A heterocyclic compound or ring structure is a cyclic compound that has atoms of at least two different elements as members of its ring(s). Heterocyclic organic chemistry is the branch of organic chemistry dealing with the synthesis, properties, and applications of organic heterocycles.
Pyrimidine is an aromatic, heterocyclic, organic compound similar to pyridine. One of the three diazines, it has nitrogen atoms at positions 1 and 3 in the ring. The other diazines are pyrazine and pyridazine.
Pyridine is a basic heterocyclic organic compound with the chemical formula C5H5N. It is structurally related to benzene, with one methine group (=CH−) replaced by a nitrogen atom. It is a highly flammable, weakly alkaline, water-miscible liquid with a distinctive, unpleasant fish-like smell. Pyridine is colorless, but older or impure samples can appear yellow, due to the formation of extended, unsaturated polymeric chains, which show significant electrical conductivity. The pyridine ring occurs in many important compounds, including agrochemicals, pharmaceuticals, and vitamins. Historically, pyridine was produced from coal tar. As of 2016, it is synthesized on the scale of about 20,000 tons per year worldwide.
Pyrrole is a heterocyclic, aromatic, organic compound, a five-membered ring with the formula C4H4NH. It is a colorless volatile liquid that darkens readily upon exposure to air. Substituted derivatives are also called pyrroles, e.g., N-methylpyrrole, C4H4NCH3. Porphobilinogen, a trisubstituted pyrrole, is the biosynthetic precursor to many natural products such as heme.
Hydrazones are a class of organic compounds with the structure R1R2C=N−NH2. They are related to ketones and aldehydes by the replacement of the oxygen =O with the =N−NH2 functional group. They are formed usually by the action of hydrazine on ketones or aldehydes.
In organic chemistry, a dicarbonyl is a molecule containing two carbonyl groups. Although this term could refer to any organic compound containing two carbonyl groups, it is used more specifically to describe molecules in which both carbonyls are in close enough proximity that their reactivity is changed, such as 1,2-, 1,3-, and 1,4-dicarbonyls. Their properties often differ from those of monocarbonyls, and so they are usually considered functional groups of their own. These compounds can have symmetrical or unsymmetrical substituents on each carbonyl, and may also be functionally symmetrical or unsymmetrical.
Furan is a heterocyclic organic compound, consisting of a five-membered aromatic ring with four carbon atoms and one oxygen atom. Chemical compounds containing such rings are also referred to as furans.
Hermann Emil Louis Fischer was a German chemist and 1902 recipient of the Nobel Prize in Chemistry. He discovered the Fischer esterification. He also developed the Fischer projection, a symbolic way of drawing asymmetric carbon atoms. He also hypothesized lock and key mechanism of enzyme action. He never used his first given name, and was known throughout his life simply as Emil Fischer.
Pyrazine is a heterocyclic aromatic organic compound with the chemical formula C4H4N2. It is a symmetrical molecule with point group D2h. Pyrazine is less basic than pyridine, pyridazine and pyrimidine. It is a "deliquescent crystal or wax-like solid with a pungent, sweet, corn-like, nutty odour".
Benzofuran is the heterocyclic compound consisting of fused benzene and furan rings. This colourless liquid is a component of coal tar. Benzofuran is the "parent" of many related compounds with more complex structures. For example, psoralen is a benzofuran derivative that occurs in several plants.
Indazole, also called isoindazole, is a heterocyclic aromatic organic compound. This bicyclic compound consists of the fusion of benzene and pyrazole.
Acetylacetone is an organic compound with the chemical formula CH3−C(=O)−CH2−C(=O)−CH3. It is classified as a 1,3-diketone. It exists in equilibrium with a tautomer CH3−C(=O)−CH=C(−OH)−CH3. The mixture is a colorless liquid. These tautomers interconvert so rapidly under most conditions that they are treated as a single compound in most applications. Acetylacetone is a building block for the synthesis of many coordination complexes as well as heterocyclic compounds.
Thiazole, or 1,3-thiazole, is a 5-membered heterocyclic compound that contains both sulfur and nitrogen. The term 'thiazole' also refers to a large family of derivatives. Thiazole itself is a pale yellow liquid with a pyridine-like odor and the molecular formula C3H3NS. The thiazole ring is notable as a component of the vitamin thiamine (B1).
Pyrazole is an organic compound of azole group with the formula C3H3N2H. It is a heterocycle characterized by a 5-membered ring of three carbon atoms and two adjacent nitrogen atoms, which are in ortho-substitution. Pyrazole is a weak base, with pKb 11.5 (pKa of the conjugate acid 2.49 at 25 °C). Pyrazoles are also a class of compounds that have the ring C3N2 with adjacent nitrogen atoms. Notable drugs containing a pyrazole ring are celecoxib (celebrex) and the anabolic steroid stanozolol.
Cinnoline is an aromatic heterocyclic compound with the formula C8H6N2. It is isomeric with other naphthyridines including quinoxaline, phthalazine and quinazoline.
Phthalazine, also called benzo-orthodiazine or benzopyridazine, is a heterocyclic organic compound with the molecular formula C8H6N2. It is isomeric with other naphthyridines including quinoxaline, cinnoline and quinazoline.
Carbazole is an aromatic heterocyclic organic compound. It has a tricyclic structure, consisting of two six-membered benzene rings fused on either side of a five-membered nitrogen-containing ring. The compound's structure is based on the indole structure, but in which a second benzene ring is fused onto the five-membered ring at the 2–3 position of indole.
Indole is an aromatic, heterocyclic, organic compound with the formula C8H7N. It has a bicyclic structure, consisting of a six-membered benzene ring fused to a five-membered pyrrole ring. Indole is widely distributed in the natural environment and can be produced by a variety of bacteria. As an intercellular signal molecule, indole regulates various aspects of bacterial physiology, including spore formation, plasmid stability, resistance to drugs, biofilm formation, and virulence. The amino acid tryptophan is an indole derivative and the precursor of the neurotransmitter serotonin.
A ring forming reaction or ring-closing reaction in organic chemistry is a general term for a variety of reactions that introduce one or more rings into a molecule. A heterocycle forming reaction is such a reaction that introduces a new heterocycle. Important classes of ring forming reactions include annulations and cycloadditions.
2,1,3-Benzothiadiazole is a bicyclic molecule composed of a benzene ring that is fused to a 1,2,5-thiadiazole.
