Heterocyclic Compound

Have you ever wondered how we encounter many heterocyclic compounds in our daily lives?

  • Nucleic Acid that is present in the body responsible for storing and expressing genetic information, is an example of a Heterocyclic compound.
  • Essential micronutrient vitamins are also an example of a heterocyclic compound.
  • The majority of drugs, pesticides, dyes, and plastics are examples of heterocyclic compounds.

Table of Content

What is a Heterocyclic Compound?

A heterocyclic compound has at least two different elements as a member of its ring.

  • The most common hetero atoms found on a cyclic ring are Oxygen (O), Nitrogen (N) and Sulphur (S).

Example:

  • Nucleic Acid that is present in the body responsible for storing and expressing genetic information, is an example of a Heterocyclic compound.
  • Essential micronutrient, Vitamins is also an example of a heterocyclic compound.
  • The majority of drugs, pesticides, dyes, and plastics are examples of heterocyclic compounds.

Classification of Heterocyclic Compounds

Based on the electronic arrangement, we can classify Heterocyclic compounds into two types:

  • Aliphatic Heterocyclic Compounds
  • Aromatic Heterocyclic Compounds

Aliphatic Heterocyclic Compounds

  • Aliphatic heterocyclic compounds are those cyclic heterocycles that do not contain any double bond.
  • The properties of aliphatic heterocyclic compounds are mainly affected due to ring strain.
  • Examples of aliphatic heterocyclic compounds are Aziridine, Ethylene Oxide, Thiirane, Oxetane, Azetidine, Thietane, Tetrahydrofuran (THF), Dioxane, Pyrrolidine, Piperidine, etc.

Aromatic Heterocyclic Compound

  • Aromatic heterocyclic compounds, as the name suggests, are cyclic aromatic compounds.
  • Aromatic Heterocyclic compounds obey Huckels Rule, i.e.
  • It should be cyclic.
  • It should be planar.
  • It should not contain any sp3 hybridised atoms.
  • It must have (4n+2) 𝛑 electrons.
  • Aromatic Heterocyclic compounds are analogous to Benzene.
  • Examples: Furan, Pyrrole, Thiophene, Indole, Benzofuran, Carbazole, Quinoline, Isoquinoline, Imidazole, Oxazole, Pyrazole, Pyridazine, Pyrimidine, Purine, etc.

Based on structure, we can classify Heterocyclic compounds into five types:

  1. Three-Membered Heterocyclic Compounds
  2. Four-Membered Heterocyclic Compounds
  3. Five-Membered Heterocyclic Compounds
  4. Six-Membered Heterocyclic Compounds
  5. Condensed or Fused Heterocyclic Compounds

Three-Membered Heterocyclic Compounds

These heterocyclic compounds contain three atoms which may be saturated or unsaturated.

Based on the number of heteroatoms present, we can further classify them into two categories:

Heterocyclic compounds with one heteroatom.

  • As the name suggests, it has one heteroatom present in its ring.
  • Examples: Aziridine, Oxirane, Thiirane, Azirine, Oxirene and Thiirene.

Heterocyclic compounds with more than one heteroatom.

  • As the name suggests, it has more than one heteroatom present in its ring.
  • The heteroatom atom in the ring can be the same or different.
  • Examples: Diaziridine and Oxiaziridine.

Heterocyclic Compound 01

Four-Membered Heterocyclic Compounds

These heterocyclic compounds contain four atoms which may be saturated or unsaturated.

Based on the number of heteroatoms present, we can further classify them into two categories:

Heterocyclic compounds with one heteroatom.

  • As the name suggests, it has one heteroatom present in its ring.
  • Examples: Azetidine, Oxetane, Thietane, Azete, Oxete, Thiete, etc

Heterocyclic compounds with more than one heteroatom.

  • As the name suggests, it has more than one heteroatom present in its ring.
  • The heteroatom atom in the ring can be the same or different.
  • Examples: Diazetidine and Dioxetane.

Heterocyclic Compound 02

Five-Membered Heterocyclic Compounds

These heterocyclic compounds are derived from Benzene by replacing a C=C bond with a hetero atom having a lone pair of electrons.

Based on the number of heteroatoms present, we can further classify them into two categories:

Heterocyclic compounds with one heteroatom.

  • As the name suggests, it has one heteroatom present in its ring.
  • Examples: furan, pyrrole and thiophene.

Heterocyclic compounds with more than one heteroatom.

  • As the name suggests, it has more than one heteroatom present in its ring.
  • The heteroatom atom in the ring can be the same or different.
  • Examples: Pyrazole, Imidazole, Oxazole, Thiazole, Triazole and Tetrazole, etc.

Six-Membered Heterocyclic Compounds

These heterocyclic compounds are derived from Benzene by replacing one of the Carbon with a hetero atom having a lone pair of electrons.

Based on the number of heteroatoms present, we can further classify them into two categories:

Heterocyclic compounds with one heteroatom.

  • As the name suggests, it has one heteroatom present in its ring.
  • Examples: Pyridine, Pyran, Thiopyran, etc.

Heterocyclic compounds with more than one heteroatom.

  • As the name suggests, it has more than one heteroatom present in its ring.
  • The heteroatom atom in the ring can be the same or different.
  • Examples: Pyridazine, Pyrimidine, Pyrazine, etc.

Condensed or Fused Heterocyclic Compound

  • Condensed or Fused Heterocyclic Compound contains two or more fused rings.
  • Condensed or Fused Heterocyclic Compounds can be partly carbocyclic or partly heterocyclic.
  • Examples: Indole, Quinoine, Isoquionoline, Cabazole, etc.
  • Condensed or Fused Heterocyclic Compounds can also be completely heterocyclic.
  • Examples: Purine, Pteridine, etc.

Applications of Heterocyclic Compound

  • Heterocyclic compounds are used in agrochemicals and pharmaceuticals industries.
  • Heterocyclic compounds are used as starting materials in the synthesis of organic compounds.
  • Heterocyclic compounds are used in corrosion inhibitors, sanitisers, anti-ordinates, and developers.
  • Heterocyclic compounds are used in pesticides, dyes and plastics.

Frequently Asked Questions on Heterocyclic Compound

Q1

What is a heterocyclic compound?

A heterocyclic compound has at least two different elements as a member of its ring.

  • The most common hetero atoms found on a cyclic ring are Oxygen (O), Nitrogen (N) and Sulphur (S).
Q2

What is an aliphatic heterocyclic compound?

  • Aliphatic Heterocyclic compounds are those cyclic heterocycles that do not contain any double bond.
  • The properties of aliphatic heterocyclic compounds are mainly affected due to ring strain.
  • Examples of aliphatic heterocyclic compounds are Aziridine, Oxirane, Thiirane, etc.
Q3

What is an aromatic heterocyclic compound?

  • Aromatic Heterocyclic compounds, as the name suggests, are cyclic aromatic compounds.
  • Aliphatic Heterocyclic compounds obey Huckel’s Rule, i.e.
  • It should be cyclic.
  • It should be planar.
  • It should not contain any sp3 hybridised atoms.
  • It must have (4n+2) 𝛑 electrons.
  • Aromatic Heterocyclic compounds are analogous to Benzene.
  • Examples of aromatic heterocyclic compounds are Pyridine, Furan, Pyrrole, etc.
Q4

What are the applications of the heterocyclic compound?

  • Heterocyclic compounds are used in agrochemicals and pharmaceutical industries.
  • Heterocyclic compounds are used as starting materials in the synthesis of organic compounds.
  • Heterocyclic compounds are used in corrosion inhibitors, sanitisers, anti-ordinates, and developers.
  • Heterocyclic compounds are used in pesticides, dyes and plastics.
Q5

Give examples of a five-membered heterocyclic compound.

Pyrazole, Imidazole, Oxazole, Thiazole, Triazole, Tetrazole, Furan, Pyrrole and Thiophene

 

Comments

Leave a Comment

Your Mobile number and Email id will not be published.

*

*

close
close

Play

&

Win