Recent

  • Show all results for ""

🎧 New: AI-Generated Podcasts Turn your study notes into engaging audio conversations. Learn more

Organic Chemistry: Isoxazole and Isothiazole
40 Questions
0 Views

Organic Chemistry: Isoxazole and Isothiazole

Created by
@RadiantHyena

Podcast Beta

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the characteristic of an isoxazole?

  • A four-membered ring with a carbon atom
  • A five-membered ring with an oxygen atom next to the nitrogen (correct)
  • A five-membered ring with two nitrogen atoms
  • A six-membered ring with a sulfur atom

    • What is the IUPAC name of the compound with the molecular formula C3H3NO?

  • Isothiazole
  • Ibotenic acid
  • Isoxazole (correct)
  • Furoxan

    • At what temperature does isoxazole boil?

  • 100 °C
  • 85 °C
  • 95 °C (correct)
  • 90 °C

    • What is the reaction used to synthesize isoxazole?

    <p>Reaction of 1,3-dicarbonyl compounds with hydroxylamine</p> Signup and view all the answers

    What is the role of furoxan in the human body?

    <p>A nitric oxide donor</p> Signup and view all the answers

    What is the application of isoxazole in the pharmaceutical industry?

    <p>As a drug, specifically as a COX-2 inhibitor</p> Signup and view all the answers

    What is an example of a natural product that contains an isoxazole ring?

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

    What determines the formation of pyrazole or isoxazole in 1,2-azoles preparation?

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

    What is the product of the cyclization of β-keto esters with hydroxylamine?

    <p>3-hydroxy-isoxazoles</p> Signup and view all the answers

    What is the intermediate reactant formed in the 1,3-dipolar cycloaddition reaction to produce a simple isoxazole?

    <p>Nitrile oxide</p> Signup and view all the answers

    What is the molar mass of isothiazole?

    <p>85.13 g/mol</p> Signup and view all the answers

    What is the characteristic of the ring structure of isothiazole?

    <p>It consists of three carbon atoms, one nitrogen atom, and one sulfur atom</p> Signup and view all the answers

    What is the class of compounds that isothiazole is a member of?

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

    What is the characteristic of the position of the two heteroatoms in isothiazole?

    <p>They are in adjacent positions</p> Signup and view all the answers

    What is the reactant used with propiolaldehyde to prepare isothiazole?

    <p>Sodium thiosulfate</p> Signup and view all the answers

    What is the position of the main substitution in 1,2 azole?

    <p>C-4 position</p> Signup and view all the answers

    What is the result of halogenation of pyrazole?

    <p>4-Halopyrazole</p> Signup and view all the answers

    Why is the reaction of 1,2 azole different from that of furan, pyrrole, and thiophene?

    <p>Due to the presence of the =N- group in the ring</p> Signup and view all the answers

    What is the characteristic of the reactivity of isoxazole and isothiazole?

    <p>Similar to benzene</p> Signup and view all the answers

    What is the condition required for the halogenation of isoxazole or isothiazole?

    <p>Presence of an activating group</p> Signup and view all the answers

    What is the product of the cyclo-condensation of β-chloro-α,β-unsaturated aldehydes with ammonium thiocyanate?

    <p>4,5-Disubstituted isothiazoles</p> Signup and view all the answers

    What is the product of the reaction of pyrazole with acetyl nitrate?

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

    What is the position of nitration in 3-methylisoxazole?

    <p>4-position</p> Signup and view all the answers

    Which type of pyrazoles can be C-acylated directly?

    <p>N-substituted pyrazoles</p> Signup and view all the answers

    What is the product of the Vilsmeier formylation of pyrazole?

    <p>4-formylpyrazole</p> Signup and view all the answers

    What is the temperature required for the metallation of N-sulfonyl 4-bromopyrazoles?

    <p>Low temperature</p> Signup and view all the answers

    What is the position of lithiation in N-sulfonyl 4-bromopyrazoles?

    <p>5-position</p> Signup and view all the answers

    What is the reaction that occurs during the metallation of 4-Bromopyrazoles by Metal-Halogen Exchange?

    <p>Metal-halogen exchange</p> Signup and view all the answers

    What is the significance of 1,2-Azoles in natural products and pharmaceutical drugs?

    <p>They are important components</p> Signup and view all the answers

    What is the difference between the nitration of pyrazoles and isothiazoles, compared to isoxazoles?

    <p>Isoxazoles undergo nitration in very low yield</p> Signup and view all the answers

    Which of the following isoxazoles is sufficiently reactive to undergo nitration at the 4-position?

    <p>3-methylisoxazole</p> Signup and view all the answers

    What is the major difference between the nitration of pyrazoles and isothiazoles, compared to isoxazoles?

    <p>Isoxazoles undergo nitration in very low yield</p> Signup and view all the answers

    What is the product of the reaction of pyrazole with acetyl nitrate?

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

    What is the significance of the low temperature in the metallation of N-sulfonyl 4-bromopyrazoles?

    <p>It prevents metal-halogen exchange</p> Signup and view all the answers

    What is the characteristic of the reactivity of pyrazoles and isothiazoles?

    <p>They undergo straightforward nitration</p> Signup and view all the answers

    What is the product of the Vilsmeier formylation of pyrazole?

    <p>4-formylpyrazole</p> Signup and view all the answers

    Which type of pyrazoles can be directly C-acylated?

    <p>N-substituted pyrazoles</p> Signup and view all the answers

    What is the position of nitration in the reaction of pyrazole with acetyl nitrate?

    <p>4-position</p> Signup and view all the answers

    What is the role of acid in the rearrangement of nitropyrazole?

    <p>It promotes the reaction</p> Signup and view all the answers

    What is the significance of 1,2-Azoles in natural products and pharmaceutical drugs?

    <p>They are commonly found</p> Signup and view all the answers

    Study Notes

    Isoxazole and Isothiazole

    • Isoxazole is an azole with an oxygen atom next to the nitrogen.
    • Isoxazole rings are found in some natural products, such as ibotenic acid.
    • Isoxazoles also form the basis for a number of drugs, including the COX-2 inhibitor valdecoxib (Bextra).
    • Furoxan is a nitric oxide donor.

    Isoxazole Properties

    • Molecular formula: C3H3NO
    • Boiling point: 95 °C

    Synthesis of Isoxazole

    • Reaction of 1,3-dicarbonyl compounds with hydroxylamine under mild acidic conditions.
    • 1,2-azoles preparation depending on the reagent used.
    • Cyclization of β-keto esters with hydroxylamine to provide 3-hydroxy- isoxazoles.
    • 1,3-Dipolar Cycloaddition Formation of a Simple Isoxazole.

    Isothiazole

    • IUPAC name: Isothiazole
    • Other names: 1,2-thiazole
    • Properties: Molecular formula: C3H3NS, Molar mass: 85.13 g/mol, Boiling point: 114 °C
    • An isothiazole is a type of organic compound containing a five-membered aromatic ring that consists of three carbon atoms, one nitrogen atom, and one sulfur atom.

    Isothiazole Synthesis

    • Isothiazole can be prepared from thioamides in the following way:
    • By reaction propiolaldehyde with sod.thiosulfate in the presence of ammonia solution.
    • By cyclo-condesation of β-chloro-α,β-unsaturated aldehydes with ammonium thiocyanate will give 4,5- disubstituted isothiazoles.

    Reaction of 1,2 Azole

    • Like 1,3 azole, due to the presence of =N- group in the ring, the 1,2 azole are much less reactive towards ES reactions than furan, pyrrole and thiophene.
    • 1,2 azole undergo ES reactions under an appropriate reaction condition.
    • The main substitution takes place at the C-4 position.
    • Pyrazole reactivity like phenol, but isoxazole & isothiazole reactivity like benzene.

    Halogenation of Isoxazoles, Pyrazoles and Isothiazoles

    • Halogenation (iodination, bromination) of pyrazole leads to the 4-halopyrazole.
    • Poor yields are obtained when attempting to halogenate isoxazole or isothiazole, but bromination can be accomplished when an activating group is present as a substituent.

    Nitration of Isoxazoles, Pyrazoles and Isothiazoles

    • Pyrazoles and isothiazoles undergo straightforward nitration:
      1. Nitropyrazole is formed in good yield by treatment of pyrazole with the mild nitrating reagent, acetyl nitrate.
      1. Nitropyrazole can be rearranged to give 4-nitropyrazole by treatment with acid at low temperature.
    • Isoxazole nitrates in very low yield, but 3-methylisoxazole is sufficiently reactive to undergo nitration at the 4-position.

    Acylation of Pyrazole

    • Only N-substituted pyrazoles can be C-acylated directly.
    • Vilsmeier formylation produces the 4-formylpyrazole in modest yield.

    Metallation of Pyrazole

    • Direct Metallation of 4-Bromopyrazoles.
    • At low temperature, N-sulfonyl 4-bromopyrazoles can be lithiated at 5-position without undergoing metal-halogen exchange.
    • Metallation of 4-Bromopyrazoles by Metal-Halogen Exchange.

    1,2-Azoles in Natural Products and Pharmaceutical Drugs

    • Isoxazole rings are found in some natural products, such as ibotenic acid.
    • Isoxazoles also form the basis for a number of drugs, including the COX-2 inhibitor valdecoxib (Bextra).
    • The ring structure of isothiazole is incorporated into larger compounds with biological activity such as the pharmaceutical drugs ziprasidone and perospirone.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Five_membered_with_2_heteroatoms_Isoxazole_&_Isothiazole.pdf

    Description

    Test your knowledge of isoxazole and isothiazole, types of heterocyclic compounds with 2 heteroatoms. Learn about their synthesis, reactions, and applications in natural products and pharmaceutical drugs.

    More Quizzes Like This

    Chemistry of Heterocyclic Compounds Quiz
    5 questions

    Nomenclature of Heterocyclic Compounds Quiz and Flashcards

    MasterfulVigor avatar
    MasterfulVigor
    Heterocyclic Compounds Chemistry Quiz
    5 questions

    Heterocyclic Compounds Chemistry Quiz

    BrainyHamster avatar
    BrainyHamster
    Organic chemistry
    104 questions

    Organic chemistry

    UnforgettableAmaranth avatar
    UnforgettableAmaranth
    Organic Chemistry 3 Lecture 8: Fused Heterocyclic Compounds
    40 questions

    Organic Chemistry 3 Lecture 8: Fused Heterocyclic Compounds

    RadiantHyena avatar
    RadiantHyena
    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser