30 Questions
Which compound is least basic?
Which of the following is most reactive in electrophilic aromatic substitution?
Which of the following is not true about the five-membered rings?
Five membered rings are more stable than 6 membered rings
Which of the following five-membered rings is most resonance stabilized?
Pyrrole
Five-membered rings come under which category of heterocyclic classification on the basis of chemical behavior?
deficient heterocycle
What is the reactivity order in the following five-membered heterocyclic compounds?
Pyrrole > Furan > Thiophene > Pyridine
What is the correct order of basicity of the five-membered heterocyclic compounds?
pyrrole > furan > thiophene
Which of the following is not a five-membered ring?
All of the above
Which electrophilic substitution reaction does pyridine not undergo?
Friedel-Crafts reaction
What is the IUPAC name of the structure 1,2-diazete?
1,2-dihydro-1,2-diazete
What is the common name of the structure of a six-membered ring containing two nitrogen atoms?
Pyrimidine
What is the IUPAC name of 1-methyl-1H-indazole?
1-methyl-1H-benzo[b]pyrazole
What is the name of a six-membered heterocyclic containing two nitrogen atoms?
Pyridazine
Compared to pyridine, imidazole is:
More basic
What is the correct order of reactivity (most reactive first) of pyrrole, furan, and thiophene towards electrophiles?
Pyrrole > Furan > Thiophene
Which of the following heterocyclic compounds has a five-membered ring with one nitrogen atom?
Pyrrole
Which statement about thiophene is incorrect?
Thiophene is less reactive than pyrrole
Which drug possesses a pyrrole heterocyclic compound?
Miconazole
What is the correct suffix for saturated 3-membered nitrogen heterocycles?
Iridine
Electrophilic substitution in furan usually occurs at which atom?
Both the C2 and C3 atoms
Which of the following compounds has S and N atoms?
Thiazole
Cinnoline is fused with a benzene ring to form a:
Five-membered ring
Which of the following is a method of synthesizing pyridine?
Chichibabin reaction
What is the IUPAC name of the structure below?
2H-1,4,5-Oxadiazine
Which of the following derivatives of pyridine is mostly found in mammals?
Nicotinamide
What is the correct IUPAC name of the structure below?
2H-oxete
Which of the following is an example of cyclic ether?
Oxetane
What is the correct IUPAC name of the structure below?
pyrimido[2,1-c][1,4]thiazine
What is the correct IUPAC name of the structure below?
4-methylthieno[2,3-b]furan
What is the correct IUPAC name of the structure below?
1H-benzo[g]indole
Study Notes
Heterocyclic Compounds
- Heterocyclic compounds can be classified as excessive, deficient, or equivalent based on their chemical behavior.
- Five-membered rings, such as furan, thiophene, and pyrrole, come under the category of equivalent heterocycles.
- Pyridine, a six-membered ring, is an example of an excessive heterocycle.
Reactivity of Heterocycles
- Electrophilic substitution in furan usually occurs at the C2 and C3 atoms.
- Thiophene is less reactive than pyrrole towards electrophiles.
- Pyridine does not undergo electrophilic substitution.
- The reactivity order of pyrrole, furan, and thiophene towards electrophiles is pyrrole > furan > thiophene.
Basicity of Heterocycles
- Imidazole is more basic than pyridine.
- Pyridine is less basic than pyrrole.
- The basicity of five-membered rings depends on the type of heteroatom and the resonance stabilization.
Nomenclature of Heterocycles
- The IUPAC name of a heterocycle depends on the type of heteroatom, the size of the ring, and the functional groups attached.
- Examples of IUPAC names include pyrrole, furan, thiophene, pyridine, and pyrimidine.
Synthesis of Heterocycles
- The Chichibabin reaction is a method of synthesizing pyridine derivatives.
- The Hantzsch pyridine synthesis is a method of synthesizing pyridine.
- The Bonnemann cyclisation is a method of synthesizing heterocycles.
Importance of Heterocycles
- Heterocycles are found in many biomolecules, such as vitamins (e.g., Niacin) and amino acids.
- Heterocycles have a wide range of applications in medicine, agriculture, and industry.
Other Key Facts
- Aziridine is a three-membered ring with one nitrogen atom.
- Morpholine is a saturated six-membered ring with one oxygen atom and one nitrogen atom.
- Cinnoline is a fused benzene ring with a five-membered ring.
- Penicillin is an example of a drug that contains a heterocyclic compound.
Test your knowledge of organic chemistry reactions, including basicity, electrophilic aromatic substitution, and aromatic compounds.
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