Chapter 9, Problem 9.48P

What alkenes are formed when each alcohol is dehydrated with $\text{TsOH}$? Label the major product when a mixture

results.

a. b. c. d. ${\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}\text{OH}$ e.

Interpretation Introduction

(a)

Interpretation: The alkenes formed by the treatment of given alcohol with $\text{TsOH}$ are to be stated and the major product is to be labeled if a mixture results.

Concept introduction: Alcohols undergo dehydration reaction in the presence of strong acids like ${\text{H}}_{\text{2}}{\text{SO}}_{\text{4}}$ or $\text{p-toluenesulfonic}\text{acid}\left(\text{TsOH}\right)$ and yield alkenes. The more substituted alcohols dehydrate rapidly. If an alcohol contains two or more $\text{β}$ carbon, then dehydration is regioselective and the major product is determined by Zaitsev rule. According to this rule, the major product is more substituted alkene, when an alcohol contains two or more $\mathrm{\beta }$ carbons.

Answer to Problem 9.48P

The alkenes formed by the treatment of given alcohol with $\text{TsOH}$ (major product is labeled) are shown below:

Explanation of Solution

The given alcohol contains two $\text{β}$ carbons.

Alcohols undergo dehydration reaction in the presence of strong acids like ${\text{H}}_{\text{2}}{\text{SO}}_{\text{4}}$ or $\text{p-toluenesulfonic}\text{acid}\left(\text{TsOH}\right)$ and yield alkenes. The more substituted alcohols dehydrate rapidly. If an alcohol contains two or more $\text{β}$ carbon, then dehydration is regioselective and the major product is determined by Zaitsev rule. According to this rule, the major product is more substituted alkene, when an alcohol contains two or more $\text{β}$ carbons.

Thus, the alkenes formed by the treatment of given alcohol with $\text{TsOH}$ (major product is labeled) are,

Figure 1

Conclusion

The alkenes formed by the treatment of given alcohol with $\text{TsOH}$ (major product is labeled) are shown in Figure 1.

Interpretation Introduction

(b)

Interpretation: The alkenes formed by the treatment of given alcohol with $\text{TsOH}$ are to be stated and the major product is to be labeled if a mixture results.

Concept introduction: Alcohols undergo dehydration reaction in the presence of strong acids like ${\text{H}}_{\text{2}}{\text{SO}}_{\text{4}}$ or $\text{p-toluenesulfonic}\text{acid}\left(\text{TsOH}\right)$ and yield alkenes. The more substituted alcohols dehydrate rapidly. If an alcohol contains two or more $\text{β}$ carbon, then dehydration is regioselective and the major product is determined by Zaitsev rule. According to this rule, the major product is more substituted alkene, when an alcohol contains two or more $\text{β}$ carbons.

Answer to Problem 9.48P

The alkenes formed by the treatment of given alcohol with $\text{TsOH}$ (major product is labeled) are shown below:

Explanation of Solution

The given alcohol contains two $\text{β}$ carbons.

Alcohols undergo dehydration reaction in the presence of strong acids like ${\text{H}}_{\text{2}}{\text{SO}}_{\text{4}}$ or $\text{p-toluenesulfonic}\text{acid}\left(\text{TsOH}\right)$ and yield alkenes. The more substituted alcohols dehydrate rapidly. If an alcohol contains two or more $\text{β}$ carbon, then dehydration is regioselective and the major product is determined by Zaitsev rule. According to this rule, the major product is more substituted alkene, when an alcohol contains two or more $\text{β}$ carbons.

Thus, the alkenes formed by the treatment of given alcohol with $\text{TsOH}$ (major product is labeled) are,

Figure 2

Conclusion

The alkenes formed by the treatment of given alcohol with $\text{TsOH}$ (major product is labeled) are shown in Figure 2.

Interpretation Introduction

(c)

Interpretation: The alkenes formed by the treatment of given alcohol with $\text{TsOH}$ are to be stated and the major product is to be labeled if a mixture results.

Concept introduction: Alcohols undergo dehydration reaction in the presence of strong acids like ${\text{H}}_{\text{2}}{\text{SO}}_{\text{4}}$ or $\text{p-toluenesulfonic}\text{acid}\left(\text{TsOH}\right)$ and yield alkenes. The more substituted alcohols dehydrate rapidly. If an alcohol contains two or more $\text{β}$ carbon, then dehydration is regioselective and the major product is determined by Zaitsev rule. According to this rule, the major product is more substituted alkene, when an alcohol contains two or more $\text{β}$ carbons.

Answer to Problem 9.48P

The alkenes formed by the treatment of given alcohol with $\text{TsOH}$ (major product is labeled) are shown below:

Explanation of Solution

The given alcohol contains three $\text{β}$ carbons.

Alcohols undergo dehydration reaction in the presence of strong acids like ${\text{H}}_{\text{2}}{\text{SO}}_{\text{4}}$ or $\text{p-toluenesulfonic}\text{acid}\left(\text{TsOH}\right)$ and yield alkenes. The more substituted alcohols dehydrate rapidly. If an alcohol contains two or more $\text{β}$ carbon, then dehydration is regioselective and the major product is determined by Zaitsev rule. According to this rule, the major product is more substituted alkene, when an alcohol contains two or more $\text{β}$ carbons.

Thus, the alkenes formed by the treatment of given alcohol with $\text{TsOH}$ (major product is labeled) are,

Figure 3

Conclusion

The alkenes formed by the treatment of given alcohol with $\text{TsOH}$ (major product is labeled) are shown in Figure 3.

Interpretation Introduction

(d)

Interpretation: The alkenes formed by the treatment of given alcohol with $\text{TsOH}$ are to be stated and the major product is to be labeled if a mixture results.

Concept introduction: Alcohols undergo dehydration reaction in the presence of strong acids like ${\text{H}}_{\text{2}}{\text{SO}}_{\text{4}}$ or $\text{p-toluenesulfonic}\text{acid}\left(\text{TsOH}\right)$ and yield alkenes. The more substituted alcohols dehydrate rapidly. If an alcohol contains two or more $\text{β}$ carbon, then dehydration is regioselective and the major product is determined by Zaitsev rule. According to this rule, the major product is more substituted alkene, when an alcohol contains two or more $\text{β}$ carbons.

Answer to Problem 9.48P

The alkene formed by the treatment of given alcohol with $\text{TsOH}$ (major product is labeled) is ${\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}\text{CH}={\text{CH}}_{\text{2}}$.

Explanation of Solution

The given alcohol contains two $\text{β}$ carbons.

Alcohols undergo dehydration reaction in the presence of strong acids like ${\text{H}}_{\text{2}}{\text{SO}}_{\text{4}}$ or $\text{p-toluenesulfonic}\text{acid}\left(\text{TsOH}\right)$ and yield alkenes. The more substituted alcohols dehydrate rapidly. The given alcohol is primary. It undergoes protonation followed by elimination to form alkene. The alkene formed by the treatment of given alcohol with $\text{TsOH}$ (major product is labeled) is shown in the reaction given below.

${\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{CH}}_2{\text{CH}}_{\text{2}}\text{OH}\stackrel{\text{TsOH}}{\to }{\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}\text{CH}={\text{CH}}_{\text{2}}$

Conclusion

The alkenes formed by the treatment of given alcohol with $\text{TsOH}$ (major product is labeled) are shown in Figure 4.

Interpretation Introduction

(e)

Interpretation: The alkenes formed by the treatment of given alcohol with $\text{TsOH}$ are to be stated and the major product is to be labeled if a mixture results.

Concept introduction: Alcohols undergo dehydration reaction in the presence of strong acids like ${\text{H}}_{\text{2}}{\text{SO}}_{\text{4}}$ or $\text{p-toluenesulfonic}\text{acid}\left(\text{TsOH}\right)$ and yield alkenes. The more substituted alcohols dehydrate rapidly. If an alcohol contains two or more $\text{β}$ carbon, then dehydration is regioselective and the major product is determined by Zaitsev rule. According to this rule, the major product is more substituted alkene, when an alcohol contains two or more $\text{β}$ carbons.

Answer to Problem 9.48P

The alkenes formed by the treatment of given alcohol with $\text{TsOH}$ (major product is labeled) are shown below:

Explanation of Solution

The given alcohol contains two $\text{β}$ carbons.

Alcohols undergo dehydration reaction in the presence of strong acids like ${\text{H}}_{\text{2}}{\text{SO}}_{\text{4}}$ or $\text{p-toluenesulfonic}\text{acid}\left(\text{TsOH}\right)$ and yield alkenes. The more substituted alcohols dehydrate rapidly. If an alcohol contains two or more $\text{β}$ carbon, then dehydration is regioselective and the major product is determined by Zaitsev rule. According to this rule, the major product is more substituted alkene, when an alcohol contains two or more $\text{β}$ carbons.

Thus, the alkenes formed by the treatment of given alcohol with $\text{TsOH}$ (major product is labeled) are,

Figure 4

Conclusion

The alkenes formed by the treatment of given alcohol with $\text{TsOH}$ (major product is labeled) are shown in Figure 4.