In organic chemistry, a cyclic compound is a compound in which a series of carbon atoms are connected to form a loop or ring.^[1] Benzene is a well known example. The term "polycyclic" is used when more than one ring is formed in a single molecule for instance in naphthalene, and the term macrocycle is used for a ring containing more than a dozen atoms.

Benzene, a simple cyclic compound.

Naphthalene, a simple polycyclic compound.

Porphyrin, a simple macrocyclic compound.

Contents 1 Categorization 2 Ring-closing & opening reactions 3 External links 4 References 5 See also

[edit] Categorization

Cyclic compounds can be categorized:

• Alicyclic compound
  • Cycloalkane
  • Cycloalkene
• Aromatic hydrocarbon
  • Polycyclic aromatic hydrocarbon
• Heterocyclic compound
• Macrocycle

[edit] Ring-closing & opening reactions

Related concepts in organic chemistry are so-called ring-closing reactions in which a cyclic compound is formed and ring-opening reactions in which rings are opened.

Examples of ring-closing reactions:

• Ring-closing metathesis
• Nazarov cyclization reaction
• Ruzicka large ring synthesis
• Dieckmann condensation
• Wenker synthesis

Example of ring-opening reactions:

• A general type of polymerization reaction: Ring-opening polymerization
• Ring opening metathesis polymerisation

[edit] External links

• MeSH Polycyclic+Compounds
• MeSH Macrocyclic+Compounds

[edit] References

1. ^ March, Jerry (1985), Advanced Organic Chemistry: Reactions, Mechanisms, and Structure (3rd ed.), New York: Wiley, ISBN 0-471-85472-7 

[edit] See also

• Macrocycle
• Cyclization reaction
• Effective molarity