Chapter 7, Problem 64PP

(a)

Interpretation Introduction

Interpretation:

The major product for each of the given E2 reactions is has to be predicted.

Concept Introduction:

Elimination Reaction: It is just reverse reaction of addition where substituent from the given molecule is removed via $E1$ (the reaction depends only on the substrate involved in the reaction) or $E2$ (the reaction depends on both of the substituents in the reaction) mechanism.

In an elimination reaction, alkenes are formed when alkyl halides are treated with bases via eliminating one proton and one halo group of the alkyl halide.

E2 reaction is a bimolecular elimination reaction in which only one step is involved.

The product of the elimination reaction is depends upon the two β-positions of alkyl halide. If the β-positions are identical and the products formed are also identical. If the β-positions are different and the products formed are also different. This means the double bond can form in two different regions so this type of reaction is called regioselective and the products are called as regiochemical outcomes.

The bulkiness of the base controls the regioselectivity in an elimination reaction. The sterically hindered bases form less substituted alkene and non-sterically hindered bases form more substituted alkenes.

If there are two different β-protons at a β-position of alkyl halide, then on the basis of stereoselectivity the trans-isomer is favored over cis-isomer.

(b)

Interpretation Introduction

Interpretation:

The major product for each of the given E2 reactions is has to be predicted.

Concept Introduction:

Elimination Reaction: It is just reverse reaction of addition where substituent from the given molecule is removed via $E1$ (the reaction depends only on the substrate involved in the reaction) or $E2$ (the reaction depends on both of the substituents in the reaction) mechanism.

In an elimination reaction, alkenes are formed when alkyl halides are treated with bases via eliminating one proton and one halo group of the alkyl halide.

E2 reaction is a bimolecular elimination reaction in which only one step is involved.

The product of the elimination reaction is depends upon the two β-positions of alkyl halide. If the β-positions are identical and the products formed are also identical. If the β-positions are different and the products formed are also different. This means the double bond can form in two different regions so this type of reaction is called regioselective and the products are called as regiochemical outcomes.

The bulkiness of the base controls the regioselectivity in an elimination reaction. The sterically hindered bases form less substituted alkene and non-sterically hindered bases form more substituted alkenes.

If there are two different β-protons at a β-position of alkyl halide, then on the basis of stereoselectivity the trans-isomer is favored over cis-isomer.