Condensed ring compounds

Measurements that can only be expressed as kilo-gram/kilogram or kilogram/liter are unusual because they involve amounts of substances of unknown composition. Instances of this type are not really rare. Examples are particulates in air and condensed-ring compounds in tar. Chemists can be reassured that no mention of the mole is made or needed for expressing the results of such measurements. 

Retene, Pyrene.—Other condensed benzene nuclei compounds are known. Pjrrene is a four benzene nuclei compound and retene ia a condensed ring compound found in pine tar. 

That the constitution of quinoline is that of a condensed ring compound made up of a benzene ring coupled with a pyridine ring is shown by its synthesis and its relation to pyridine. 

Aromatic hydrocarbons Benzene and similar condensed ring compounds contain delocalized rings of electrons. 

PAHs found in carbonaceous chondrites show a compositional difference from the shock-synthesized PAHs in this study. The former are predominantly condensed ring compounds, whereas the latter are dominated by polyphenyl compounds. However, many PAHs reported to be present in carbonaceous chondrites could be produced by the shock reaction from benzene. Major species of PAHs in carbonaceous chondrites such as naphthalene, biphenyl, and phenanthrene were formed abundantly in this study. Furthermore, the mutual ratios of structural isomers in the Murchison meteorite [149], the Yamato-791198 meteorite [150], and the Yamato-74662 meteorite [151] resemble those of the shock products in our experiments in particular, the coincidence in the ratios of 2-MeNap/l-MeNap and fluoranthene/pyrene is striking. This implies a genetic connection between the shock products and the organic materials in carbonaceous chondrites. 

Polynuclear, aromatic, condensed-ring compounds absorb in the same general regions as benzene derivatives " and therefore the previous section should be noted carefully. (A study of pyrenes has been published. )... 

Allyl aryl ethers are used for allylation under basic conditionsfh], but they can be cleaved under neutral conditions. Formation of the five-membered ring compound 284 based on the cyclization of 283 has been applied to the syntheses of methyl jasmonate (285)[15], and sarkomycin[169]. The trisannulation reagent 286 for steroid synthesis undergoes Pd-catalyzed cyclization and aldol condensation to afford CD rings 287 of steroids with a functionalized 18-methyl group 170]. The 3-vinylcyclopentanonecarboxylate 289, formed from 288, is useful for the synthesis of 18-hydroxyestrone (290)[I7I]. 

Many chemical compounds have been described in the Hterature as fluorescent, and since the 1950s intensive research has yielded many fluorescent compounds that provide a suitable whitening effect however, only a small number of these compounds have found practical uses. Collectively these materials are aromatic or heterocycHc compounds many of them contain condensed ring systems. An important feature of these compounds is the presence of an unintermpted chain of conjugated double bonds, the number of which is dependent on substituents as well as the planarity of the fluorescent part of the molecule. Almost all of these compounds ate derivatives of stilbene [588-59-0] or 4,4 -diaminostilbene biphenyl 5-membeted heterocycles such as triazoles, oxazoles, imidazoles, etc or 6-membeted heterocycles, eg, coumarins, naphthaUmide, t-triazine, etc. 

L. C. Behr, R. Fusco, and C. H. Jarboe, iu R. H. Wiley, ed., "Pyrazoles, Pyrazolines, PyrazoUdines, Indazoles and Condensed Rings," Vol. 22 of A. Weissberger, ed.. The Chemistry of ELetero( clic Compounds Wiley-lnterscience, New York, 1967. 

Coal tar is the condensation product obtained by cooling to approximately ambient temperature, the gas evolved in the destmctive distillation of coal. It is a black viscous Hquid denser than water and composed primarily of a complex mixture of condensed ring aromatic hydrocarbons. It may contain phenoHc compounds, aromatic nitrogen bases and their alkyl derivatives, and paraffinic and olefinic hydrocarbons. Coal-tar pitch is the residue from the distillation of coal tar. It is a black soHd having a softening point of 30—180°C (86—359°F). 

The reader is referred to previous reviews for historical aspects and early work. For condensed quinazoline systems, The Chemistry of Heterocyclic Compoundsr—Six Membered Heterocyclic Nitrogen Compounds with Four Condensed Rings should be consulted. 

A spectacular application of the acyloin ester condensation was the preparation of catenaries like 11. These were prepared by a statistical synthesis which means that an acyloin reaction of the diester 10 has been carried out in the presence of an excess of a large ring compound such as 9, with the hope that some diester molecules would be threaded through a ring, and would then undergo ring closure to give the catena compound ... 

Another class of compounds is called condensed-ring or fused-ring systems. These structures contain two or more aromatic rings that share a pair of carbon atoms. Examples include naphthalene, anthracene, and phenanthrene, the latter two being isomeric structures. 

Use of benzotriazole in the preparation of diphenylmethanes and triphenylmethanes has been reviewed." Benzotriazole is condensed with an aldehyde and then allowed to react with naphthols to form a diphenyl-methane benzotriazole derivative such as 69 (Scheme 9). The benzotriazole moiety in 69 is displaced by a Grignard reagent to give triphenylmethanes.79 100 This method allows for the preparation of triarylmethanes which contain three different aromatic rings. Compounds 70-72 are prepared by this method. 

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