Question

Question: Pick the reactant or solvent in each part that gives the faster S_N2 reaction.

1. reaction of with OH^- or CH₃CH₂Br
2. reaction of CH₃CH₂CH₂Cl NaOH or NaOCOCH₃
3. reaction of CH₃CH₂CH₂I with ^-OCH₃ in or DMSO

Short answer

Answer

1. The reaction of OH^-with CH₃CH₂Br is faster as compared to the reaction between OH^-andCH₃CH₂Cl .
2. The reaction of CH₃CH₂CH₂Cl with NaOH is faster.
3. The reaction of CH₃CH₂CH₂I with ^-OCH₃ by using DMSO as a solvent will be faster.

Step-by-step solution

Factors affecting the SN2 reactions

The mechanism of the S_N2reactions depends upon the following factors:

• The presence of strong nucleophiles favors the S_N2mechanism.
• The use of a polar aprotic solvent also favors the S_N2reactions.
• A better leaving group also increases the rate of a S_N2reaction.
• The presence of a strong nucleophile also favors the S_N2 reaction.

This is because the presence of a strong nucleophile will result in the formation of the transition state quickly. The rate of the reaction also depends upon the concentration of the nucleophile.

The faster SN2  reactions among the reactions are as follows:

a. The reaction of OH^-with CH₃CH₂Br is faster as compared to the reaction between OH^- and CH₃CH₂Cl .

This Br^- is because the is a better leaving group as compared to the Cl^- ion.

b. The reaction of CH₃CH₂CH₂Cl with NaOH is faster. The NaOH will produce OH^- which is a stronger nucleophile as compared to OCOCH₃.

c.The reaction of CH₃CH₂CH₂I with ^-OCH₃by using DMSO as a solvent will be faster.

DMSO refers to dimethyl sulfoxide has a chemical formula of (CH₃)₂SO . It is a polar aprotic solvent. The rate of S_N2 the reaction increases by using the aprotic solvent.

On the other hand, methanol (CH₃OH) is a polar protic solvent and is unfavorable for the reactions.