Benzo chrysene calculations

FIGURE 9.64 Plot of logKp for 10 PAHs in ambient air samples collected at seven sites worldwide as a function of calculated values of log KI)A. FLE fluorene, PH phenanthrene, AN anthracene, PY pyrene, FL fluoranthene, BaA benz a anthracene, CHR chrysene, BaP benzo a pyrene, BeP benzo e pyrene, BkF benzo k fluoranthene (adapted from Finizio ei al., 1997). 

Anthracene and phenanthrene are isomeric compounds with three fused benzene rings. Their resonance energies are calculated to be 84 kcal/niol (352 kJ/mol) and 92 kcal/mol (385 kJ/mol), respectively. Many other polycyclic aromatic hydrocarbons are known. Chrysene and benzo[a]pyrene are typical examples. 

The retention indices were calculated as previously described by Popl et al. (45), with the hydrocarbon standards being assigned the following retention indices benzene, 10 naphthalene, 100 phenanthrene, 1000 benzanthracene, 10,000 and benzo[b]chrysene, 100,000. The retention index of an aromatic hydrocarbon was then calculated in a manner analogous to the calculation of Kovats indices for gas chromatography. 

Figure 26 illustrates the most similar pairs of benzenoids having perimeter P = 18. The similarity ofbenzo[c]phenanthrene (4)-triphenylene (5) and benzanthracene (2)-chrysene (3) was mentioned earlier benzanthracene (2)-benzo[a]pyrene (6) are another such pair the similarity of which is apparent from visual inspection. However, the high similarity of [interatomic separations, the descriptor that is critical in calculating their profiles. Hence, the most similar structures need not necessarily show apparent similarity. This is not the failure of the approach or the failure of the characterization of molecules but is a consequence of difficulties in separating different criteria when comparing structures. Our visual comparison is more likely to capture details of the contours of the molecule rather than an intrinsic property such as the interatomic separations. 

The limit of 1 mg PAU per 1 kg of dry soil was exceeded at more samples (T3 - T9, C3 and C5) in the assessment according to the U.S. EPA (U. S. EPA. 2007). The HQ values are higher, the maximal value is 5,2 in the T7 sample. The determined concentrations of chrysene in soil were compared with the limit values according to the Decree (Ministry of the Envi-romnent of the Czech Republic. 1996). The calculated HQ values reached the maximal value of 61,5 in the T6 sample. However, chrysene belongs to the least toxic PAH with Toxicity Equivalency Factor (TEF) 0,001, as opposed to benzo(a)p3uene (BaP), the TEF of which is 1. 

The enthalpies of the formal reaction for transforming a condensed benzenoid to the corresponding C2-interpolated [TV] phenylene using the experimental enthalpies of formation for naphthalene, phenan-threne, chrysene and biphenylene and the calculated enthalpies of formation for 54 and 55 were the nearly constant ca. 267 kj/mol. From the extensive [A/ -phenylene enthalpies of formation provided and the enthalpies of formation in Table 1, the enthalpies of reaction of other cata- and peri-condensed hydrocarbons are (kJ/mol) as follows anthracene, 260 triphenylene, 260 benzo[cjphenanthrene, 259 benz-[a]anthracene, 259. From our derived enthalpies of formation for naphthacene and picene, the reaction enthalpies are 260 and 268 kJ/mol, respectively, demonstrating the plausibility of our estimates. 

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