Pyrrole(Synthesis+Reaction)lec6
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Questions and Answers

Why does pyrrole tend to react by electrophilic substitution?

  • Due to protonation at C-2 (correct)
  • Due to reduction and oxidation reactions
  • Due to protonation at C-3
  • Due to the resulting protonated molecule adding to a protonated pyrrole

    • What is the reason for electrophilic substitution normally occurring at carbon atoms instead of nitrogen in pyrrole?

  • Preferential stability of nitrogen atoms
  • Lack of resonance structures with nitrogen atoms
  • Presence of a positive charge on nitrogen atoms
  • Presence of a negative charge on carbon atoms due to delocalization (correct)

    • Why does electrophilic substitution preferentially occur at C-2 in pyrrole?

  • Preferential stability of C-3 attack products
  • More stable intermediate from C-2 attack with three resonance structures (correct)
  • More stable intermediate from C-3 attack with three resonance structures
  • Lack of resonance structures for C-2 attack products

    • What is the result of pyrrole undergoing electrophilic substitution reaction at the 2nd position (C2)?

    <p>More stable intermediate</p> Signup and view all the answers

    Why is C-2 attack in pyrrole considered more stable than C-3 attack?

    <p>Stabilized by three resonance structures</p> Signup and view all the answers

    What type of reactions does pyrrole undergo with respect to reduction and oxidation?

    <p>Reduction and oxidation reactions</p> Signup and view all the answers

    Why are the C-atoms of a pyrrole ring more electron-rich compared to benzene?

    <p>Resonance pushes electrons from the N-atom into the ring.</p> Signup and view all the answers

    What evidence supports the aromatic character of pyrrole?

    <p>All ring bonds in pyrrole are double bonds.</p> Signup and view all the answers

    What differentiates the acidic properties of pyrrole from other secondary amines?

    <p>Participation of the N lone pair in aromatic sextet.</p> Signup and view all the answers

    Why is pyrrole sensitive to strong acids?

    <p>Protonation occurs at carbons, not at N.</p> Signup and view all the answers

    How does pyrrole react with strong bases such as KOH?

    <p>To give salt-like compounds that can be used for alkylation or acylation.</p> Signup and view all the answers

    What explains the exceptional lack of basicity in pyrrole compared to pyrrolidine?

    <p>Participation of N lone pair in pyrrole's aromatic sextet.</p> Signup and view all the answers

    What is the commercial method for synthesizing Pyrrole from Furan?

    <p>Passing Furan over ammonia in the presence of Aluminium oxide catalyst at high temperature</p> Signup and view all the answers

    How does the reactivity of Pyrrole compare to benzene in electrophilic substitution reactions?

    <p>Pyrrole is more reactive than benzene</p> Signup and view all the answers

    Which type of reactions does Pyrrole undergo that benzene does not?

    <p>Diazotization and Reimer-Tiemann reactions</p> Signup and view all the answers

    What effect does the presence of a strong acid have on Pyrrole?

    <p>Strong acids affect Pyrrole significantly</p> Signup and view all the answers

    Why is Pyrrole considered aromatic?

    <p>Due to its cyclic structure with delocalized electrons</p> Signup and view all the answers

    What is a unique feature of Pyrrole's reactivity compared to benzene?

    <p>Higher reactivity leading to easier substitutions</p> Signup and view all the answers

    What is the major amino acid found in cartilage and important for maintaining youthful skin?

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

    Which compound is used for smoking cessation to relieve withdrawal symptoms?

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

    What is the role of Glycopyrrolate in medical use?

    <p>Used in Peptic ulcer</p> Signup and view all the answers

    What property of Furan allows it to have a planar ring structure?

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

    How many non-bonding electrons are present in the furan molecule?

    <p>6</p> Signup and view all the answers

    What is the hybridization of the carbon atoms in Furan that contributes to its planar structure?

    <p>sp2</p> Signup and view all the answers

    Why does pyrrole have exceptionally strong acidic properties for a secondary amine?

    <p>As a result of the participation of N lone pair in aromaticity.</p> Signup and view all the answers

    What characteristic of pyrrole makes it resemble the reactivity of benzene derivatives like phenols and amines?

    <p>Participation of N lone pair in aromatic sextet.</p> Signup and view all the answers

    What ring bond characteristic in pyrrole contributes to its aromatic character?

    <p>Intermediate nature between single and double bonds.</p> Signup and view all the answers

    How does resonance affect the electron distribution in pyrrole compared to benzene?

    <p>It pushes electrons towards the N-atom into the ring.</p> Signup and view all the answers

    Why is pyrrole more reactive than benzene?

    <p>As a result of resonance pushing electrons into the ring.</p> Signup and view all the answers

    What impact does strong acid have on pyrrole's protonation?

    <p>Protonation takes place primarily at the C-atoms.</p> Signup and view all the answers

    Which reaction is used to synthesize pyrrole from furan commercially?

    <p>Passing furan over ammonia in the presence of an aluminum oxide catalyst at 480-490°C</p> Signup and view all the answers

    Which of the following reactions does pyrrole undergo, while benzene does not?

    <p>All of the above</p> Signup and view all the answers

    What is the major factor contributing to the increased reactivity of pyrrole compared to benzene in electrophilic substitution reactions?

    <p>The electron-rich nature of the carbon atoms in pyrrole</p> Signup and view all the answers

    Which of the following statements best explains the acidic properties of pyrrole?

    <p>The delocalization of electrons in pyrrole stabilizes the conjugate base formed upon deprotonation</p> Signup and view all the answers

    What is the effect of strong acids on pyrrole?

    <p>Pyrrole is protonated, disrupting its aromaticity</p> Signup and view all the answers

    Which of the following reactions does pyrrole undergo with respect to reduction and oxidation?

    <p>Both a and c</p> Signup and view all the answers

    Which of the following statements best explains why electrophilic substitution in pyrrole preferentially occurs at the C-2 position?

    <p>The C-2 position is stabilized by three resonance structures, while the C-3 position is stabilized by only two.</p> Signup and view all the answers

    Which of the following reactions is most likely to occur when pyrrole is treated with a strong electrophile?

    <p>Electrophilic substitution at the C-2 position</p> Signup and view all the answers

    In the electrophilic substitution reaction of pyrrole, what is the initial step that occurs?

    <p>Protonation of the C-2 position</p> Signup and view all the answers

    Which of the following statements best explains why pyrrole is more reactive towards electrophilic substitution compared to benzene?

    <p>Pyrrole has a higher electron density due to the presence of the nitrogen atom.</p> Signup and view all the answers

    What is the major product formed when pyrrole undergoes electrophilic substitution followed by further reaction with another pyrrole molecule?

    <p>Pyrrole trimer</p> Signup and view all the answers

    Which of the following statements best explains why electrophilic substitution in pyrrole typically occurs at carbon atoms rather than at the nitrogen atom?

    <p>Substitution at the nitrogen atom would disrupt the aromaticity of the ring.</p> Signup and view all the answers

    Which of the following statements about the reactivity of monosubstituted pyrroles is correct?

    <p>Monosubstituted pyrroles with electron-withdrawing groups undergo electrophilic substitution more readily than unsubstituted pyrrole.</p> Signup and view all the answers

    Which of the following statements best explains the exceptional lack of basicity in pyrrole compared to pyrrolidine?

    <p>The lone pair of electrons on the nitrogen atom in pyrrole is delocalized into the aromatic ring system, reducing its availability for protonation.</p> Signup and view all the answers

    Which of the following statements best explains why electrophilic substitution in pyrrole preferentially occurs at the 2-position (C-2)?

    <p>The 2-position is more electron-rich due to the resonance stabilization of the intermediate cation formed during electrophilic substitution.</p> Signup and view all the answers

    Which of the following statements best explains the aromaticity of furan?

    <p>Furan follows Hückel's rule for aromaticity, with 6 delocalized π electrons in the ring system.</p> Signup and view all the answers

    Which of the following statements best explains the reactivity of pyrrole towards strong acids?

    <p>Strong acids cause delocalization of the lone pair of electrons on the nitrogen atom, disrupting the aromaticity of pyrrole.</p> Signup and view all the answers

    Which of the following statements best describes the role of the nitrogen atom in the reactivity of pyrrole towards electrophilic substitution?

    <p>The nitrogen atom modulates the reactivity of pyrrole towards electrophilic substitution by participating in resonance stabilization of the intermediate cation formed during the reaction.</p> Signup and view all the answers

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