Chapter 11.10, Problem 11.109P

Interpretation Introduction

Interpretation:

The product that will be formed in the given reaction has to be predicted.

Concept Introduction:

Addition reactions are the one in which the groups are added to an unsaturated double bond.  The double bond is destroyed because the groups are added across the double bond.  If the considered alkene is a symmetrical one, then there is no difference in the product obtained but if the alkene is an unsymmetrical one, then regiochemistry decides the products that are obtained.

When two similar groups are added across a double bond, regiochemistry is irrelevant but stereochemistry can be relevant.  When adding two different groups across the double bond of an unsymmetrical alkene, the regiochemistry becomes relevant and stereochemistry also.  In simple words, it can be said that, when two different groups are added across a double bond, then regiochemistry becomes relevant.

Stereochemistry can also be determined for the product obtained by the way of addition of groups that adds across the double bond.  If the two groups add in the same side of the plane means it is known as syn addition and if the two groups add in the opposite side of the plane means it is known as anti addition.  This can be done by considering the given alkene in a planar form by using wedge and dash bonds.

In case of addition reaction involving two hydroxyl groups, by the choice of reagent, the fashion in which the hydroxyl group gets added can be controlled.  Either syn-addition or anti-addition can be accomplished.  In order to add the two hydroxyl group in an anti fashion, peroxy acid is employed.  First step is the formation of epoxide and then the second step is the acid-catalysis with water.  The complete reaction profile for the anti addition of two hydroxyl groups can be summarized as shown below,