Azoles III
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Questions and Answers

What is the characteristic of 1,2-azoles?

  • Basic compounds due to the presence of oxygen
  • Contain three hetero atoms
  • Non-aromatic compounds
  • Aromatic compounds with a lone pair of electrons on nitrogen (correct)

What is the effect of the adjacent hetero atom on the basicity of 1,2-azoles?

  • Decreases the basicity (correct)
  • Neutralizes the basicity
  • Increases the basicity
  • Has no effect on the basicity

Which of the following is the most basic compound?

  • Isoxazole
  • 1,3-azoles (correct)
  • Isothiazole
  • Pyrazole

What is the boiling point of Isoxazole?

<p>95°C (D)</p> Signup and view all the answers

What is the starting material used for the synthesis of Pyrazoles and Isoxazoles?

<p>1,3-Dicarbonyl Compounds and Hydrazines (D)</p> Signup and view all the answers

How are the rings of Azoles numbered?

<p>Start from the heteroatom with higher atomic no. (B)</p> Signup and view all the answers

What is the pKa value of Pyrazole?

<p>2.5 (D)</p> Signup and view all the answers

What is the effect of the nitrogen atom on the basicity of 1,2-azoles?

<p>Increases the basicity due to the electron-donating effect (C)</p> Signup and view all the answers

What is the boiling point of Pyrazole?

<p>186-188°C (C)</p> Signup and view all the answers

What is the structural composition of a pyrazole ring?

<p>Three carbon atoms and two nitrogen atoms (D)</p> Signup and view all the answers

What is the source of pyrazoles in nature?

<p>They are rare in nature (D)</p> Signup and view all the answers

What is the reaction involved in the synthesis of pyrazole from α,β-unsaturated aldehydes?

<p>Dehydrogenation (A)</p> Signup and view all the answers

What is the characteristic of pyrazole in nonpolar solvents like benzene?

<p>It forms dimers and trimers (D)</p> Signup and view all the answers

What is the type of nitrogen atom present in pyrazole?

<p>Both pyrrole type and pyridine type (B)</p> Signup and view all the answers

What is the characteristic of pyrazole as an amphoteric compound?

<p>It can react with both acids and bases (C)</p> Signup and view all the answers

What is the industrial method of pyrazole synthesis involving diazoalkans?

<p>Interaction with acetylene (A)</p> Signup and view all the answers

What is the novel pyrazole synthesis method involving 1,3-dinitroalkanes?

<p>Heterocycle formation (B)</p> Signup and view all the answers

What is the smell of pyrazole?

<p>Weak pyridine smell (C)</p> Signup and view all the answers

What is the functional group of the dicarbonyl component in pyrazole synthesis?

<p>Ester (A)</p> Signup and view all the answers

What is the classification of pyrazoles in terms of their occurrence in nature?

<p>Alkaloids (B)</p> Signup and view all the answers

What is the method of forming heterocyclic rings from 1,3-dinitroalkanes?

<p>Heterocycle formation (B)</p> Signup and view all the answers

What is the solubility of pyrazole in nonpolar solvents like benzene?

<p>Forms dimers and trimers (C)</p> Signup and view all the answers

What is the characteristic of pyrazole with regard to its acidity and basicity?

<p>Amphoteric (C)</p> Signup and view all the answers

Which of the following 1,2-azoles has the lowest boiling point?

<p>Isoxazole (B)</p> Signup and view all the answers

What is the reason for the difference in basicity between 1,2-azoles and 1,3-azoles?

<p>Due to the electron-withdrawing effect of the adjacent hetero atom (D)</p> Signup and view all the answers

What is the characteristic of the 1,2-azoles in terms of aromaticity?

<p>They are fully aromatic (B)</p> Signup and view all the answers

What is the most widely used method for the synthesis of pyrazoles and isoxazoles?

<p>From 1,3-dicarbonyl compounds and hydrazines or hydroxylamines (B)</p> Signup and view all the answers

What is the significance of the lone pair of electrons on the nitrogen atom in 1,2-azoles?

<p>It contributes to the basicity of the compound (D)</p> Signup and view all the answers

What is the characteristic of the nitrogen atom present in pyrazole?

<p>Both pyrrole type and pyridine type (A)</p> Signup and view all the answers

What is the effect of intermolecular hydrogen bonds in nonpolar solvents like benzene?

<p>Forms dimers and trimers (B)</p> Signup and view all the answers

What is the classification of pyrazoles in terms of their pharmacological effects?

<p>Alkaloids (A)</p> Signup and view all the answers

What is the characteristic of pyrazole in terms of its solubility?

<p>Soluble in water, ethanol, and ether (C)</p> Signup and view all the answers

What is the reaction involved in the synthesis of pyrazole from 1,3-dicarbonyl compounds?

<p>Reaction with hydrazine, alkylhydrazine, or arylhydrazine (D)</p> Signup and view all the answers

Which of the following is a characteristic of 1,2-azoles?

<p>They have a lone pair of electrons on the nitrogen atom (C)</p> Signup and view all the answers

What is the effect of the adjacent hetero atom on the basicity of 1,2-azoles?

<p>It decreases the basicity of 1,2-azoles (A)</p> Signup and view all the answers

Why are 1,3-azoles more basic than 1,2-azoles?

<p>Due to the electron-withdrawing effect of the adjacent hetero atom (A)</p> Signup and view all the answers

What is the most widely used method for the synthesis of pyrazoles and isoxazoles?

<p>Synthesis from 1,3-Dicarbonyl Compounds and Hydrazines or Hydroxylamines (A)</p> Signup and view all the answers

How are the rings of Azoles numbered?

<p>Starting from the heteroatom with the higher atomic number (C)</p> Signup and view all the answers

What is the role of hydrazine in the synthesis of pyrazole?

<p>As a reactant to form the 5-membered ring (C)</p> Signup and view all the answers

What is the reason for pyrazole's solubility in water, ethanol, and ether?

<p>Due to the formation of intermolecular hydrogen bonds (B)</p> Signup and view all the answers
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