Chapter 13, Problem 37PP

(a)

Interpretation Introduction

Interpretation:

The product for the given reaction has to be identified.

Concept introduction:

Epoxides from Peroxy acids:

The commonly used Peroxy acids are meta-Chloroperoxybenzoic acid (MCPBA) and Peroxyacetic acid. This process is stereospecific.

Reaction of Grignard reagent with epoxide will form alcohols. Grignard reagent will add to the less substituted carbon. The $\text{C-Mg}$ bond in the Grignard reagent will act as the nucleophile.

(b)

Interpretation Introduction

Interpretation:

The product for the given reaction has to be identified.

Concept introduction:

Alkoxymercuration-demercuration: the process where alcohols can be prepared from alkene, results in the markovnikov’s addition of $\text{H}\text{\& OH}$ groups across the double bond of alkene.

NaBH₄ (Sodium borohydride):

Sodium borohydride is used as a reducing agent.

Aldehydes and ketons react with sodium borohydrate undergoes reduction to forms alcohols.

(c)

Interpretation Introduction

Interpretation:

The product for the given reaction has to be identified.

Concept introduction:

Epoxides from Peroxy acids:

The commonly used Peroxy acids are meta-Chloroperoxybenzoic acid (MCPBA) and Peroxyacetic acid. This process is stereospecific.

Base catalyzed ring opening of epoxide:

The nucleophile will attack at the less substituted position under basic conditions

(d)

Interpretation Introduction

Interpretation:

The product for the given reaction has to be identified.

Concept introduction:

Reaction of metal with alcohol:

Metals can react with alcohol to produce alkoxide ion. For an example, ethanol can be react with sodium to produce hydrogen gas and sodium ethoxide.

(e)

Interpretation Introduction

Interpretation:

The product for the given reaction has to be identified.

Concept introduction:

Reaction of metal with alcohol:

Metals can react with alcohol to produce alkoxide ion. For an example, ethanol can be react with sodium to produce hydrogen gas and sodium ethoxide.

Epoxides from Peroxy acids:

The commonly used Peroxy acids are meta-Chloroperoxybenzoic acid (MCPBA) and Peroxyacetic acid. This process is stereospecific.

Acid-catalyzed ring-opening of epoxide: The epoxide ring is protonated and the nucleophile attack depends on the electronic or steric effect (nature of epoxide).

Regiochemistry: when the epoxide is unsymmetrical, the nucleophile attack at the more substituted position of the protonated epoxide ring.

Stereochemistry: when the nucleophile attack takes place at chiral center, an inversion of configuration is obtained.

Base catalyzed ring opening of epoxide:

The nucleophile will attack at the less substituted position under basic conditions

(f)

Interpretation Introduction

Interpretation:

The product for the given reaction has to be identified.

Concept introduction:

Reaction of Grignard reagent with epoxide will form alcohols. Grignard reagent will add to the less substituted carbon. The $\text{C-Mg}$ bond in the Grignard reagent will act as the nucleophile.

The reactions of Epoxides with strong nucleophiles requires a strong driving force that helps in the removal of ring strain associated with the three-membered ring of an Epoxide. These ring opening reactions also occur under acidic conditions.

The mechanism of acid-catalyzed ring opening of an Epoxide occurs in two steps.

In first step, the protonation of Epoxide occurs.

In second step, the attack of nucleophile occurs in the protonated Epoxide by ${\text{S}}_{\text{N}}\text{2}$ process.