Furan | Lec.7
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Questions and Answers

What is the product formed from the bromination of furan in the presence of alcohol?

  • Mercuration product
  • Oxidation product
  • Pyrrole
  • 2,5-dialkoxy-2, 5-dihydrofurans (correct)

    • Why can furan behave as a diene in Diels-Alder reactions?

  • Due to the addition of sulfur compounds
  • Due to the high electronegativity of the oxygen atom (correct)
  • Due to the presence of double bonds in the ring
  • Due to the presence of nitrogen atoms

    • What is the catalyst used in the industrial synthesis of pyrrole from furans?

  • Alumina (correct)
  • Raney Ni
  • Nickel
  • Sulfuric acid

    • What type of reaction involves replacement of hydrogen or carbon dioxide from an acid in the mercuration of furan?

    <p>Substitution reaction</p> Signup and view all the answers

    What does the formylation of furan involve?

    <p>Gattermann Koch formylation</p> Signup and view all the answers

    What is Raney Ni composed mostly of?

    <p>Nickel</p> Signup and view all the answers

    What is the strongest base required for the synthesis of furan from carbohydrates?

    <p>NaOH</p> Signup and view all the answers

    In the synthesis of furan from carbohydrates, what is the first step?

    <p>Distillation of CH with sulfuric acid</p> Signup and view all the answers

    Which statement about the properties of furan is correct?

    <p>Furan has a boiling point of 31.4°C and is highly volatile at room temperature</p> Signup and view all the answers

    In electrophilic substitution reactions of furan, which position is primarily substituted?

    <p>The 2-position</p> Signup and view all the answers

    What is the reason given for furan undergoing electrophilic substitution at the 2-position?

    <p>Attack at the 2-position gives more resonance contributing structures</p> Signup and view all the answers

    What is the yield of furan reported by Wilson when furoic acid is heated to 200°C without a catalyst?

    <p>78%</p> Signup and view all the answers

    What is the key factor that contributes to the aromaticity of furan?

    <p>The presence of a planar ring structure with parallel p orbitals allowing for delocalization of electrons</p> Signup and view all the answers

    Which of the following is NOT a method for the industrial synthesis of furan?

    <p>Acid-catalyzed dehydration of sucrose</p> Signup and view all the answers

    In the Paal-Knorr synthesis of furan, what type of reaction occurs?

    <p>Cyclizing dehydration</p> Signup and view all the answers

    What is the role of the base in the Feist-Benary synthesis of furan?

    <p>To remove a proton from the α-haloketone, generating an enolate</p> Signup and view all the answers

    Which of the following statements about furan is correct?

    <p>Furan can act as a diene in Diels-Alder reactions due to the delocalization of electrons in the ring</p> Signup and view all the answers

    What is the primary medicinal use of furan derivatives?

    <p>Anticancer drugs</p> Signup and view all the answers

    Which of the following statements about the aromaticity of furan is correct?

    <p>Furan is aromatic because it has 6 delocalized pi electrons following Hückel's rule.</p> Signup and view all the answers

    In the Paal-Knorr synthesis of furan, what type of reaction occurs?

    <p>Acid-catalyzed cyclizing dehydration reaction</p> Signup and view all the answers

    Which of the following is the correct mechanism for the Feist-Benary synthesis of furan?

    <p>A base-catalyzed condensation reaction between an α-haloketone and a β-ketoester.</p> Signup and view all the answers

    Which of the following reactions is NOT a method for the industrial synthesis of furan?

    <p>Acid-catalyzed dehydration of carbohydrates</p> Signup and view all the answers

    In electrophilic substitution reactions of furan, which position is primarily substituted?

    <p>The 2-position</p> Signup and view all the answers

    Which of the following statements about the properties of furan is correct?

    <p>Furan is a diene and can participate in Diels-Alder reactions.</p> Signup and view all the answers

    What is the primary reason for the preference of electrophilic substitution at the 2-position over the 3-position in furan?

    <p>Substitution at the 2-position leads to a more stable resonance-stabilized intermediate.</p> Signup and view all the answers

    What is the primary reason for furan's solubility in most organic solvents but insolubility in ether?

    <p>The aromatic nature of furan disrupts its ability to form dipole-dipole interactions with ether.</p> Signup and view all the answers

    In the synthesis of furan from carbohydrates, what is the role of the sulfuric acid in the first step?

    <p>It acts as a dehydrating agent to remove water from the carbohydrate.</p> Signup and view all the answers

    Which of the following statements about the properties of furan is incorrect?

    <p>Furan is soluble in water and most organic solvents.</p> Signup and view all the answers

    In the reaction reported by Wilson, where a 78% yield of furan was obtained from furoic acid at 200°C without a catalyst, what was the likely mechanism?

    <p>Decarboxylation</p> Signup and view all the answers

    Which of the following statements best explains why furan undergoes electrophilic substitution reactions primarily at the 2-position?

    <p>Substitution at the 2-position leads to a more stable resonance-stabilized intermediate.</p> Signup and view all the answers

    What is the key factor that enables furan to undergo Diels-Alder cycloaddition reactions?

    <p>The high electronegativity of the oxygen atom reduces the aromaticity of furan.</p> Signup and view all the answers

    In the bromination of furan in the presence of alcohol, what is the mechanism for the formation of 2,5-dialkoxy-2,5-dihydrofurans?

    <p>The alcohol acts as a nucleophile, adding to the C-5 position of the intermediate, followed by alcoholysis of the C-2 bromide.</p> Signup and view all the answers

    Which of the following is the primary reason for using Raney Ni as a reducing agent in the reduction of furan derivatives?

    <p>Raney Ni is a fine-grained solid composed mostly of nickel, which provides a large surface area for the reduction to occur efficiently.</p> Signup and view all the answers

    In the industrial synthesis of pyrrole from furans, what is the primary role of the alumina catalyst?

    <p>To promote the cycloaddition of furan with ammonia, forming the pyrrole ring.</p> Signup and view all the answers

    Which of the following statements best describes the Gattermann-Koch formylation of furan?

    <p>It is a Vilsmeier-Haack type reaction that utilizes a formylating agent derived from an amine and a carbonyl compound.</p> Signup and view all the answers

    Which of the following reactions is NOT a common method for the synthesis of furan derivatives?

    <p>Suzuki cross-coupling reactions involving furan-based boronic acids or esters.</p> Signup and view all the answers

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