AskDefine | Define heterocycle

Dictionary Definition

heterocycle

Noun

1 a compound containing a heterocyclic ring [syn: heterocyclic compound, heterocyclic]
2 a ring of atoms of more than one kind; especially a ring of carbon atoms containing at least one atom that is not carbon [syn: heterocyclic ring]

User Contributed Dictionary

English

Translations

organic chemistry: a heterocyclic compound or ring
  • Italian: eterociclo

Extensive Definition

Heterocyclic compounds are organic compounds that contain a ring structure containing atoms in addition to carbon, such as sulfur, oxygen or nitrogen, as part of the ring. They may be either simple aromatic rings or non-aromatic rings. Some examples are pyridine (C5H5N), pyrimidine (C4H4N2) and dioxane (C4H8O2).
Note that compounds such as cyclopropane, an anaesthetic with explosive properties, and cyclohexane, a solvent, are not heterocyclic; they are merely cycloalkanes. The prefix 'cyclic' implies a ring structure, whereas 'hetero' refers to an atom other than carbon, as above. Many heterocyclic compounds, including some amines, are carcinogenic.
Heterocyclic chemistry is the chemistry branch dealing exclusively with synthesis, properties, and applications of heterocycles.

3-Membered rings

Heterocycles with three atoms in the ring are more reactive because of ring strain. Those containing one heteroatom are, in general, stable. Those with two heteroatoms are more likely to occur as reactive intermediates. Common 3-membered heterocycles are:

4-Membered rings

5-Membered rings

With heterocycles containing five atoms, the unsaturated compounds are frequently more stable because of aromaticity.
A large group of 5-membered ring compounds with two heteroatoms are collectively called the azoles. Dithiolanes have two sulfur atoms.

6-Membered rings

Six membered rings with a single heteroatom:
With two heteroatoms:

Heterocyclic amines and cancer

Some heterocyclic amines (HCAs) found in cooked meat are known carcinogens. Research has shown that cooking certain meats at high temperatures creates chemicals that are not present in uncooked meats. For example, heterocyclic amines are the carcinogenic chemicals formed from the cooking of muscle meats such as beef, pork, fowl, and fish. HCAs form when amino acids and creatine (a chemical found in muscles) react at high cooking temperatures. Researchers have identified 17 different HCAs resulting from the cooking of muscle meats that may pose human cancer risk. NCI's Division of Cancer Epidemiology and Genetics found a link between individuals with stomach cancer and the consumption of cooked meat, and other studies for colorectal, pancreatic, and breast cancer is associated with high intakes of well-done, fried, or barbecued meats. Other sources of protein (milk, eggs, tofu, and organ meats such as liver) have very little or no HCA content naturally or when cooked.

References

heterocycle in Arabic: حلقة غير متجانسة
heterocycle in Catalan: Compost heterocíclic
heterocycle in Czech: Heterocyklické sloučeniny
heterocycle in German: Heterocyclen
heterocycle in Spanish: Compuesto heterocíclico
heterocycle in French: Hétérocycle
heterocycle in Italian: Composto eterociclico
heterocycle in Hebrew: תרכובת הטרוציקלית
heterocycle in Macedonian: Хетероциклично соединение
heterocycle in Dutch: Heterocyclische verbinding
heterocycle in Japanese: 複素環式化合物
heterocycle in Polish: Związki heterocykliczne
heterocycle in Portuguese: Composto heterocíclico
heterocycle in Russian: Гетероциклические соединения
heterocycle in Slovak: Heterocyklická zlúčenina
heterocycle in Finnish: Heterosyklinen yhdiste
heterocycle in Swedish: Heterocykliska föreningar
heterocycle in Ukrainian: Гетероциклічні сполуки
heterocycle in Chinese: 杂环化合物
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