Chapter 9, Problem 9.81P

Interpretation Introduction

(a)

Interpretation:

For the given reaction, the major product is to be determined. The complete, detailed mechanism is to be drawn.

Concept introduction:

When the attacking species is an alcohol which is a weak base and weak nucleophile, it favors ${\text{S}}_{\text{N}}\text{1}$ and E1 reactions. Excellent leaving group favors ${\text{S}}_{\text{N}}\text{1}$ and E1 reactions. The presence of heat favors elimination reaction over substitution reaction. The carbocation can be rearranged by $\text{1, 2-}$ hydride or $\text{1, 2-}$ methyl shift to form a more stable carbocation. The proton is eliminated from that adjacent carbon of carbocation which gives the highly substituted alkene product.

Answer to Problem 9.81P

The complete, detailed mechanism and the major product for the given reaction is shown below:

Explanation of Solution

The given reacting species are shown below:

In the given reaction, attacking species is an alcohol which is a weak nucleophile. Also, the leaving group can be water under acidic conditions which is an excellent leaving group. Also, the solvent is an alcohol. Therefore, the given reaction favors ${\text{S}}_{\text{N}}\text{1}$ and E1 reaction. The presence of heat favors elimination over substitution. Thus the reaction favors E1 reaction. The proton is eliminated from that adjacent carbon which gives the highly substituted alkene product. The complete, detailed mechanism and the major product for the given reaction is shown below:

Conclusion

The complete, detailed mechanism and the major product for the given reaction is drawn on the basis of reacting species.

Interpretation Introduction

(b)

Interpretation:

For the given reaction, the major product is to be determined. The complete, detailed mechanism is to be drawn.

Concept introduction:

When attacking species is an alcohol which is a weak base and weak nucleophile, it favors ${\text{S}}_{\text{N}}\text{1}$ and E1 reactions. Excellent leaving group favors ${\text{S}}_{\text{N}}\text{1}$ and E1 reactions. Presence of heat favors elimination reaction over substitution reaction. The proton is eliminated from that adjacent carbon of carbocation which gives the highly substituted alkene product.

Answer to Problem 9.81P

The complete, detailed mechanism and the major product for the given reaction is shown below:

Explanation of Solution

The given reacting species are shown below,

In the given reaction, attacking species is an alcohol which is a weak nucleophile. Also, the leaving group can be water under acidic conditions which is an excellent leaving group. Also, the solvent is an alcohol. Therefore, the given reaction favors ${\text{S}}_{\text{N}}\text{1}$ and E1 reaction. The presence of heat favors elimination over substitution. Thus the reaction favors E1 reaction. The proton is eliminated from that adjacent carbon which gives the highly substituted alkene product. The complete, detailed mechanism and the major product for the given reaction is shown below:

Conclusion

The complete, detailed mechanism and the major product for the given reaction are drawn on the basis of reacting species.

Interpretation Introduction

(c)

Interpretation:

For the given reaction, the major product is to be determined. The complete, detailed mechanism is to be drawn.

Concept introduction:

When attacking species is an alcohol which is a weak base and weak nucleophile, it favors ${\text{S}}_{\text{N}}\text{1}$ and E1 reactions. Excellent leaving group i.e ${\text{H}}_{\text{2}}\text{O}$ (under acidic conditions) favor ${\text{S}}_{\text{N}}\text{1}$ and E1 reactions. Presence of heat favors elimination reaction over substitution reaction. The proton is eliminated from that adjacent carbon of carbocation which gives the highly substituted alkene product.

Answer to Problem 9.81P

The complete, detailed mechanism and the major product for the given reaction is shown below:

Explanation of Solution

The given reacting species are shown below,

In the given reaction, attacking species is an alcohol which is a weak nucleophile. Also, the leaving group can be water under acidic conditions which is an excellent leaving group. Also, the solvent is an alcohol. Therefore, the given reaction favors ${\text{S}}_{\text{N}}\text{1}$ and E1 reaction. The presence of heat favors elimination over substitution. Thus the reaction favors E1 reaction. The proton is eliminated from that adjacent carbon which gives the highly substituted alkene product. The complete, detailed mechanism and the major product for the given reaction is shown below:

Conclusion

The complete, detailed mechanism and the major product for the given reaction are drawn on the basis of reacting species.

Interpretation Introduction

(d)

Interpretation:

The major product of the given reaction is to be determined. The complete, detailed mechanism is to be drawn.

Concept introduction:

When attacking species is an alcohol which is a weak base and weak nucleophile, it favors ${\text{S}}_{\text{N}}\text{1}$ and E1 reactions. Excellent leaving group favor ${\text{S}}_{\text{N}}\text{1}$ and E1 reactions. The protic solvent favors SN1 and E1 reactions. If heat is not present then substitution is favored over elimination. When the carbocation is resonance delocalized, the nucleophile can attack either carbon bearing positive charge, giving isomeric products.

Answer to Problem 9.81P

The complete, detailed mechanism and the major product for the given reaction is shown below,

Explanation of Solution

The given reacting species are shown below,

In the given reaction, attacking species is an alcohol which is a weak nucleophile. Also, the leaving group can be water under acidic conditions which is an excellent leaving group. Also, the solvent is an alcohol. Therefore, the given reaction favors ${\text{S}}_{\text{N}}\text{1}$ and E1 reaction. The presence of heat favors elimination over substitution. Thus the reaction favors E1 reaction. The proton is eliminated from that adjacent carbon which gives the highly substituted alkene product. The complete, detailed mechanism and the major product for the given reaction is shown below:

Conclusion

The complete, detailed mechanism and the major product for given reaction are drawn on the basis of reacting species.

Interpretation Introduction

(e)

Interpretation:

For the given reaction, the major product is to be determined. The complete, detailed mechanism is to be drawn.

Concept introduction:

The strong nucleophile and weak base favors ${\text{S}}_{\text{N}}\text{2}$ and E1 reaction. If the concentration of nucleophile is high, it favors ${\text{S}}_{\text{N}}\text{2}$ reaction. If the solvent is aprotic, it favors ${\text{S}}_{\text{N}}\text{2}$ and E2 reaction. An ${\text{S}}_{\text{N}}\text{2}$ reaction gives product with inversion of configuration.

Answer to Problem 9.81P

The complete, detailed mechanism and product of the given reaction is as shown below:

Explanation of Solution

The given reacting species are shown below,

The Br- is a strong nucleophile but a weak base that favors ${\text{S}}_{\text{N}}\text{2}$ and E1 reaction. The concentration of ${\text{Br}}^{\text{-}}$ is high which favors ${\text{S}}_{\text{N}}\text{2}$ reaction. The solvent DMSO is aprotic which favors ${\text{S}}_{\text{N}}\text{2}$ and E2 reactions. Therefore the given reaction favors ${\text{S}}_{\text{N}}\text{2}$ mechanism. The inversion of configuration takes place. The complete, detailed mechanism and product of the given reaction is as shown below,

Conclusion

The complete, detailed mechanism and the major product for the given reaction are drawn on the basis of reacting species.

Interpretation Introduction

(f)

Interpretation:

For the given reaction, the major product is to be determined. The complete, detailed mechanism is to be drawn.

Concept introduction:

If the attacking species is a strong bulky base but has low concentration it favors ${\text{S}}_{\text{N}}\text{1}$ and E1 mechanism. When the leaving group is excellent, it favors ${\text{S}}_{\text{N}}\text{1}$ and E1 mechanism. Protic solvent favors ${\text{S}}_{\text{N}}\text{1}$ and E1 mechanism. The absence of heat favors substitution over elimination. Both R and S configurations are formed for substitution products. Both cis and trans isomers are formed for elimination products. The carbocation can be rearranged by $\text{1, 2-}$ hydride or $\text{1, 2-}$ methyl shift to form a more stable carbocation.

Answer to Problem 9.81P

The complete, detailed mechanism and the products of the given reaction are shown below,

Explanation of Solution

The given reacting species are shown below,

In the given reaction, the attacking species is a strong bulky base so it favors ${\text{S}}_{\text{N}}2$ and E2 mechanism. But as the concentration of it is low, it favors ${\text{S}}_{\text{N}}\text{1}$ and E1 mechanism. The leaving group ${\text{TsO}}^{\text{-}}$ is excellent which favors ${\text{S}}_{\text{N}}\text{1}$ and E1 mechanism. The solvent is protic so it favors ${\text{S}}_{\text{N}}\text{1}$ and E1 mechanisms. As the heat is not given, it favors substitution over elimination. Therefore, both ${\text{S}}_{\text{N}}\text{1}$ and E1 mechanism are favored but ${\text{S}}_{\text{N}}\text{1}$ is favored more. Both R and S configurations of the product are formed in substitution reactions. The complete, detailed mechanism and the products of given reaction are shown below:

Conclusion

The complete, detailed mechanism and the major product for the given reaction is drawn on the basis of reacting species.

Interpretation Introduction

(g)

Interpretation:

For the given reaction, the major product is to be determined. The complete, detailed mechanism is to be drawn.

Concept introduction:

When attacking species is an alcohol which is a weak base and weak nucleophile, it favors ${\text{S}}_{\text{N}}\text{1}$ and E1 reactions. Excellent leaving group favors ${\text{S}}_{\text{N}}\text{1}$ and E1 reactions. The protic solvent favors SN1 and E1 reactions. Benzylic carbon favors ${\text{S}}_{\text{N}}\text{1}$ and E1 reactions. If heat is not present then substitution is favored over elimination. When the carbocation is resonance delocalized, the nucleophile can attack either carbon bearing positive charge giving isomeric products. This type of substitution gives recemic mixture of products.

Answer to Problem 9.81P

The complete, detailed mechanism and the major product for the given reaction is shown below,

Explanation of Solution

The given reacting species are shown below:

In the given reaction, attacking species is a weak nucleophile and weak base. Also, the leaving group ${\text{TsO}}^{\text{-}}$ is an excellent leaving group. Also, the solvent is an alcohol i.e. protic solvent. Therefore, the given reaction favors ${\text{S}}_{\text{N}}\text{1}$ and E1 reaction. The heat is not given so favors substitution over elimination. Thus the reaction favors ${\text{S}}_{\text{N}}\text{1}$ reaction. The carbocation is resonance delocalized so nucleophile can attack either carbon having positive charge. The reaction gives recemic products. The complete, detailed mechanism and the major product for the given reaction is shown below:

Conclusion

The complete, detailed mechanism and the major product for the given reaction are drawn on the basis of reacting species.