The fluorescence spectrum of many polycyclic aromatic compounds (PACs) depends upon solvent polarity. The emission spectrum of PAC monomers consists of several major vibronic bands labeled I, II, etc., in progressive order. Emission intensity enhancement of select bands is observed in polar solvents.

In 1933, benzo[a]pyrene, a hydrocarbon, which was and still is of very great importance for cancer research, was isolated from coal tar and also was synthesized. In recent years more than 450 synthetic compounds have been found to be carcinogenic, and more than 200 are polycyclic aromatic hydrocarbons, their derivatives and analogues. Recently a new polynuclear hydrocarbon, a seven ring compound naphtho[2,1-a]perylene was synthesized in This Laboratory Physiological tests have revealed this compound to be a potent carcinogen. This experience has prompted a new initiative to prepare a number of related compounds of this type in order to bring further insight to the relation between chemical structure and the mechanism of physiological activity. During the synthesis of the four new seven fused aromatic ring systems and a new eight fused aromatic ring system, several modifications and improvement of existing synthetic procedures were made. A recently published modification of the Rosenmund-von Braun method of nitrile synthesis was successfully applied to the preparation of 2-(2-naphthylmethyl)benzonitrile. It was found that 2-(2-naphthylmethyl)phenyl-1-naphthyl ketone and 2-(2-naphthylmethyl)phenyl-2-naphthyl ketone could be prepared by the reaction of a Grignard reagent with a nitrile as well as by the inverse addition of a Grignard reagent to the appropriate acid chlorides. The alumina cyclodehydrogenation procedure was confirmed to be the, only method of synthesis that yields 12-(1-naphthyl)-benz[a]anthracene from its precursor ketone. The yield of 12-(2-naphthyl)benz[a]anthracene was increased from 61% to 83% when anhydrous hydrogen fluoride was used in place of 48% hydrogen bromide and glacial acidic acid as the cyclodehydration media of the precursor ketone. A new cyclodehydrogenation procedure was developed. This procedure, which employs a mixture of aluminum chloride-stannic chloride and alumina, was used to prepare a new hydrocarbon, naphtho[l,2-a]-perylene. An aluminum chloride-sodium chloride melt permeated with carbon dioxide was successfully employed in the preparation of naphtho[2,2-1]benzo- (a]pyrene, naphtho(l,2-l]benzo[a]pyrene, and naphtho- (2,3-1]benzo[a]pyrene. It was shown that high temperature gas chromatography with ionization detectors can be used with success to analyze all of the above discussed ketones, benz[a]anthracenes as well as the new perylene and pyrenes. Additional support of the validity of the. structures of naphtho[1,2-a]perylene and naphtho- [2,1-1]benzo[a]pyrene was provided when the cyclodehydrogenation of these hydrocarbons yielded one and the same product, naphtho[l,7,8-efg]anthanthrene. It was observed that the correlation between color and structure of the newly prepared hydrocarbons follows the principles of annelation. When the ultraviolet and visible spectra peak frequencies were compared it was found that the values and positions of the peaks follow the principles of the annelation method. The examination of the infrared absorption spectra revealed that naphtho[l,2-a]perylene, naphtho[2,1l-1]benzo[a]pyrene, naphtho[1,2-1]benzo[a]-pyrene, and naphtho[2,3-1]benzo[a]pyrene exhibited Peaks at all four, "solo," "duo," "trio," and "quartet", carbon-hydrogen vibration regions, but as expected naphtho[1,7,8-efg]anthanthrene had the "quartet" carbon-hydrogen peak missing between 770 and 755 cm. which further substantiated the validity of the naphtho[1,7,8-efg]anthanthrene structure. The TNF molecular adducts of the five newly prepared compounds, naphtho[1,2-a]perylene, naphtho- [2,1-1]benzo[a]pyrene, naphtho1l,2-1]benzo[a]pyrene, naphtho[2,3-1]benzo[a]pyrene, and naphtho[1,7,8-efg]-anthanthrene were prepared and their melting points recorded. In order to ascertain the structures of the naphtho[1,2-a]perylene and the naphtho[1,2-l]benzo[a]-pyrene obtained from the cyclodehydrogenation of 12-(1-naphthyl)benz[a]anthracene and 12-(2-naphthyl)-benz[a]anthracene, respectively, other routes of synthesis were undertaken. The hydrocarbon, 11-(1-naphthyl)benz[a]anthracene, was prepared by the reaction of 1-naphthylmagnesium bromide with 11-keto-5,6,8,9,10,11-hexahydrobenz[a]- anthracene which on distillation under reduced pressure gave 11-(1-naphthyl)-5,6,8,9-tetrahydrobenz[a]anthracene and on aromatization yielded 11-(1-naphthyl)benz[a]-anthracene. When 1-naphthyl magnesium bromide was allowed to react with the 11-keto-8,9,10,11-tetrahydrobenz[a]anthracene, 11-(1-naphthyl)-8,9~dihydrobenz[a]anthracene was obtained when distilled under reduced pressure. This, likewise, gave 11-(1-naphthyl)- benz[a]anthracene on aromatization. Naphtho[1,2-a]perylene was synthesized unequivocally from 11-(1-naphthyl)benz[a]anthracene via a cyclodehydrogenation reaction. The hydrocarbon, 1-(1-naphthyl)-1,2,3,4-tetrahydrobenz[a]anthracene, was prepared by the reaction of 1-naphthylmagnesium bromide with 1-keto-1,2,3,4- tetrahydrobenz[a]anthracene. On distillation under reduced pressure 1-(1-naphthyl)-1,2,3,4-tetrahydrobenz[a]anthracene was obtained. Under the conditions of an aromatization procedure, naphtho[1,2-1]benzo[a]-pyrene was obtained. The hydrocarbons 11-(1l-naphthyl)-5,6,8,9-tetrahydrobenz[a]anthracene, 11-(1-naphthyl)-8,9-dihydrobenz[a]anthracene, 11-(1-naphthyl)benz[a]-anthracene, 1-(1-naphthyl)-1,2,3,4-tetrahydrobenz[a]anthracene are additional new compounds. / Ph. D.

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Thesis advisor: Lawrence T. Scott / Thermal cyclodehydrogenation is the key step in the total synthesis of fullerene C60 and represents an important family of carbon-carbon bond-forming reactions. My research focuses on understanding the mechanism of C-C bond formation in the high temperature cyclodehydrogenations of PAHs using appropriate test cases to form 5- or 6-membered rings. My goal was to understand more about molecular reactions under extreme conditions and thereby realize new synthetic pathways for new molecules. This dissertation describes the synthesis of several substrates and studies of their thermal cyclodehydrogenations. Chapter 1 presents the cyclodehydrogenations of [5]helicene and benzo[5]helicene to form 6-membered rings under flash vacuum pyrolysis (FVP) conditions. An observed rate difference established that an electrocyclic mechanism is favored in this case and disproved the radical cyclization and 1,2-hydrogen shift/carbene insertion mechanisms. Chapter 2 describes the cyclodehydrogenations of phenyl-substituted phenanthrenes to form 6-membered rings under FVP conditions. The radical mechanism is ruled out because of the rate difference. Chapter 3 shows the synthesis of 7-(9H-fluoren-9-ylidene)-7H-benzo[c]fluorene and its thermal cyclodehydrogenation to form 6-membered rings under FVP conditions. In chapter 4, the cyclodehydrogenations of phenyl-substituted anthracenes and phenanthrenes to form 5-membered rings under FVP conditions are presented. The unexpected dominance of phenyl loss suggests that radical mechanisms are occurring during the cyclodehydrogenations. Chapter 5 describes the cyclodehydrogenations of [4]helicene and benzo[4]helicene to form 5-membered rings under FVP conditions. The results point to a carbene cyclization mechanism, in competition with the radical mechanism. / Thesis (PhD) — Boston College, 2008. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

Polycyclic aromatic hydrocarbons (PAHs) are an important class of persistent organic pollutants (POPs) that are commonly found in the environment at low concentrations. POPs are long-lived organic compounds and originate almost entirely from anthropogenic activities such as chemical industries, combustion and agriculture activities. Owing to their potential carcinogenicity, mutagenicity and teratogenicity, PAHs have been determined in several matrices, particularly water, soil and sediment. Hazards associated with these compounds are owing to their hydrophobic character, persistence and bioaccumulation properties of several individual PAHs. Hence the primary goal of this research was to identify and determine PAHs in water and sediment samples, from rivers and dams in greater Johannesburg area, South Africa. In this work, three extraction techniques have been optimized for the extraction of PAHs in various samples. The extraction techniques based on hollow fiber liquid phase microextraction (HF-LPME) and solid phase extraction (SPE) were optimized for aqueous samples. Microwave assisted extraction technique (MAE) was optimized for solid samples. The optimized methods were applied to real water and sediment samples in and around Johannesburg area. HF-LPME and SPE techniques were compared with each other, while MAE was compared with Soxhlet (SE) in terms of their extraction efficiencies, enrichment factors, detection limits, relative standard deviations and concentrations of PAHs found in real samples. HF-LPME technique involved extraction of PAHs from a 20 mL sample containing 20% acetonitrile as a modifier. The PAHs were extracted into a 5 cm hollow fibre filled with heptane as organic solvent. At a stirring speed and extraction time of 600 rpm and 30 minutes, respectively, the acceptor solvent was collected to be analysed by GC-MS. The obtained enrichment factors ranged from 40 to 95 and the recoveries ranged from 3-8% depending on individual PAHs. The detection limits ranged from 23.0-95.0 ng L-1 while relative standard deviations for the recoveries were less than 5%, (n=3). The concentrations obtained in real water samples ranged from 30.3-213.8 ng L-1 and the relative standard deviations were between 0.8-11.9%, (n=3). SPE technique involved extraction of PAHs from a 100 mL sample containing 10% methanol as a modifier. The PAHs were extracted using C18 cartridges with 40% methanol in water as conditioning solvents and 3 mL acetone: THF (1:1) as eluting solvents. After eluting, the analyte is reduced to 1 mL under nitrogen and then analysed using GC-MS. The obtained enrichment factors ranged from 78-135 depending on the individual PAH. The detection limits ranged from 20.0-52.0 ng L-1. The relative standard deviations for the obtained enrichment factors were less than 6%. The obtained concentrations from real water samples ranged from 21.4-615.7 ng L-1 and the relative standard deviations were between 1.9-13.0%, (n=3). In MAE technique, the extraction was carried out with 20 mL of hexane: acetone (1:1, v/v) mixture with 1 g sample at 250 W for 20 minutes. After extraction, the extract was cleaned and reduced to 1 mL under nitrogen and then injected into an HPLC-Fluoresence system. The obtained recoveries ranged from 61-98% depending on the individual PAHs. The detection limits obtained ranged from 0.03-0.5 μg L-1 for HPLC-Fluorescence. The relative standard deviations were less than 6% for the obtained enrichment factors. The obtained concentrations in the sediments ranged from 61-45281μg kg-1 and the relative standard deviations ranged from 2.1-10.8%, (n=3). The possible major sources of PAHs pollution in rivers and dams in great Johannesburg area was suspected to be due to poor wastewater and solid waste management in informal settlements and a large oil spill accident that happened. This is supported by the large concentrations of PAHs found in sediments from Jukskei River which passes through one of the largest informal settlements. The pH in this river is also basic with large conductivity suggesting the presence of anions. The recipient dam of this river had also problems of algae and weeds growing in it. The influence of oil spill that happened is supported by decreasing concentrations of PAHs in the sediments with distance away from the accident area in the Blaauwpan dam. Other possible sources of PAHs are vehicle emission since studies have shown that from about 2005, the number of these in high ways in the city have been increasing by about 15-20% per year.

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Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Thesis (M.S.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains ix, 41 p. : ill. Includes abstract. Includes bibliographical references (p. 39-41).