Chapter 3, Problem 56IP

(a)

Interpretation Introduction

Interpretation:

Constitutional isomer is needed to be drawn for the given molecular formula ${\text{C}}_{\text{4}}{\text{H}}_8{\text{O}}_{\text{2}}$ which is lesser, higher and same $\text{pka}$ that of given constitutional isomer.

Concept introduction:

Constitutional isomers:

• Constitutional isomers are isomers which have the same molecular formula and different bond connectivity between the atoms in the molecule.

Acidic strength of the molecule depends on the stability of the Conjugate anion.

• If the conjugate anion is more resonance stabilized, the acid considered as strong acid and has less $\text{pka}$, corresponding anion is weak base. And the least stable anion has higher $\text{pka}$ value.
• If more sterically hindered the group, basic nature is more for that molecule. That means bulkiness increases the basic strength of the molecule. 

To draw: the constitutional isomers for the molecular formula ${\text{C}}_{\text{4}}{\text{H}}_8{\text{O}}_{\text{2}}$, which has higher $\text{pka}$ value than given constitutional isomer.

(b)

Interpretation Introduction

Interpretation:

Constitutional isomer is needed to be drawn for the given molecular formula ${\text{C}}_{\text{4}}{\text{H}}_8{\text{O}}_{\text{2}}$ which is lesser, higher and same $\text{pka}$ that of given constitutional isomer.

Concept introduction:

Constitutional isomers:

• Constitutional isomers are isomers which have the same molecular formula and different bond connectivity between the atoms in the molecule.

Acidic strength of the molecule depends on the stability of the Conjugate anion.

• If the conjugate anion is more resonance stabilized, the acid considered as strong acid and has less $\text{pka}$, corresponding anion is weak base. And the least stable anion has higher $\text{pka}$ value.
• If more sterically hindered the group, basic nature is more for that molecule. That means bulkiness increases the basic strength of the molecule. 

To give: the constitutional isomers for the molecular formula ${\text{C}}_{\text{4}}{\text{H}}_8{\text{O}}_{\text{2}}$, which has higher $\text{pka}$ value than given constitutional isomer.

(c)

Interpretation Introduction

Interpretation:

Constitutional isomer is needed to be drawn for the given molecular formula ${\text{C}}_{\text{4}}{\text{H}}_8{\text{O}}_{\text{2}}$ which is lesser, higher and same $\text{pka}$ that of given constitutional isomer.

Concept introduction:

Constitutional isomers:

• Constitutional isomers are isomers which have the same molecular formula and different bond connectivity between the atoms in the molecule.

Acidic strength of the molecule depends on the stability of the Conjugate anion.

• If the conjugate anion is more resonance stabilized, the acid considered as strong acid and has less $\text{pka}$, corresponding anion is weak base. And the least stable anion has higher $\text{pka}$ value.
• If more sterically hindered the group, basic nature is more for that molecule. That means bulkiness increases the basic strength of the molecule. 

To give: the constitutional isomers for the molecular formula ${\text{C}}_{\text{4}}{\text{H}}_8{\text{O}}_{\text{2}}$, which has approximately same $\text{pka}$ value of the given constitutional isomer.