Chapter 15.SE, Problem 23AP

Propose structures for aromatic hydrocarbons that meet the following descriptions:

(a) C₉H₁₂; gives only one C₉H₁₁Br product on substitution of a hydrogen on the aromatic ring with bromine

(b) C₁₀H₁₄; gives only one C₁₀H₁₃Cl product on substitution of a hydrogen on the aromatic ring with chlorine

(c) C₈H₁₀; gives three C₈H₉Br products on substitution of a hydrogen on the aromatic ring with bromine

(d) C₁₀H₁₄; gives two C₁₀H₁₃Cl products on substitution of a hydrogen on the aromatic ring with chlorine

Interpretation Introduction

a) C₉H₁₂; gives only one C₉H₁₁Br product on substitution of a hydrogen on the aromatic ring with bromine

Interpretation:

A possible structure for the hydrocarbon with molecular formula C₉H₁₂ that gives only one monobromination product C₉H₁₁Br on substitution of a hydrogen on the aromatic ring with bromine is to be given.

Concept introduction:

All aromatic compounds are derivatives of benzene. The benzene ring accounts for six carbon atoms. The remaining carbons can be attached as alkyl group like methyl, ethyl etc. to the benzene ring.

To propose:

A possible structure for the hydrocarbon with molecular formula C₉H₁₂ that gives only one monobromination product C₉H₁₁Br on substitution of a hydrogen on the aromatic ring with bromine.

Answer to Problem 23AP

A possible structure for the hydrocarbon with molecular formula C₉H₁₂ that gives only one monobromination product C₉H₁₁Br on substitution of a hydrogen atom on the aromatic ring with bromine is

Explanation of Solution

The molecular formula of the compound is C₉H₁₂. Benzene ring accounts for six carbons. When the three carbons remaining are arranged as three methyl groups alternatively on the benzene ring the three hydrogens on the other three carbons become equivalent. Hence upon bromination, the hydrocarbon gives only one monosubstituted product.

Conclusion

A possible structure for the hydrocarbon with molecular formula C₉H₁₂ that gives only one monobromination product C₉H₁₁Br on substitution of a hydrogen atom on the aromatic ring with bromine is

Interpretation Introduction

b) C₁₀H₁₄; gives only one C₁₀H₁₃Cl product on substitution of a hydrogen on the aromatic ring with chlorine

Interpretation:

A possible structure for the hydrocarbon with molecular formula C₁₀H₁₄ that gives only one monochlorination product C₁₀H₁₃Cl on substitution of a hydrogen on the aromatic ring with chlorine is to be given.

Concept introduction:

All aromatic compounds are derivatives of benzene. The benzene ring accounts for six carbon atoms. The remaining carbons can be attached as alkyl group like methyl, ethyl etc. to the benzene ring. Only one monosubstituted product will be obtained only if all the hydrogen atoms in the aromatic ring are equivalent.

To propose:

A possible structure for the hydrocarbon with molecular formula C₁₀H₁₄ that gives only one monochlorination product C₁₀H₁₃Cl on substitution of a hydrogen on the aromatic ring with chlorine is to be given.

Answer to Problem 23AP

A possible structure for the hydrocarbon with molecular formula C₁₀H₁₄ that gives only one monochlorination product, C₁₀H₁₃Cl, on substitution of a hydrogen atom on the aromatic ring with chlorine is

Explanation of Solution

The molecular formula of the hydrocarbon is C₁₀H₁₄. Benzene ring accounts for six carbons. The remaining four carbons can be arranged as four methyl groups or as two ethyl groups on the benzene ring in four different ways as shown such that remaining hydrogen atoms become equivalent. Hence upon chlorination, the hydrocarbon will give only one monosubstituted product.

Conclusion

A possible structure for the hydrocarbon with molecular formula C₁₀H₁₄ that gives only one monochlorination product, C₁₀H₁₄Cl, on substitution of a hydrogen atom on the aromatic ring with chlorine is

Interpretation Introduction

c) C₈H₁₀; gives three C₈H₉Br products on substitution of a hydrogen on the aromatic ring with bromine

Interpretation:

A possible structure for the hydrocarbon with molecular formula C₈H₁₀ that gives three monobromination products. C₈H₉Br, on substitution of a hydrogen on the aromatic ring with bromine is to be given.

Concept introduction:

All aromatic compounds are derivatives of benzene. The benzene ring accounts for six carbon atoms. The remaining carbons can be attached as alkyl group like methyl, ethyl etc. to the benzene ring.

To propose:

A possible structure for the hydrocarbon with molecular formula C₈H₁₀ that gives three products, C₈H₉Br, on substitution of a hydrogen on the aromatic ring with bromine.

Answer to Problem 23AP

A possible structure for the hydrocarbon with molecular formula C₈H₁₀ that gives three monobromination products C₉H₁₁Br on substitution of a hydrogen atom on the aromatic ring with bromine is

Explanation of Solution

The molecular formula of the hydrocarbon is C₈H₁₀. Benzene ring accounts for six carbons. When the two carbons remaining are arranged as two methyl groups meta to each other or as an ethyl group on the benzene ring hydrogens on the other carbon atoms in the ring classify themselves into three different groups. Hence upon bromination, the hydrocarbon gives three monosubstituted products.

Conclusion

A possible structure for the hydrocarbon with molecular formula C₈H₁₀ that gives three monobromination products, C₉H₁₁Br, on substitution of a hydrogen atom on the aromatic ring with bromine is

Interpretation Introduction

d) C₁₀H₁₄; gives two C₁₀H₁₃Cl products on substitution of a hydrogen atom on the aromatic ring with chlorine

Interpretation:

A possible structure for the hydrocarbon with molecular formula C₁₀H₁₄ that gives two monochlorination products C₁₀H₁₃Cl on substitution of a hydrogen atom on the aromatic ring with chlorine is to be given.

Concept introduction:

All aromatic compounds are derivatives of benzene. The benzene ring accounts for six carbon atoms. The remaining carbons can be attached as alkyl group like methyl, ethyl etc. to the benzene ring.

To propose:

A possible structure for the hydrocarbon with molecular formula C₁₀H₁₄ that gives two products, C₁₀H₁₃Cl, on substitution of a hydrogen on the aromatic ring with chlorine.

Answer to Problem 23AP

Possible structure for the hydrocarbon with molecular formula C₁₀H₁₀ that gives two monobromination products, C₁₀H₁₃Cl, on substitution of a hydrogen atom on the aromatic ring with chlorine is

Explanation of Solution

The molecular formula of the compound is C₁₀H₁₄. Benzene ring accounts for six carbons. The four carbons remaining can be arranged as two ethyl groups or as an ethyl & two methyl groups or as propyl & methyl groups or as isopropyl & methyl groups on the benzene ring as shown so that the hydrogens on the other carbon atoms in the ring classify themselves into two different groups. Hence upon chlorination, the hydrocarbon gives two monosubstituted products.

Conclusion

A possible structure for the hydrocarbon with molecular formula C₁₀H₁₀ that gives two monobromination products, C₁₀H₁₃Cl, on substitution of a hydrogen atom on the aromatic ring with chlorine is