Chapter 11.4, Problem 11.45P

Interpretation Introduction

Interpretation:

The mechanism for the given reaction has to be drawn.

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

Markovnikov Addition

    In the vinylic bond, if the bulky group gets substituted in the carbon atom that is more substituted means, it is known as Markovnikov’s addition.

anti-Markovnikov Addition

    In the vinylic bond, if the bulky group gets substituted in the carbon atom that is less substituted means, it is known as anti-Markovnikov’s addition.

To understand the regiochemistry of hydrogen halide addition to alkenes, the main focus will be on the carbocation intermediate.  The first step will be protonation of the double bond in alkene to form a carbocation.  Second step will be carbocation rearrangement to form a more stable carbocation.  Final step is the attack of nucleophile to give the respective product.