Chapter 6, Problem 99P

Interpretation Introduction

Interpretation:

Structure and configuration of the products obtained in the given reactions has to be drawn.

Concept introduction:

Stereochemistry of addition reaction in alkenes:

The dibromination or addition of bromin in alkenes by using ${\text{Br}}_{\text{2}}{\text{/CH}}_{\text{2}}{\text{Cl}}_{\text{2}}$ is a anti-addition reaction so trans-alkene yields erythro (RS or SR) isomers and anti-addition of cis-alkene yields threo (RR or SS) isomers.

In the above reaction, the hydroxyl bromo derivative product will form when reagent ${\text{Br}}_{\text{2}}{\text{/H}}_{\text{2}}\text{O}$ is used and the ether derivative of bromo substituted compound will form, when ${\text{Br}}_{\text{2}}\text{/ROH}$ is used and these reactions are,

Hydrohalogenation:

The intermediate of addtion of hydrogen halide in alkene is carbocation so the stable carbocation is formed in the reaction then the helaide ion is added in it.

Markovnikov's rule:

It says the negative part of the reactant is added in the position of highly substituted carbon in alkene.

In the above reaction, the hydroxyl derivative will formed, when ${\text{H}}_{\text{2}}{\text{SO}}_{\text{4}}$ is used instead of $\text{HX}$.

Hydrogenation:

The reduction or addition of hydrogen in alkenes by using ${\text{H}}_{\text{2}}\text{,Pd/C}$ is a syn-addition reaction so in this reaction, cis-alkene yields erythro (RS or SR) isomers and syn addition of trans-alkene yields the threo (RR or SS) isomers.

Hydroboration:

In the addition of ${\text{BH}}_{\text{3}}$ in alkene, the borane is added in least substituted carbon in alkene and this further reacts with hydrogen peroxide and water yields alcohol. This is shown in below mechanism,