Skill 19.4 Identifying heterocyclic compounds

Heterocyclic compounds are organic ring structures (-cyclic) that include an atom or atoms other than carbon (hetero-) in the ring. Thus, although compounds such as benzene and cyclohexane form organic rings, they do not include atoms other than carbon, and therefore do not qualify as heterocyclic. The particular number of elements in the ring varies, with 

Oxygen, nitrogen and sulfur are most commonly found in heterocyclic compounds, but there is no fundamental limitation to these particular elements. Examples of heterocyclic compounds include pyridine and furan. 

In addition to the single-ring examples illustrated above, heterocyclic compounds can also have multiple rings. Due to the vast number of different possible arrangements and numbers of rings, the nomenclature associated with these compounds can 

Heterocyclic compounds find prominent application in pharmaceutical and agricultural products, and they are also critical in biological processes. For example, the heterocyclic compound thymine is an important component of DNA. Thymine is also identified in lUPAC nomenclature as 5-methylpyrimidine-2,4(1 H,3H)-dione. 

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