Fluoranthenes, formation

Gorelick NJ, Hutchins DA, Tannenbaum SR, Wogan GN Formation of DNA and hemoglobin adducts of fluoranthene after single and multiple exposures. Carcinogenesis 10 1579-1587, 1989... 

The predicted antiaromaticity in fluoranthene-PAH carbocations (NICS) could well be the origin of the observed paratropicity and proton shielding in these nonalternant-PAH carbocations. The observed broadening in the proton spectra in several cases, the appearance of upfield-shifted broad humps, and the formation of insoluble precipitates (which upon quenching returned the intact PAH) were taken as evidence for the concomitant presence of the RC which could additionally contribute to proton shielding. 

Figure 10.35 is the GC-MS m/z 247 profile of the nitrofluoranthenes and nitropyrenes in an extract of an ambient particle sample collected at night (Arey et al., 1988b). The high ratio of 2-nitrofluoranthene to 2-nit-ropyrene observed in this nighttime sample is indicative of nighttime gas-phase NO, radical reactions (for a review, see Kwok et al., 1994b). An NO, radical initiated mechanism for atmospheric formation of 2-nitrofluoranthene is shown in Fig. 10.36 (Atkinson and Arey, 1997 Arey, 1998a, and references therein). Analogous to the OH reaction, NO, is proposed to add to the ring to form a fluoranthene-NO, adduct, followed by ortho addition of N02 and subsequent loss of HNO,. This reaction is noteworthy because of its selectivity i.e., only 2-nitrofluoranthene is formed, and in high yield (24%) compared to the OH-initiated daytime reaction (3%).

Initial carbon-sulfur bond homolysis is believed to be implicated in the conversion of the spiro dihydrothiopyran (253) to the fluoranthene (254), as shown in Scheme 19.202 Loss of sulfur accompanied by the formation of a,/Lunsaturated aldehydes has also been observed on irradiation of the corresponding sulfoxide.203 An additional competing pathway, leading to... 

Mochida et al. studied the hydrogenation of fluoranthene (39) over carbon-sup-ported platinum metal catalysts in decalin at elevated temperatures and pressures.267 Fluoranthene was hydrogenated much more readily than pyrene, and was highly selective for the formation of tetrahydrofluoranthene 40 over all the catalysts investi-... 

Figure 5 The gas phase OH radical-initiated reaction of fluoranthene (a 3-ring PAH) in the presence of NOx. The reaction results in the formation of both hydroxy- and nitro-fluoranthene, although nitro-fluoranthene can also form from the nighttime reaction with the NO3 radical Reaction scheme adapted from Arey et al. ...

A typical structural feature of the crystalline radical-cation salts is the formation of stacks. Thereby, the hydrocarbon units are packed in columns leaving space for channels in which the closed-shell counterions are placed. The planar hydrocarbons are oriented perpendicularly to the stacking axes with interplanar distances between 0.32-0.33 nm which are significantly smaller than the van-der-Waals radii of the carbon centers and allow for strong w-orbital overlap. It is also characteristic that the molecules are alternately rotated by 180°, as e.g. in the fluoranthene salt [17,18]. Closed inspection shows also that a particularly strong interaction arises between r-centers which in the corresponding radical cation possess a high local spin density. 

As we accounted for the difficulties mentioned in ring-closures of fluorene derivatives (125) to fluoranthenes, the combinations of five- and six-membered carbon ring systems in a planar arrangement are associated with considerable angle strain. This obstacle should be cancelled out essentially in combinations of five- and seven-membered ring systems. The condensation products (170) and (172) of acenaphthenone and fluorene with (44) in the following examples indeed cyclize under relatively smooth conditions by formation of such systems47. ... 

The electric arc between titanium electrodes submerged in methanol was conducted according to the standard method given in Section 8.2.1. After 10 min arcing the polyyne solution obtained was filtered and injected into the HPLC-DAD column for analysis. The formation of carbon derived from the carbonization of the solvent was much less significant than in the previous experiment carried out in -hexane. In this case, no polyynes were detected even in trace amounts by HPLC analysis. Only a mixture of about 12 PAHs was obtained. Among them biphenyl, naphthalene, acenaphtha-lene, phenanthrene, anthracene, perylene, and fluoranthene were identified. 

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