Chapter 6, Problem 6.18P

(a)

Interpretation Introduction

Interpretation:

The structure for alkene required to produce the given alcohol via acid-catalyzed hydration has to be identified.

Concept Introduction:

Acid-catalyzed hydration: It is addition of water to unsaturated bonds. In presence of strong acid such as ${\text{H}}_{\text{2}}{\text{SO}}_{\text{4}}$, alkene reacts with water to form the corresponding alcohol.

Leaving group: it is the fragment that leaves the substrate in a chemical reaction with a pair of electrons.

Nucleophile: donates pair of electrons to positively charged substrate resulting in the formation of chemical bond.

Carbocation: carbon ion that bears a positive charge on it.

Carbocation stability order:

Resonance stabilization: Due to the delocalization of electrons within the molecule the overall energy becomes lower and makes that molecule more stable.

Explanation of Solution

1. 1. The given product is $3-$ hexanol. It shows that the initial required alkene should contain 6 carbon atoms and 1 $\text{C=C}$ bond with it.
2. 2. First is ${\text{H}}^{\text{+}}$ from ${\text{H}}_{\text{3}}{O}^{+}$ attacks either of carbon present in $\text{C=C}$ since the molecule is symmetrical and both carbon are secondary. This leads to form secondary carbo cation intermediate.
3. 3. Then, lone pair of electrons from oxygen present in water attack the carbocation and form intermediate B.
4. 4. Finally, the hydrogen present in oxonium ion (oxygen with positive charge) of B gets removed in presence of water that results to form the given hexanol.

(b)

Interpretation Introduction

Interpretation:

The structure for alkene required to produce the given alcohol via acid-catalyzed hydration has to be identified.

Concept Introduction:

Acid-catalyzed hydration: It is addition of water to unsaturated bonds. In presence of strong acid such as ${\text{H}}_{\text{2}}{\text{SO}}_{\text{4}}$, alkene reacts with water to form the corresponding alcohol.

Leaving group: it is the fragment that leaves the substrate in a chemical reaction with a pair of electrons.

Nucleophile: donates pair of electrons to positively charged substrate resulting in the formation of chemical bond.

Carbocation: carbon ion that bears a positive charge on it.

Carbocation stability order:

Resonance stabilization: Due to the delocalization of electrons within the molecule the overall energy becomes lower and makes that molecule more stable.

Explanation of Solution

1. 1. The given product is $1-$ Methylcyclobutanol. It shows that the initial required alkene should contain 1 cyclobutene with one methyl group substituted at first positon.
2. 2. In the first alkene, ${\text{H}}^{\text{+}}$ from ${\text{H}}_{\text{3}}{O}^{+}$ attacks, carbon with two hydrogens present in $\text{C=C}$ to form tertiary carbo cation intermediate.
3. 3. Then, lone pair of electrons from oxygen present in water attack the carbocation and forms compound with oxonium ion.
4. 4. Finally, the hydrogen present in oxonium ion (oxygen with positive charge) gets removed in presence of water that results to form the given product.
5. 5. Similarly, in second alkene the ${\text{H}}^{\text{+}}$ from ${\text{H}}_{\text{3}}{O}^{+}$ attacks, carbon that does not contain methyl substitution and form tertiary carbocation which then in presence of water forms oxonium ion. Finally, the hydrogen present in oxonium ion (oxygen with positive charge) gets removed in presence of water that results to form the given product.

(c)

Interpretation Introduction

Interpretation:

The structure for alkene required to produce the given alcohol via acid-catalyzed hydration has to be identified.

Concept Introduction:

Acid-catalyzed hydration: It is addition of water to unsaturated bonds. In presence of strong acid such as ${\text{H}}_{\text{2}}{\text{SO}}_{\text{4}}$, alkene reacts with water to form the corresponding alcohol.

Leaving group: it is the fragment that leaves the substrate in a chemical reaction with a pair of electrons.

Nucleophile: donates pair of electrons to positively charged substrate resulting in the formation of chemical bond.

Carbocation: carbon ion that bears a positive charge on it.

Carbocation stability order:

Resonance stabilization: Due to the delocalization of electrons within the molecule the overall energy becomes lower and makes that molecule more stable.

Explanation of Solution

1. 1. The given product is $2-$ Methyl-2-butanol. It shows that the initial required alkene should contain 4 carbons in which one alcohol and one methyl groups are substituted at second carbon position.
2. 2. In the first alkene, ${\text{H}}^{\text{+}}$ from ${\text{H}}_{\text{3}}{O}^{+}$ attacks, carbon with two hydrogens present in $\text{C=C}$ to form tertiary carbo cation intermediate.
3. 3. Then, lone pair of electrons from oxygen present in water attack the carbocation and forms compound with oxonium ion.
4. 4. Finally, the hydrogen present in oxonium ion (oxygen with positive charge) gets removed in presence of water that results to form the given product.
5. 5. Similarly, in second alkene the ${\text{H}}^{\text{+}}$ from ${\text{H}}_{\text{3}}{O}^{+}$ attacks, carbon with one hydrogen atom and form tertiary carbocation which then in presence of water forms oxonium ion. Finally, the hydrogen present in oxonium ion (oxygen with positive charge) gets removed in presence of water that results to form the given product.

(d)

Interpretation Introduction

Interpretation:

The structure for alkene required to produce the given alcohol via acid-catalyzed hydration has to be identified.

Concept Introduction:

Acid-catalyzed hydration: It is addition of water to unsaturated bonds. In presence of strong acid such as ${\text{H}}_{\text{2}}{\text{SO}}_{\text{4}}$, alkene reacts with water to form the corresponding alcohol.

Leaving group: it is the fragment that leaves the substrate in a chemical reaction with a pair of electrons.

Nucleophile: donates pair of electrons to positively charged substrate resulting in the formation of chemical bond.

Carbocation: carbon ion that bears a positive charge on it.

Carbocation stability order:

Resonance stabilization: Due to the delocalization of electrons within the molecule the overall energy becomes lower and makes that molecule more stable.

Explanation of Solution

1. 1. The given product is $3-$ propanol. It shows that the initial required alkene should contain 3 carbon atoms and 1 $\text{C=C}$ bond with it.
2. 2. First is ${\text{H}}^{\text{+}}$ from ${\text{H}}_{\text{3}}{O}^{+}$ attacks carbon with 2 hydrogens present in $\text{C=C}$ and forms secondary carbocation.
3. 3. Then, lone pair of electrons from oxygen present in water attack the carbocation.
4. 4. Finally, the hydrogen present in oxonium ion (oxygen with positive charge) gets removed in presence of water that results to form the given product.