Question

What epoxide is needed to convertCH₃CH₂MgBrto each of the following alcohols, after quenching with water?

a.

b.

c.

d.

Short answer

Answer

The epoxides needed to convert CH₃CH₂MgBr to each of the following alcohols, after quenching with water, are shown below:

a.

b.

c.

d.

Step-by-step solution

Step-by-Step Solution Step 1: Function of Mg

Mg is inserted into the carbon-halogen bond to form the organomagnesium reagent known as a Grignard reagent.

They are useful for many nucleophilic attacks, such as opening of the epoxide ring to form alcohols. These reactions are highly stereospecific. During the opening of the epoxide ring, the nucleophilic attack takes place in those carbon centers that are less hindered.

Function of  H3O+

Aqueous workup, i.e., the addition of water in an acidic medium, is a quenching process that is done so that the oxygen carrying the negative charge after nucleophilic reactions get protonated.

Hence, the epoxides needed to convert CH₃CH₂MgBr to each of the following alcohols after quenching with water, are shown below:

a.

Preparation of a. from epoxide

Here the Grignard reagent attacks from the opposite side of the epoxide ring.

b.

Preparation of b. from epoxide

Here the Grignard reagent attacks from the less hindered carbon center.

c.

Preparation of c. from epoxide

Here the Grignard reagent attacks from the less hindered carbon center.

d.

Preparation of d. from epoxide

Here the Grignard reagent attacks from the less hindered carbon center.