Chapter 13, Problem 13.24UKC

(a)

Interpretation Introduction

Interpretation:

The IUPAC name of the given compound and the products of the given reaction to be predicted

Concept Introduction:

IUPAC naming nomenclature:

• Name the parent compound: Find the longest chain containing the double bond or triple bond and add the suffix ‘-ene’ or ‘-yne’ to the end of the main chain name.
• Number the carbon atoms in the main chain so that those with multiple bonds have the lowest index numbers possible:
• Write the full name: List the substituents in alphabetical order. Use commas to separate the numbers and the hyphen to separate number from words.  Indicate the position of double or triple bond in chain by giving the number of the first multiple-bond carbon.

Addition reaction: A general reaction type in which a substance X-Y adds to the multiple bond of an unsaturated reactant to yield a saturated product that has only single bonds.

Hydrohalogenation (Addition of hydrogen halide to alkenes): The addition of hydrogen halide to a multiple bond to give an alkyl halide product.

Hydration: The Addition of water to a multiple bond to give an alcohol product. An alkene does not react with pure water alone; it requires a small amount of acid to catalyst the reaction.

Alkene isomerization: The location of double bond is changed in the reaction process.

• Markovnikov’s rule: In the addition of $\text{HX}$ to an alkene, the major product arises as the nucleophile attached to the less substituent carbon centre and hydrogen attached to the more substituent carbon centre.

Answer to Problem 13.24UKC

The IUPAC name of the compound is 2,5-Dimethyl-2-heptene.

The products obtained respectively are,

Explanation of Solution

In the given compound, the parent chain has seven carbons with the double bond between $\text{C-2}$ and C-3. The numbering done in the priority order, in which the substituents gets the lowest possible number. The parent name is 2-heptene. Include the substituents in the IUPAC name with the lowest possible number. The methyl group is located at both second and fifth carbon.

Therefore, the IUPAC name of the compound is 2,5-Dimethyl-2-heptene.

Hydrohalogenation reaction:

In the given above reaction, the addition of $\text{HBr}$ across the double bond gives rise to the formation of carbocation, the tertiary carbocation is highly stable than the secondary carbocation and the nucleophilic attack of bromide ion at the carbocation centre leads to the product formation. In the product, the hydrogen attached at the less substituted carbon centre and thus the reaction follows Markonivok’ rule. The product obtained is MAJOR due to the high stability of carbocation formation.

Hydration reaction:

The addition of water molecule across the double bond requires small amount of acid to catalyse the reaction. In the given above reaction, the addition of acidic proton across the double bond gives rise to the formation of carbocation, the tertiary carbocation is highly stable and the nucleophilic attack of water molecule at the carbocation centre leads to the product formation followed by deprotonation. In the product, the hydrogen attached at the less substituted carbon centre and the reaction follows Markonivok’ rule. The product obtained is MAJOR due to the high stability of carbocation formation.

Acid-catalysed reaction:

The reaction of alkene with acid (as catalyst) indicates no other reagent is present. The protonation of alkene forms the tertiary carbocation intermediate. The deprotonation that occur in the intermediate leads to the di-substituted alkene. The reaction is an alkene isomerization.

(b)

Interpretation Introduction

Interpretation:

The IUPAC name of the given compound and the products of the given reaction to be predicted

Concept Introduction:

IUPAC naming nomenclature:

• Name the parent compound: Find the longest chain containing the double bond or triple bond and add the suffix ‘-ene’ or ‘-yne’ to the end of the main chain name.
• Number the carbon atoms in the main chain so that those with multiple bonds have the lowest index numbers possible:
• Write the full name: List the substituents in alphabetical order. Use commas to separate the numbers and the hyphen to separate number from words.  Indicate the position of double or triple bond in chain by giving the number of the first multiple-bond carbon.

Addition reaction: A general reaction type in which a substance X-Y adds to the multiple bond of an unsaturated reactant to yield a saturated product that has only single bonds.

Hydrohalogenation (Addition of hydrogen halide to alkenes): The addition of hydrogen halide to a multiple bond to give an alkyl halide product.

Hydration: The Addition of water to a multiple bond to give an alcohol product. An alkene does not react with pure water alone; it requires a small amount of acid to catalyst the reaction.

Alkene isomerization: The location of double bond is changed in the reaction process.

• Markovnikov’s rule: In the addition of $\text{HX}$ to an alkene, the major product arises as the nucleophile attached to the less substituent carbon centre and hydrogen attached to the more substituent carbon centre.

Answer to Problem 13.24UKC

The IUPAC name of the compound is 2,5-Dimethyl-2-heptene.

The products obtained respectively are,

Explanation of Solution

In the given compound, the parent chain has five carbons with the double bond between C-1 and C-2. The numbering done in the priority order, in which the substituents gets the lowest possible number. The parent name is 1-cyclopentene. Include the substituents in the IUPAC name with the lowest possible number. Two methyl groups are located at third carbon.

Therefore, the IUPAC name of the compound is 3,3-Dimethyl-1-cyclopentene.

Hydrohalogenation reaction:

In the given above reaction, the addition of $\text{HBr}$ across the double bond gives rise to the formation of carbocation, the secondary carbocation; the methyl shift occurred which leads to stable tertiary carbocation and the nucleophilic attack of bromide ion at the carbocation centre leads to the product formation. In the product, the hydrogen attached at the less substituted carbon centre and thus the reaction follows Markonivok’ rule. The product obtained is MAJOR due to the high stability of carbocation formation.

Hydration reaction:

The addition of water molecule across the double bond requires small amount of acid to catalyse the reaction. In the given above reaction, the addition of acidic proton across the double bond gives rise to the formation of carbocation; the methyl shift occurred which leads to stable tertiary carbocation and the nucleophilic attack of water molecule at the carbocation centre leads to the product formation followed by deprotonation. In the product, the hydrogen attached at the less substituted carbon centre and the reaction follows Markonivok’ rule. The product obtained is MAJOR due to the high stability of carbocation formation.

Acid-catalysed reaction:

The reaction of alkene with acid (as catalyst) indicates no other reagent is present. The protonation of alkene forms the secondary carbocation intermediate; the methyl shift occurred which leads to stable tertiary carbocation. The deprotonation that occur in the intermediate leads to the tetra-substituted alkene. The reaction is an alkene isomerization.