Chapter 23, Problem 23.50P

Interpretation Introduction

(a)

Interpretation:

Whether fuming sulfuric acid should be added to concentrated sulfuric acid to carry out sulfonation on the given compound is to be determined.

Concept introduction:

Sulfonation is the electrophilic aromatic substitution reaction. The aromatic ring, on reaction with concentrated sulfuric acid or fuming sulfuric acid (${\text{H}}_{\text{2}}{\text{SO}}_{\text{4}}$ enriched with ${\text{SO}}_{\text{3}}$), undergoes substitution of one of the ring hydrogen by ${\text{SO}}_{\text{3}}\text{H}$ group and forms aryl sulfonic acid ; this is called sulfonation. The selection of reagent concentrated sulfuric acid or fuming sulfuric acid depends on whether the aromatic ring is activated or deactivated. The electron donating groups increase the electron density around the ring and activate it whereas the electron withdrawing groups decrease the electron density around the ring and deactivate it. The activated aromatic ring can undergo sulfonation on reaction with concentrated sulfuric acid. The deactivated ring requires the addition of fuming sulfuric acid to concentrated sulfuric acid to undergo sulfonation.

Answer to Problem 23.50P

Fuming sulfuric acid should not be added to concentrated sulfuric acid to carry out sulfonation on the given compound as the aromatic ring is activated.

Explanation of Solution

The given aromatic compound is:

In this aromatic compound, the benzene ring has two methyl groups attached. The alkyl groups are electron inductively donating and activate the ring. The ring can then undergo sulfonation on reaction with concentrated sulfuric acid, and there is no need to add fuming sulfuric acid.

Conclusion

It is determined that sulfonation of the given compound can be carried out with concentrated sulfuric acid only and no need to add fuming sulfuric acid based on the activation of the aromatic ring.

Interpretation Introduction

(b)

Interpretation:

Whether fuming sulfuric acid should be added to concentrated sulfuric acid to carry out sulfonation on the given compound is to be determined.

Concept introduction:

Sulfonation is an electrophilic aromatic substitution reaction. The aromatic ring, on reaction with sulfuric acid or with a mixture of concentrated sulfuric acid and sulfuric acid, undergoes substitution of one of the ring hydrogen by nitro group and forms nitrobenzene; this is called sulfonation. The selection of reagent either sulfuric acid or mixture of sulfuric acid and sulfuric acid depends on whether the aromatic ring is activated or deactivated. The electron donating groups increase the electron density around the ring and activate it whereas the electron withdrawing groups decrease the electron density around the ring and deactivate it. The activated aromatic ring can undergo sulfonation on reaction with sulfuric acid. The deactivated ring requires the addition of sulfuric acid to sulfuric acid to undergo sulfonation.

Answer to Problem 23.50P

Fuming sulfuric acid should be added to concentrated sulfuric acid to carry out sulfonation on the given compound as the aromatic ring is deactivated.

Explanation of Solution

The given aromatic compound is:

In this aromatic compound, the benzene ring has two carbonyl groups attached. The carbonyl groups have electron withdrawing resonance effect, thus decreasing the electron density around the ring and deactivating it. As the ring is electron poor and deactivated, fuming sulfuric acid should be added to concentrated sulfuric acid to carry out sulfonation.

Conclusion

It is determined that sulfonation of the given compound can be carried by addition of sulfuric acid to concentrated sulfuric acid based on deactivation of the aromatic ring.

Interpretation Introduction

(c)

Interpretation:

Whether fuming sulfuric acid should be added to concentrated sulfuric acid to carry out sulfonation on the given compound is to be determined.

Concept introduction:

Sulfonation is the electrophilic aromatic substitution reaction. The aromatic ring on reaction with sulfuric acid or with a mixture of concentrated sulfuric acid and sulfuric acid undergoes substitution of one of the ring hydrogen by nitro group and forms nitrobenzene; this is called sulfonation. The selection of reagent either sulfuric acid or mixture of sulfuric acid and sulfuric acid depends on whether the aromatic ring is activated or deactivated. The electron donating groups increase the electron density around the ring and activate it whereas the electron withdrawing groups decrease the electron density around the ring and deactivate it. The activated aromatic ring can undergo sulfonation on reaction with sulfuric acid. The deactivated ring requires the addition of sulfuric acid to sulfuric acid to undergo sulfonation.

Answer to Problem 23.50P

Fuming sulfuric acid should be added to concentrated sulfuric acid to carry out sulfonation on the given compound as the aromatic ring is deactivated.

Explanation of Solution

The given aromatic compound is:

In this aromatic compound, the benzene ring has a nitrile group attached. The nitrile group has electron withdrawing resonance effect, thus decreasing the electron density around the ring and deactivating it. As the ring is electron poor and deactivated, fuming sulfuric acid should be added to concentrated sulfuric acid to carry out sulfonation.

Conclusion

It is determined that sulfonation of a given compound can be carried by addition of sulfuric acid to concentrated sulfuric acid based on deactivation of aromatic ring.

Interpretation Introduction

(d)

Interpretation:

Whether fuming sulfuric acid should be added to concentrated sulfuric acid to carry out sulfonation on the given compound is to be determined.

Concept introduction:

Sulfonation is the electrophilic aromatic substitution reaction. The aromatic ring on reaction with sulfuric acid or with a mixture of concentrated sulfuric acid and sulfuric acid undergoes substitution of one of the ring hydrogen by nitro group and forms nitrobenzene; this is called sulfonation. The selection of reagent either sulfuric acid or mixture of sulfuric acid and sulfuric acid depends on whether the aromatic ring is activated or deactivated. The electron donating groups increases the electron density around the ring and activates it whereas the electron withdrawing groups decrease the electron density around the ring and deactivate it. The activated aromatic ring can undergo sulfonation on reaction with sulfuric acid. The deactivated ring requires the addition of sulfuric acid to sulfuric acid to undergo sulfonation. The resonance effect is predominant over inductive effect due to actual delocalization of pi electrons.

Answer to Problem 23.50P

Fuming sulfuric acid should be added to concentrated sulfuric acid to carry out sulfonation on the given compound as the aromatic ring is deactivated.

Explanation of Solution

The given aromatic compound is:

In this aromatic compound, the benzene ring has ${\text{SO}}_{\text{3}}\text{H}$ group and methyl group attached. ${\text{SO}}_{\text{3}}\text{H}$ group has electron withdrawing resonance effect, and the methyl has electron donating inductive effect. The resonance effect is predominant over inductive effect thus decreasing the electron density around the ring and strongly deactivating it. As the ring is electron poor and deactivated, the sulfuric acid should be added to sulfuric acid to carry out sulfonation.

Conclusion

It is determined that sulfonation of a given compound can be carried by addition of sulfuric acid to concentrated sulfuric acid based on deactivation of aromatic ring.

Interpretation Introduction

(e)

Interpretation:

Whether fuming sulfuric acid should be added to concentrated sulfuric acid to carry out sulfonation on the given compound is to be determined.

Concept introduction:

Sulfonation is the electrophilic aromatic substitution reaction. The aromatic ring on reaction with sulfuric acid or with a mixture of concentrated sulfuric acid and sulfuric acid undergoes substitution of one of the ring hydrogen by nitro group and forms nitrobenzene; this is called sulfonation. The selection of reagent either sulfuric acid or mixture of sulfuric acid and sulfuric acid is depends on whether the aromatic ring is activated or deactivated. The electron donating groups increase the electron density around the ring and activate it whereas the electron withdrawing groups decrease the electron density around the ring and deactivate it. The activated aromatic ring can undergo sulfonation on reaction with sulfuric acid. The deactivated ring requires the addition of sulfuric acid to sulfuric acid to undergo sulfonation.

Answer to Problem 23.50P

Fuming sulfuric acid should be added to concentrated sulfuric acid to carry out sulfonation on the given compound as the aromatic ring is deactivated.

Explanation of Solution

The given aromatic compound is:

In this aromatic compound, the benzene ring has ${\text{SO}}_{\text{3}}\text{H}$ group and chlorine attached. Both ${\text{SO}}_{\text{3}}\text{H}$ groups have electron withdrawing resonance effect, and chlorine has electron withdrawing inductive effect, thus decreasing the electron density around the ring and strongly deactivating it. As the ring is electron poor and deactivated, the sulfuric acid should be added to sulfuric acid to carry out sulfonation.

Conclusion

It is determined that the sulfonation of a given compound can be carried out by the addition of sulfuric acid to concentrated sulfuric acid based on deactivation of aromatic ring.

Interpretation Introduction

(f)

Interpretation:

Whether fuming sulfuric acid should be added to concentrated sulfuric acid to carry out sulfonation on the given compound is to be determined.

Concept introduction:

The sulfonation is the electrophilic aromatic substitution reaction. The aromatic ring on reaction with sulfuric acid or with a mixture of concentrated sulfuric acid and sulfuric acid undergoes substitution of one of the ring hydrogen by nitro group and forms nitrobenzene; this is called sulfonation. The selection of reagent either sulfuric acid or mixture of sulfuric acid and sulfuric acid is depends on whether the aromatic ring is activated or deactivated. The electron donating groups increase the electron density around the ring and activate it whereas the electron withdrawing groups decrease the electron density around the ring and deactivate it. The activated aromatic ring can undergo sulfonation on reaction with sulfuric acid. The deactivated ring requires the addition of sulfuric acid to sulfuric acid to undergo sulfonation.

Answer to Problem 23.50P

The fuming sulfuric acid should not be added to concentrated sulfuric acid to carry out a sulfonation on given compound as the aromatic ring is activated.

Explanation of Solution

The given aromatic compound is:

In this aromatic compound, the benzene ring has one methyl and one methoxy group attached. The alkyl groups are electron donating inductively, and methoxy group has electron donating resonance effect, thus increasing the electron density around the ring and activating it. As the ring is electron rich and activated, it can undergo sulfonation on reaction with concentrated sulfuric acid, and there is no need to add sulfuric acid.

Conclusion

It is determined that the sulfonation of a given compound can be carried out with concentrated sulfuric acid only and no need to add fuming sulfuric acid based on the activation of aromatic ring.