Lec 1 | Heterocyclic Compounds
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Questions and Answers

What is the correct rule for numbering a ring with multiple heteroatoms?

  • Always begin with the heteroatom with the lowest atomic number.
  • Start with the heteroatom that gives the lowest number to the next priority atom. (correct)
  • Begin with the heteroatom that has the highest priority.
  • Start with the heteroatom closest to the fused bond.

    • What is the reason for pyrrole having a high boiling point compared to furan and thiophene?

  • Higher electronegativity of nitrogen.
  • Higher molecular weight.
  • Stronger covalent bonds.
  • Presence of intermolecular hydrogen bonding. (correct)

    • Why is pyrrole considered an important heterocyclic compound?

  • Presence in naturally occurring substances like alkaloids and haemoglobin. (correct)
  • Due to its bright red color.
  • Because it contains a sulfur atom.
  • Its derivation from a Greek word.

    • What does pyrrole's name 'pyrros' in Greek signify?

    <p>Oil that catches fire easily.</p> Signup and view all the answers

    What determines the numbering of a ring with one heteroatom?

    <p>The distance from the fused bond.</p> Signup and view all the answers

    Where does pyrrole naturally occur?

    <p>In bone oil and coal-tar.</p> Signup and view all the answers

    What is the color produced when pyrrole reacts with p-dimethylaminobenzaldehyde?

    <p>Intense Red</p> Signup and view all the answers

    How is pyrrole removed during the isolation process?

    <p>Fractional distillation</p> Signup and view all the answers

    Which synthesis method involves the reaction of a-haloketones with β-ketoester in the presence of ammonia?

    <p>Hantzsch pyrrole synthesis</p> Signup and view all the answers

    What is the primary source of pyrrole in the text?

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

    What is used to wash the isolated bone oil to remove acidic substances?

    <p>Sulphuric acid</p> Signup and view all the answers

    How are saturated atoms in a partially saturated ring typically designated?

    <p>By using 'dihydro', 'trihydro', 'tetrahydro' followed by numbers indicating the position</p> Signup and view all the answers

    What is the rule followed for designating the position of fusion in benzofused compounds?

    <p>Prefix: 'benzo', Letter in square brackets, Name of heterocyclic ring</p> Signup and view all the answers

    In the nomenclature of fused systems, what do the words 'dihydro', 'trihydro', 'tetrahydro' indicate?

    <p>Number of saturated atoms in the compound</p> Signup and view all the answers

    How should substituents in a heterocyclic compound be listed?

    <p>In alphabetical order following identification by position</p> Signup and view all the answers

    What is a nonsystematic name given to an organic compound?

    <p>Trivial name</p> Signup and view all the answers

    How is the highest priority atom indicated in naming heterocyclic compounds?

    <p>#1 followed by next priority atom with lowest number</p> Signup and view all the answers

    What is the primary importance of heterocyclic compounds?

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

    Which of the following is an example of a heterocyclic compound used as a drug?

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

    Which of the following is NOT a common heterocyclic ring system?

    <p>Seven-membered N-heterocyclic rings</p> Signup and view all the answers

    What type of heterocyclic rings contain oxygen as the heteroatom?

    <p>O-heterocyclic rings</p> Signup and view all the answers

    In the nomenclature of heterocyclic compounds, what is considered when naming monoheterocyclic compounds with more than one heteroatom?

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

    Which of the following heterocyclic ring systems is NOT mentioned in the text?

    <p>Seven-membered O-heterocyclic rings</p> Signup and view all the answers

    What is the primary source of pyrrole in the text?

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

    In the Ehrlich Test, what color is produced when pyrrole reacts with p-dimethylaminobenzaldehyde?

    <p>Intense Red</p> Signup and view all the answers

    How is pyrrole removed during the isolation process?

    <p>Boiling with KOH</p> Signup and view all the answers

    Which synthesis method involves the reaction of a-haloketones with β-ketoester in the presence of ammonia?

    <p>Hantzsch pyrrole synthesis</p> Signup and view all the answers

    What is used to wash the isolated bone oil to remove basic substances?

    <p>Sulphuric acid</p> Signup and view all the answers

    Which of the following is NOT mentioned as an importance of heterocyclic compounds in the text?

    <p>Used in the synthesis of polymers</p> Signup and view all the answers

    Which of the following classes of heterocyclic rings is NOT mentioned in the text?

    <p>P-heterocyclic rings</p> Signup and view all the answers

    What is the primary consideration when naming monoheterocyclic compounds with more than one heteroatom?

    <p>The type of heteroatoms</p> Signup and view all the answers

    Which of the following heterocyclic compounds is mentioned as being used as a drug?

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

    Based on the information provided, which of the following statements about the nomenclature of heterocyclic compounds is correct?

    <p>Saturated atoms in a partially saturated ring are typically designated with a number</p> Signup and view all the answers

    Which of the following heterocyclic ring systems is considered a fused ring?

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

    Which statement correctly describes the rule for indicating the position of hetero atoms in heterocyclic compounds?

    <p>The highest priority atom is #1 and numbering proceeds in a direction that gives the next priority atom the lowest number.</p> Signup and view all the answers

    How are saturated atoms in a partially saturated heterocyclic ring designated?

    <p>By the letter 'H' followed by the number of the saturated atom.</p> Signup and view all the answers

    What is the correct order for listing substituents on a heterocyclic compound?

    <p>Substituents should be listed in alphabetical order, preceded by the number of the atom they are attached to.</p> Signup and view all the answers

    What does the prefix 'benzo' indicate in the nomenclature of benzofused heterocyclic compounds?

    <p>The presence of a benzene ring fused to the heterocyclic ring.</p> Signup and view all the answers

    What rule is followed for designating the position of fusion in benzofused heterocyclic compounds?

    <p>The position of fusion is designated by a letter in square brackets indicating the atom of the heterocyclic ring to which the benzene ring is fused.</p> Signup and view all the answers

    What is a 'trivial name' in the context of heterocyclic compounds?

    <p>A nonsystematic name that does not follow IUPAC rules.</p> Signup and view all the answers

    What is the molecular formula of pyrrole?

    <p>C4H5N</p> Signup and view all the answers

    Why does pyrrole have a relatively high boiling point compared to furan and thiophene?

    <p>Due to the presence of intermolecular hydrogen bonding in pyrrole</p> Signup and view all the answers

    Which of the following is the correct rule for numbering a ring with one heteroatom?

    <p>The heteroatom is #1, and numbering continues in the direction that is closer to the fused bond</p> Signup and view all the answers

    What is the rule for numbering a ring with more than one heteroatom?

    <p>The highest priority atom is #1, and numbering continues in the direction that gives the next priority atom the lowest number</p> Signup and view all the answers

    How are the bonds of the heterocyclic ring assigned?

    <p>By alphabetical letters starting with the 1,2-bond</p> Signup and view all the answers

    What does the name 'pyrrole' originate from?

    <p>The Greek word 'pyrros' meaning fiery oil</p> Signup and view all the answers

    Study Notes

    Heterocyclic Compounds

    • Primary importance of heterocyclic compounds: they are widely used in pharmaceuticals and biotechnology.
    • Example of a heterocyclic compound used as a drug: pyrrole.

    Pyrrole

    • Name 'pyrros' in Greek signifies fire, due to its formation during the destructive distillation of bones.
    • Naturally occurs in: bone oil.
    • Removed during the isolation process: by distillation with zinc dust or by treatment with hydrogen in the presence of a catalyst.
    • Reacts with p-dimethylaminobenzaldehyde to produce: a pink to red color.

    Nomenclature

    • Highest priority atom indicated by: a number.
    • Substituents listed: alphabetically.
    • Nonsystematic name: trivial name.
    • Primary consideration when naming monoheterocyclic compounds with more than one heteroatom: the heteroatom of highest priority.

    Ring Numbering

    • Rule for numbering a ring with one heteroatom: the heteroatom is assigned the number 1.
    • Rule for numbering a ring with more than one heteroatom: the heteroatom of highest priority is assigned the number 1.
    • Bonds of the heterocyclic ring assigned: in a clockwise direction.

    Fused Ring Systems

    • Prefix 'benzo' indicates: fusion with a benzene ring.
    • Rule for designating the position of fusion: the benzene ring is assigned the prefix 'benzo' and is numbered from the point of attachment.

    Heteroatoms

    • O-containing heterocyclic rings: oxygen as the heteroatom.
    • Dihydro, trihydro, tetrahydro indicate: the number of hydrogen atoms added to the parent compound.

    Synthesis

    • Synthesis method involving the reaction of α-haloketones with β-ketoester in the presence of ammonia: Paal-Knorr synthesis.

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    Organic Chemistry | Heterocyclic Compounds PDF

    Description

    Explore the fundamentals of organic chemistry focusing on heterocyclic compounds, including an introduction, importance, common rings, and nomenclature. Dive into the study of Pyrrole and its significance in the field of chemistry.

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