Polycyclic aromatics saturation

By proper choice of reaction conditions (metal, solvent, the order of addition of reagent and reactant), fused polycyclic aromatics can be converted to different partially reduced derivatives with high selectivity. When the red complex of naphthalene, for example, formed in the Na-NH3 solution, is quenched with aqueous ammonium chloride solution, 1,4-dihydronaphthalene is formed209 [Eq. (11.58)]. Reaction in the presence of an alcohol yields 1,4,5,8-tetrahydronaphthalene210 [Eq. (11.59)]. The Benkeser reduction affords further saturation to the isomeric octalins211 [Eq. (11.60)] or even to decalin212 [Eq. (11.61)] ... 

Recently, Bonin and Simpson (2007) showed in their study that polycyclic aromatic hydrocarbons sorptive behavior could not be solely attributed to a specific SOM chemical characteristic (i.e., aliphaticity or aromaticity) and concluded that both structure and OM physical conformation are important in sorption processes. Martin-Neto et al. (1994b) used analysis of microwave power saturation curves (Weil et al., 1994) to obtain information about HA conformation. They observed that at pH > 3.5 a typical curve of homogeneous saturation was obtained for the oxisol HA, whereas at pH 2.3 inhomogeneous saturation occurred. The peat HA showed only homogeneous saturation. However, a similar inhomogeneous trend ... 

Polycyclic aromatic nitrogen compounds, such as quinoline, indole, acridine, and carbazole, are the main nitrogen-containing compounds in oil fractions, and monocyclic pyridine and pyrrole as well as anilines are present in coal tar (Scheme 11). Saturated cyclic amines are found as products of ring hydrogenation of the compounds shown in Scheme 11 after HDN. Aliphatic amines are rarely found in fuels and only in low concentrations after HDN since their nitrogen atoms are easily removed. 

Mazeas L., Budzinski H., and Raymond N. (2002) Absence of stable carbon isotope fractionation of saturated and polycyclic aromatic hydrocarbons during aerobic bacterial degradation. Org. Geochem. 33, 1259-1272. 

The initial rate of hydrogenation of fused polycyclic aromatics increases with the number of rings present phenanthrene > naphthalene > benzene. Only one ring is generally saturated at a time. This partial hydrogenation is accomplished because... 

Despite the fact that this semi-empirical technique deals only with the sigma electron contribution and was developed for the study of saturated organic molecules, the descriptors developed by the routine have found utility in the study of polycyclic aromatic hydrocarbons, as will be shown. 

The oxidative stability of the fractions and some blends (no antioxidants or accelerators present) were measured from induction times at 170°C and 190°C using DSC.5 These times, in Table 5.14, show that for the saturates alone, oxidative stability at 170°C decreases with increasing complexity (more naphthenes, fewer isoparaffins) that is, polycyclic naphthenes do not have good oxidation resistance, as we have seen already. Polynuclear aromatic fractions added to the saturates at 16% stabilize the blends (induction times increase), with the more polynuclear and more thiophenic fractions having the greatest effect. Monoaromatics had no effect or actually decreased the stability of the more isoparaffinic fractions. We have seen this effect before, where naphthalenes and higher polycyclic aromatics due to sulfur... 

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