Chapter 7, Problem 7.38P

Interpretation Introduction

(a)

Interpretation:

It is to be explained why the heterolysis step on the left does not occur readily than the one on the right.

Concept introduction:

Heterolysis is an elementary step in which a single bond is broken, and both the electrons from that bond end up on one of the atoms initially involved in the bond. In this step, when the bond breaks, the bonding pair of electrons gets distributed unequally. This results in the formation of a positively charged species and a negatively charged species. The alkyl groups attached to positively charged species stabilizes the positive charge. The increasing order for the stability of carbocations is: $\text{methyl < primary < secondary < tertiary}$. As the number of alkyl groups attached to the carbon bearing a positive charge increases, the stability of a carbocation increases.

Driving force is responsible for the elementary step to go to completion. The driving force for a reaction is the extent to which the reaction favors products over reactants, and that tendency increases with increasing stability of the products relative to the reactants. Charge stability and total bond energy are two major factors that contribute to a reaction’s driving force. The amount of energy required to break a bond is termed as bond energy.

Interpretation Introduction

(b)

Interpretation:

It is to be explained why the heterolysis step on the left does not occur readily than the one on the right.

Concept introduction:

Heterolysis is an elementary step in which a single bond is broken, and both the electrons from that bond end up on one of the atoms initially involved in the bond. In this step, when the bond breaks, the bonding pair of electrons gets distributed unequally. This results in the formation of a positively charged species and a negatively charged species. The alkyl groups attached to positively charged species stabilizes the positive charge. The increasing order for the stability of carbocations is: $\text{methyl < primary < secondary < benzylic < tertiary}$. As the number of alkyl groups attached to the carbon bearing a positive charge increases, the stability of a carbocation increases.

Driving force is responsible for an elementary step to go to completion. The driving force for a reaction is the extent to which the reaction favors products over reactants, and that tendency increases with increasing stability of the products relative to the reactants. Charge stability and total bond energy are two major factors that contribute to a reaction’s driving force. The amount of energy required to break a bond is termed as bond energy.

Interpretation Introduction

(c)

Interpretation:

It is to be explained why the heterolysis step on the left does not occur readily than the one on the right.

Concept introduction:

Heterolysis is an elementary step in which a single bond is broken and both the electrons from that bond end up on one of the atoms initially involved in the bond. In this step, when the bond breaks, the bonding pair of electrons gets distributed unequally. This results in the formation of a positively charged species and a negatively charged species.

Polar protic solvents tend to solvate both cations and anions very strongly, whereas, polar aprotic solvent tend to solvate cations very strongly, but not anions.

Driving force is responsible for an elementary step to go to completion. The driving force for a reaction is the extent to which the reaction favors products over reactants, and that tendency increases with increasing stability of the products relative to the reactants. Charge stability and total bond energy are two major factors that contribute to a reaction’s driving force. The amount of energy required to break a bond is termed as bond energy.

Interpretation Introduction

(d)

Interpretation:

It is to be explained why the heterolysis step on the left does not occur readily than the one on the right.

Concept introduction:

Heterolysis is an elementary step in which a single bond is broken, and both the electrons from that bond end up on one of the atoms initially involved in the bond. In this step, when the bond breaks, the bonding pair of electrons gets distributed unequally. This results in the formation of a positively charged species and a negatively charged species.

During nucleophilic substitution reactions, a nucleophile forms a bond to the substrate, and at the same time, the bond to the leaving group is broken. Leaving group comes off in the form of a negatively charged species. Larger atoms accommodate the negative charge better as compared to smaller atoms. Leaving groups are typically conjugate bases of strong acids. Driving force is responsible for an elementary step to go to completion. The driving force for a reaction is the extent to which the reaction favors products over reactants, and that tendency increases with increasing stability of the products relative to the reactants. Charge stability and total bond energy are two major factors that contribute to a reaction’s driving force. The amount of energy required to break a bond is termed as bond energy.