Polycyclic aromatic hydrocarbons isolates production

Even a cursory examination of the literature shows that analysis of virtually every environmental sample reveals contamination from polycyclic aromatic hydrocarbons — resulting from incomplete combustion processes — and a range of the more recalcitrant organohalogen compounds such as DDT (together with its degradation product DDE), PCBs, hexachlorocyclohexanes, compounds related to aldrin, and mixtures present in commercial toxaphene preparations. Possibly the most disturbing fact, which has already been noted, is the occurrence of these compounds in samples from remote and largely isolated locations in the Arctic and Antarctic. 

There are several reports this year of photocycloaddition reactions between polycyclic aromatic hydrocarbons and 1,3-dienes. Anthracene (58 R = H) or 9-cyanoanthracene (58 R = CN) give [4 -I- 4] and [4 -I- 2]adducts on irradiation with buta-1,3-diene, but the different product ratios and temperature effects are used to support the previously proposed biradical mechanism for the reaction. Another report from the same group deals with anthracene-hexa-2,4-diene and 9-phenylanthracene-penta-1,3-diene or cyclohexa-1,3-diene systems in the case of 9-phenylanthracene (59) and cyclohexa-1,3-diene, two [2 -I- 2]cycloadducts involving a terminal aromatic ring are isolated, as well as the more usual [4 + 2] and [4 -f- 4]adducts involving the central ring. Irradiation of substituted anthracenes... 

The epoxides of several polycyclic aromatic hydrocarbons have been prepared by the use of a large excess of oxidant in a bipha-sic Oxone-ketone system under neutral conditions, as shown for the oxidation of phenanthrene (eq 11). However, the use of isolated dioxirane solutions is more efficient for the synthesis of reactive epoxides, since hydrolysis of the product is avoided. A number of unstable epoxides of various types have been produced in a similar manner, as discussed for Dimethyldioxirane and Methyl(trifluoromethyl)dioxirane. 

Triphenylene (TP) derivatives have been described as the work horses in the field of DLCs [11]. It is the most studied discotic core system [20, 21]. TP (1), see Scheme 4.1, belongs to the polycyclic aromatic hydrocarbon (PAH) group and has been known in the chemical literature for more than a century. This trimer of benzene was isolated from the pyrolytic products of benzene by Schultz who named it as triphenylene [22]. It can also be isolated from coal tar. Trimerization of cyclohexanone followed by dehydrogenation has been used to generate TP in the early twentieth century and its various chemical and physical properties were studied [22]. 

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