide at least 1 example to describe that the rate of SN₂ reactions depends on the nature of the nucleophile.

a. CH₃Cl + OH⁻

b. CH₃Cl + NH₂⁻

c. CH₃Cl + CH₃O⁻

d. CH₃Cl + Cl⁻

Answer 1

The rate of SN2 reactions varies depending on the strength of the nucleophile. Strong nucleophiles with negative charges, like OH-, NH2-, and CH3O-, react quickly and thus increase the reaction rate in an SN2 mechanism, unlike weaker nucleophiles such as Cl-.

Step-by-step explanation:

The rate of SN2 reactions depends on several factors, including the nature of the nucleophile involved in the reaction. In such reactions, good nucleophiles, which often bear a negative charge and have available lone pairs of electrons, react faster than weaker nucleophiles. Let's look at the reaction of CH3Cl with different nucleophiles:

• CH3Cl + OH-: Hydroxide ion (OH-) is a strong nucleophile, which would lead to a fast SN2 reaction rate.
• CH3Cl + NH2-: Amide ion (NH2-) is also a strong nucleophile and is expected to react quickly in the SN2 mechanism.
• CH3Cl + CH3O-: Methoxide ion (CH3O-) is a strong nucleophile which makes the reaction rate high in an SN2.
• CH3Cl + Cl-: Chloride ion (Cl-) is a weaker nucleophile compared to others listed here, hence the reaction would occur at a slower rate.

The provided examples illustrate the concept that stronger nucleophiles such as OH-, NH2-, and CH3O-, increase the rate of SN2 reactions, as they are more reactive than their neutral or less negatively charged counterparts.