Addition Reaction MCQ Quiz in मल्याळम - Objective Question with Answer for Addition Reaction - സൗജന്യ PDF ഡൗൺലോഡ് ചെയ്യുക

The correct option is 2 that is positional isomers . 

Concept :

• When it comes to organic chemistry, isomers are molecules that have the same molecular formula.
• That is, the same number of atoms in each element—but have various spatial or structural arrangements of their atoms.
• The three different categories of structural isomers are positional, functional group, and chain isomers. 
• Although they have different functional groups, functional group isomers share the same formula.
•  

Explanation:

Hence , Compound (A) and compound (C) are positional isomers.

Concept:

• A carbocation is a molecule in which a carbon atom has a positive charge and three bonds. The C atom in a carbocation is sp² hybridized.
• The carbocation's substituents are all in the same plane and have a bond angle of 120o between them. 
• The stability of a carbocation depends on several factors like hyperconjugation, resonance, and inductive effect. 
• Out of these factors, the resonance effect is the most important factor for the stability of a carbocation.
• The observed order of stability for carbocations is as follows:

tertiary>secondary>primary>methyl.

• Hyperconjugation effect: Hyperconjugation refers to the delocalization of electrons by participating in sigma bonds.
• It is also known as sigma bond resonance.
• The more the hyperconjugation more will be the stability of carbocation.
• A tertiary carbocation ( 3o carbocation) is more stable than a secondary carbocation 

Explanation:

• The reaction pathway is shown below:

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• In the above reaction, it is shown that in the first step of the reaction, the \(\Pi\) electrons act as a nucleophile and attacks an H⁺ ion. Which results in a secondary carbocation.
• As a tertiary carbocation ( 3o carbocation) is more stable than a secondary carbocation, thus this less stable secondary carbocation undergoes carbocation rearrangement to form a more stable tertiary carbocation.
• Finally, in the last step of the reaction, the carbocation reacts with the free Cl^- ion to form the final product.

Conclusion:-

• Hence, the major product formed in the following reaction is:

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Correct answer: 2)

Concept:

• The carbocation's substituents are all in the same plane and have a bond angle of 120^o between them. 
• Hyperconjugation effect: Hyperconjugation refers to the delocalization of electrons by participating in sigma bonds.
• It is also known as sigma bond resonance.
• The more the hyperconjugation more will be the stability of carbocation.

Explanation:

• A tertiary carbocation is more stable than secondary carbocation but here secondary carbocation is stabilized by two rings so it is more stable than tertiary.
• Next step will move with 3^o carbocation.

Conclusion:

Thus, the product of the reaction is option 2. 

Concept:

The reaction sequence you are referring to is likely the hydroboration-oxidation reaction with 1,2-bis(cyclopentadienyl)boron (Cy₂BH) in the presence of CD₃CO₂D as a deuterium source. This reaction sequence involves the following steps:

1. Hydroboration: In the first step, substrate will reacts with Cy₂BH to form the corresponding vinylborane intermediate.

2. Oxidation: The vinylborane intermediate is then oxidized with hydrogen peroxide (H₂O₂) in the presence of sodium hydroxide (NaOH) to yield the corresponding alcohol.

3. Deuterium Exchange: In the presence of CD₃CO₂D, some of the hydrogen atoms in the alcohol are replaced with deuterium atoms, resulting in the formation of the deuterated alcohol product.

4. Overall, this reaction sequence is a useful method for the selective synthesis of deuterated alcohols from alkynes. The deuterated alcohols can then be used in a variety of applications in chemistry and biology, such as for studying reaction mechanisms and metabolic pathways.

Mechanism:

Step 1: Hydroboration

The hydroboration step involves the addition of the boron compound to the carbon-carbon triple bond of 3-hexyne, forming a vinylborane intermediate.

The Cy2BH will give trans product dure to steric hyndrance

Step 2: Deuterium Exchange

In the presence of CD₃CO₂D, some of the hydrogen atoms in the alcohol product undergo deuterium exchange, resulting in the formation of the deuterated alcohol product.

The reaction mechanism can be represented as follows:

CH₃CH=CHCH₂CH₂CH₂OH + CD₃CO₂D → CH₃CD=CHCH₂CH₂CH₂OD + CD₃CO₂H

In these reactions, there is no change in conformations cis substrate gives cis product and trans substrate gives trans product.

Conclusion:
The correct answer is option 1.

Concept:

Conjugate addition:

• In conjugate addition reaction, a nucleophile reacts with an α,β-unsaturated carbonyl compound in the β- position. The negative charge carried by the nucleophile is now delocalized in the alkoxide anion and the α carbon carbanion by resonance.
• An example is shown below:

Wittig reaction:

• In the Wittig reaction, an aldehyde or a ketone is reacted with a triphenyl phosphonium ylide to yield an alkene along with triphenylphosphine oxide.
• An example is shown below:

Explanation:

• The reaction pathway is shown below:

• For the above reaction, we see that the PPh₃ (triphenylphosphine) and TBSOTf (tert-butyldimethylsilylester) undergo a conjugate addition reaction with the α,β-unsaturated carbonyl compound.
• The nBuLi (alkyl lithium reagent) abstracts a H atom from the intermediate product  and forms a triphenyl phosphonium ylide.
• The ylide reacts with butanal (Wittig reaction) to give the alkene along with triphenylphosphine oxide.
• In the last step, TBAF (Tetra-n-butylammonium fluoride) reacts with the tert-butyldimethylsilyl group and deprotects the alcohol group.

Conclusion:

Hence, the major product formed in the following reaction is 
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