Sulfur polycyclic

Can, H., Dimoglo, A. and Kovalishyn, V.V. (2005) Application of artificial neural networks for the prediction of sulfur polycyclic aromatic compounds retention indices. /. Mol. Struct. (Theochem), 723, 183-188. 

The organic chemical structural types believed to be characteristic of coals include complex polycyclic aromatic ring systems with connecting bridges and varied oxygen-, sulfur-, and nitrogen-containing functionalities. 

Although a large number of such compounds have been prepared, many of the mixed nitrogen-sulfur macrocycles are included in other tables, most notably in Chap. 4. Some have also been recorded in Chap. 8 as monocyclic precursors to bi- or polycyclic ligands (i.e., cryptands). The reader is directed to the tables of other chapters where the desired compound, if known, may be reported. 

Major unknowns in the mechanism by which a hydrocarbon fuel bums concern the pyrosynthesis reactions that lead to the formation of polycyclic aromatic hydrocarbons (PAHs) and soot and the oxidation chemistry of atoms other than carbon and hydrogen (heteroatoms) in the fuel, particularly nitrogen, sulfur, and halogens. 

Although pyridines and quinolines were first produced during the carbonization of coal, they are now available by synthesis in quantities that far exceed those by the former. Phosphorylated ribosides of hydroxylated and aminated pyrimidines and purines make up the basic structure of ribonucleic and deoxyribonucleic acids. The polycyclic oxaarenes are plant metabolites, while thiaarenes are primarily important components of high-sulfur petroleum that must be removed. 

Because process mixtures are complex, specialized detectors may substitute for separation efficiency. One specialized detector is the array amperometric detector, which allows selective detection of electrochemically active compounds.23 Electrochemical array detectors are discussed in greater detail in Chapter 5. Many pharmaceutical compounds are chiral, so a detector capable of determining optical purity would be extremely useful in monitoring synthetic reactions. A double-beam circular dichroism detector using a laser as the source was used for the selective detection of chiral cobalt compounds.24 The double-beam, single-source construction reduces the limitations of flicker noise. Chemiluminescence of an ozonized mixture was used as the principle for a sulfur-selective detector used to analyze pesticides, proteins, and blood thiols from rat plasma.25 Chemiluminescence using bis (2,4, 6-trichlorophenyl) oxalate was used for the selective detection of catalytically reduced nitrated polycyclic aromatic hydrocarbons from diesel exhaust.26... 

Oils C (Boscan), D (Cerro Negro), E (Athabasca) - from the class of asphaltenic-aromatic crude oils, have a high sulfur content. The first two oils coming from carbonate source rocks contain polar compounds consisting of very stable polycyclic aromatics. On the other hand, the last oil contains aromatics which are less condensed and more reactive. 

Another current development in the use of F-T chemistry in a three-phase slurry reactor is Exxon s Advanced Gas Conversion or AGC-21 technology (Eidt et al., 1994 Everett et al., 1995). The slurry reactor is the second stage of a three-step process to convert natural gas into a highly paraffinic water-clear hydrocarbon liquid. The AGC-21 technology, as in the Sasol process, is being developed to utilize the large reserves of natural gas that are too remote for economical transportation via pipelines. The converted liquid from the three-step process, which is free of sulfur, nitrogen, nickel, vanadium, asphaltenes, polycyclic aromatics, and salt, can be shipped in conventional oil tankers and utilized by most refineries or petrochemical facilities. 

Sometimes, hydrogen sulfide converts an oxygen-containing heterocycle into a sulfur-containing one, and as furans and polycyclic furans are very common in nature such reactions may be the origin of the polycyclic thiophenes mentioned above. A typical example is the formation of the isothiazolin-3-thione (6) from the isoxazolin-3-thione (7) on treatment with hydrogen sulfide and hydrogen bromide.8... 

Gimeno R.A. et al., 2002. Determination of polycyclic aromatic hydrocarbons and polycyclic aromatic sulfur heterocycles by high-performance liquid chromatography with fluorescence and atmospheric pressure chemical ionization mass spectrometry detection in seawater and sediment samples. J Chromatogr A 958 141. 

One of the most ubiquitous multiple-component contaminants that reaches the soil and deeper subsurface layers is crude oil and its refined products. In the subsurface, these contaminants are transformed differently by various mechanisms (Cozzarelli and Baber 2003). Crude oil contains a multitude of chemical components, each with different physical and chemical properties. As discussed in Chapter 4, the main groups of compounds in crude oils are saturated hydrocarbons (such as normal and branched alkanes and cycloalkanes without double bonds), aromatic hydrocarbons, resins, and asphaltenes, which are high-molecular-weight polycyclic compounds containing nitrogen, sulfur, and oxygen. 

The sediment samples were allowed to thaw at room temperature and then sieve-washed through a 2 mm stainless steel screen to remove pebbles and extraneous debris. Excess water was decanted and the wet sediment was Soxhlet extracted for several hours with Nanograde isopropyl alcohol. A further extraction with Nanograde benzene was necessary in order to isolate the polycyclic aromatic hydrocarbons. The isopropanol extract was evaporated to dryness on a rotary evaporator at 30-40°C the benzene extract was freed of elemental sulfur by passage through a column of colloidal copper [6]. 

The various, complex, cascade reactions described above converted simple saturated and aromatic heterocycles into polycyclic pentathiepins and their chlorinated and rearranged derivatives this strikingly illustrates the extensive reactivity of S2CI2 and its complexes with bases, particularly DABCO. This reactivity encompassed dehydrogenation of tetrahydroaromatics, chlorination and sulfuration of aromatics and their conversion into SSCl derivatives. 

One of the important challenges in modern synthetic and pharmaceutical chemistry is to design and develop efficient, clean, and fast routes to obtain architectural molecules from simple starting materials [102, 103]. The ewdo-selective cydoisome-rization (Scheme 4.13a) of terminal alkynes tethered to alcohols, nitrogen, and sulfur nudeophiles is one of the interesting transformations widely utilized in effident syntheses of antiviral nucleosides [104, 105], polycyclic ethers [106], and oligosac-... 

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