Chapter 12, Problem 17PP

Interpretation Introduction

Interpretation: The reagents used to accomplish the given transformations should be identified.

Concept Introduction:

Addition Reaction: It is defined as chemical reaction in which two given molecules combines and forms product. The types of addition reactions are electrophilic addition, nucleophilic addition, free radical additions and cycloadditions. Generally, compounds with carbon-hetero atom bonds favors addition reaction.

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.

Substitution Reaction: The reaction in which one group gets substituted by other group. The types of substitution reactions are electrophilic and nucleophilic substitution reactions.

Anti-Markovnikov’s Addition Rule: The unsymmetrical alkene in a chemical compound reacts with hydrogen halide in a way, where halide ions attacks and bond to the less substitution position of carbon-carbon double bond.

To identify: The reagents used to complete the given transformations.

Answer to Problem 17PP

Explanation of Solution

Identify the reagents used in formation of products 1,2 and 3 from given substrate.

Analyzing the given product (1) shows that it lacks carbon-carbon double bond with respect to its reactant. Therefore, the given substrate undergoes reduction in presence of reagents ${\text{H}}_{\text{2}}$ and $\text{Pt}$.

The given product 2 contains one extra bromine atom when comparing with 1 since product 1 undergoes halogenation reaction. Hence the suitable reagent used in this transformation is ${\text{Br}}_{\text{2}}$

In presence of tertiary butoxide the bromine group in product 2, gets eliminated and the tertiary butoxide abstracts protons from one carbon which finally results in the formation of given substrate.

Then examining product 3 shows that the carbon in carbon-carbon double bond in given substrate is protonated to give more stable carbocation and finally the nucleophile $\text{OH}$ attacks the cation results in formation. Therefore, the reagent used for this transformation is ${\text{H}}_{\text{3}}{\text{O}}^{\text{+}}$.

Identify the reagents used in formation of products 4,5 and 6 from given substrate.

Examining product 4 shows that the substrate should undergoes anti-markovnikov addition of $\text{HBr}$ and then $\text{OH}$ should be added via substitution reaction. Therefore, the suitable reagent to accomplish the reaction is ${\text{BH}}_{\text{3}}\text{.THF}$, ${\text{H}}_{\text{2}}{\text{O}}_{\text{2}}$ and sodium hydroxide.

Analyzing the product 5 clearly shows that it contains two bromine atoms extra which is substituted in the carbon-carbon double bond in given substrate which shows that suitable reagent for the transformation is ${\text{Br}}_{\text{2}}$.

The product 6 shows that it contains one bromine atom and one $\text{OH}$ group substituted in carbon-carbon double bond in the given substrate hence suitable reagent for that is ${\text{Br}}_{\text{2}}$ and ${\text{H}}_{\text{2}}\text{O}$.

Identify the reagents used in formation of products of 7 and 8 from the given substrate.

Going through the product shows that it contains two hydroxyl groups hence suitable reagent for this transformation is ${\text{OsO}}_{\text{4}}$ which is used to add di hydroxyl group to carbon-carbon double bonds.

Product 8 shows that it contains bromine atom in less substituted atom which shows that anti-markovnikov addition happens hence suitable reagent for that is $\text{HBr}$ and $\text{ROOR}$.

Conclusion

The reagents used in the given transformations are identified by using the reaction in which the given substrate undergoes