Rings condensed

Fusco, R. 1967, in Wiley, R. H. (ed.), Pyrazoles, Pyrazolines, Pyraiolidines, Indaioles. and Condensed Rings, p. 3, Interscience New York... 

The bifunctionality of the bis-diene and bis-dienophile monomers is apparent from the condensation product, structure [XXI], which still contains a diene and a dienophile in the same molecule. This polymer is crystalline, indicating a high degree of stereoregularity in the condensed rings. It decomposes to a graphitic material before melting. 

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). 

Catalysts in this service can deactivate by several different mechanisms, but deactivation is ordinarily and primarily the result of deposition of carbonaceous materials onto the catalyst surface during hydrocarbon charge-stock processing at elevated temperature. This deposit of highly dehydrogenated polymers or polynuclear-condensed ring aromatics is called coke. The deposition of coke on the catalyst results in substantial deterioration in catalyst performance. The catalyst activity, or its abiUty to convert reactants, is adversely affected by this coke deposition, and the catalyst is referred to as spent. The coke deposits on spent reforming catalyst may exceed 20 wt %. 

The anthraquiaone vat dyes can be classified into several groups on the basis of their chemical stmctures (/) benzanthrone dyes, (2) indanthrones, (3) anthrimides, (4) anthrimidocarbazoles, (5) acylaminoanthraquinones, (6) anthraquinoneazoles, (7) anthraquiaone acridones, (8) anthrapyrimidines, and 9) highly condensed ring systems. Most currendy (1993) available dyes have been known for many decades, and very few new dyes have been commercialized since the 1970s. Recendy, research and development efforts have focused on improved manufacturing of traditional vat dyes. 

Substituted and unsubstituted bi- or multi-cyclic mono-, di- or multi-olefins, i.e. containing condensed rings at least one of which contains a double bond. Norbomene is homopolymerised commercially whilst, as previously mentioned, ethylidenenorbomene and dicyclopentadiene are used as the cure site monomer in EPDM rubbers. 

Residues (petroleum), coker scrubber, condensed-ring-arom-containing Residues (petroleum), hydrogenated steam-cracked naphtha, atm tower, vacuum, light... 

Comparisons of the ultra-violet absorption spectra of the four hydrocarbons have been made with those of a series of condensed ring hydrocarbons and it is tentatively concluded that they may be derivatives of either epeiopentenophenanthrene or epeZopentenofluorene. All four hydrocarbons give a colour reaction in the Vanseheidt test. ... 

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. 

Although not presented specifically as a potential synthesis of mononuclear derivatives, the ready conversion of cyanocarbon sulfides (19) into condensed ring isothiazoles (20) is of interest and may provide new approaches to simpler isothiazoles. ... 

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. 

Various reviews dealing with the 1,2.4-triazines have been published. The most recent is that published by Neunhoeffer and Wiley (78HC749) covering the literature through 1974. Owing to the increase of the number of publications on the 1,2,4-triazines, a survey of the literature on their condensed ring systems with three- to five-membered heterocycles, from 1974 through 1992, constitutes the subject of this review. 

In the case of the aromatic hydrocarbons with condensed ring systems the state of affairs is quite similar. Thus the following structures have been proposed for naphthalene ... 

Naphthalene, anthracene, and other condensed ring systems... 

It may be mentioned that in heterocyclic systems as well as in hydrocarbon condensed ring systems the contribution to the normal state of structures associated with all of the possible positions of the double bonds is dependent on the existence of a coplanar arrangement of the per-tinent atoms, with bond angles of about 120°, which requires that the rings contain five or six or possibly seven atoms. 

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