Synthesis and Reactivity of O Atom MCQ Quiz - Objective Question with Answer for Synthesis and Reactivity of O Atom - Download Free PDF

Concept:-

​Feist–Benary synthesis

• The Feist–Benary synthesis is an organic reaction between α-halogen ketones and β-dicarbonyl compounds to produce substituted furan compounds. 
• This condensation reaction is catalyzed by amines such as ammonia and pyridine.
• The first step in the ring synthesis is related to the Knoevenagel condensation. In the second step, the enolate displaces an alkyl halogen in a nucleophilic aliphatic substitution.

Explanation:-

Feist-Benary Synthesis of furan derivative:

• In the first step of the reaction, the 1,3-dicarbonyl compound reacts with aq. NaOH to give the enolate as an intermediate.
• The enolate intermediate reacts with the α-halo-ketone, followed by a reaction with aq, NaOH to give the final product.

​Conclusion:-

• The major product P in the following reaction is

Concept:-

​Feist–Benary synthesis

• The Feist–Benary synthesis is an organic reaction between α-halogen ketones and β-dicarbonyl compounds to produce substituted furan compounds. 
• This condensation reaction is catalyzed by amines such as ammonia and pyridine.
• The first step in the ring synthesis is related to the Knoevenagel condensation. In the second step, the enolate displaces an alkyl halogen in a nucleophilic aliphatic substitution.

Explanation:-

Feist-Benary Synthesis of furan derivative:

• In the first step of the reaction, the 1,3-dicarbonyl compound reacts with aq. NaOH to give the enolate as an intermediate.
• The enolate intermediate reacts with the α-halo-ketone, followed by a reaction with aq, NaOH to give the final product.

​Conclusion:-

• The major product P in the following reaction is

Explanation:-

• The reaction pathway is shown below:

• In the first step of the reaction, NaH acts as a base and abstracts the most acidic proton from the \(\alpha\)-H atom.
• The resulting carbanion reacts with the ethyl 2-chloropropanoate and gives the intermediate product.
• In the next step of the reaction, the intermediate product reacts with HCl and as soon as the ester is partly reduced, it loses water to give the furan derivative whose aromaticity prevents further reduction even with LiAlH₄ to give the final product.

Conclusion:-

• Hence, the products A and B in the following reaction will be

A is , B is 

Explanation:-

Mechanism:

The reaction pathway is shown below-

• When 1-bromo-2-fluorobenzene is treated with Mg, Benzyne intermediate is formed.
• Benzyne intermediate acts as electrophilic and can act as a dienophile in diels alder reaction." id="MathJax-Element-3-Frame" role="presentation" style="display: inline-table; line-height: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;" tabindex="0">" id="MathJax-Element-1-Frame" role="presentation" style="position: relative;" tabindex="0">
• In the next step of the reaction, the benzyne intermediate reacts with furan to give a diles alder reaction.

Conclusion:-

• Hence, the reaction of 1-bromo-2-fluorobenzene with furan in the presence of one equivalent of Mg gives

Explanation:

• 1,4-Dicarbonyl Compounds with dehydrating agent undergoes cyclodehydration to form furans. The process involves the addition of the enol oxygen of one carbonyl group to the other carbonyl group & then the elimination of water.

Conclusion:-

• Hence, the major product formed in the reaction of 2,5-hexanedione with P2O5 is