Chapter 7, Problem 97IP

(a)

Interpretation Introduction

Interpretation:

The reason for mechanism shown is inconsistent that diastereomer of compound one gives E-isomer has to be explained.

Concept Introduction:

Elimination reaction: In this reaction, two substituents are removed from the substrate to give the product in presence of base.  Elimination of compound in presence of bulky base leads to less substituted alkene, in presence of strong base (not bulky) leads to more substituted alkene.  A general elimination E2 mechanism is given as,

(b)

Interpretation Introduction

Interpretation:

The reaction has to be classified and explained as stereo selective or stereospecific.

Concept Introduction:

Stereoselective: A stereoselective reaction where only one stereoisomer reacts among mixture of stereoisomers reacts. This reaction gives two or more stereoisomers but produces almost only one stereoisomer product.

Stereospecific: In this reaction, one stereoisomer of reactant gives one specific stereoisomer product and different stereoisomer of same reactant give its corresponding stereoisomer of same product.  The stereochemistry of product depends on stereochemistry of reactants.