Heterocyclic sentence example
- Carbocyclic rings will next be treated, benzene and its allies in some detail; and finally the heterocyclic nuclei.
- In classifying closed chain compounds, the first step consists in dividing them into: (1) carbocyclic, in which the ring is composed solely of carbon atoms - these are also known as homocyclic or isocyclic on account of the identity of the members of the ring - and (2) heterocyclic, in which different elements go to make up the ring.
- The elements which go to form heterocyclic rings, in addition to carbon, are oxygen, sulphur, selenium and nitrogen.
- Thus ortho-phenylene diamine yields the following products: N H N ./`N; Xn NZ In some cases oxidation of condensed benzenoid-heterocyclic nuclei results in the rupture of the heterocyclic ring with the formation of a benzene dicarboxylic acid; but if the aromatic nucleus be weakened by the introduction of an amino group, then it is the benzenoid nucleus which is destroyed and a dicarboxylic acid of the heterocyclic ring system obtained.
- Heterocyclic rings may be systematically surveyed from two aspects: (I) by arranging the rings with similar hetero-atoms according to the increasing number of carbon atoms, the so-called " homologous series "; or (2) by first dividing the ring systems according to the number of members constituting the ring, and then classifying these groups according to the nature of the hetero-atoms, the so-called " isologous series."Advertisement
- Pyrocatechin readily condenses to form heterocyclic compounds; cyclic esters are formed by phosphorus trichloride and oxychloride, carbonyl chloride, sulphuryl chloride, &c.; whilst ortho-phenylenediamine, o-aminophenol, and o-aminothiophenol give phenazine, phenoxazine and thiodiphenylamine.
- Components of cooked meat that have been suggested to cause this include heterocyclic amines, polycyclic aromatic hydrocarbons, nitrogenous residues and iron.
- Alternatively, the problem might be caused by compounds called heterocyclic amines, carcinogenic compounds created in the cooking process.
- Bupropion (Wellbutrin) is a heterocyclic antidepressant.
- There also exists an extensive class of compounds termed the " heterocyclic series " - these compounds are derived from ring systems containing atoms other than carbon; this class is more generally allied to the aromatic series than to the aliphatic.Advertisement
- As a useful preliminary it is convenient to divide heterocyclic ring systems into two leading groups: (I) systems resulting from simple internal dehydration (or similar condensations) of saturated aliphatic compounds - such compounds are: the internal anhydrides or cyclic ethers of the glycols and thioglycols (ethylene oxide, &c.); the cyclic alkyleneimides resulting from the splitting off of ammonia between the amino groups of diaminoparaffins (pyrrolidine, piperazine, &c.); the cyclic esters of oxycarboxylic acids (lactones, lactides); the internal anhydrides of aminocarboxylic acids (lactams, betaines); cyclic derivatives of dicarboxylic acids (anhydrides, imides, alkylen-esters, alkylenamides, &c.).
- The skeletons of these types are (the carbon atoms are omitted for brevity): We have previously referred to the condensation of heterocyclic ring systems containing two vicinal carbon atoms with benzene, naphthalene and other nuclei.
- The more important nuclei of this type have received special and non-systematic names; when this is not the case, such terms as phen-, benzo-, naphthoare prefixed to the name of the heterocyclic ring.