Chapter 19, Problem 1Q

Interpretation Introduction

Interpretation:

The reason for 2-bromobutane to react faster than 2-chlorobutane in the test ofsilver nitrate with ethanol and $\text{NaI}$ with acetone needs to be explained.

Concept Introduction:

Alkyl halides have halogen group as the functional group which can substitute with other groups to give substitutional reactions. In the nucleophilic substitution reactions, the reactivities of the alkyl halides depends on two important factors such as reaction conditions and substrate structure.

Answer to Problem 1Q

In 2-bromobutane, -Br is a better leaving group than −Cl therefore it reacts faster than 2-chlorobutane.

Explanation of Solution

Given information:

Both 2-bromobutane and 2-chlorobutane give positive test with silver nitrate with ethanol and KI with acetone.

In 2-bromobutane, -Br is a better leaving group than −Cl therefore it reacts faster than 2-chlorobutane. The −Br leaving group is a weak base therefore it is a good leaving group compare to −Cl which is a stronger base and weak leaving group.

Hence 2-bromobutane reacts faster than 2-chlorobutane with silver nitrate with ethanol and $\text{NaI}$ with acetone as both are substitution reactions that replace −Cl and −Br with −I and ${\text{–NO}}_{\text{3}}$.

Conclusion

In 2-bromobutane, -Br is a better leaving group than −Cl therefore it reacts faster than 2-chlorobutane.