Copper Phthalocyanine Dye Immobilized on Magnetite Particles: An Efficient Adsorbent for Rapid Removal of Polycyclic Aromatic Compounds from Water Solutions and Suspensions

Abstract

Magnetite particles bearing covalently immobilized copper phthalocyanine dye (“blue magnetite”) were prepared and used for the isolation and/or removal of polycyclic dyes from water solutions and suspensions. Binding of these polycyclic dyes occurs by a chemical, equilibrated, and saturatable mechanism, following the Langmuir adsorption model. Nonspecific adsorption of dyes having nonplanar molecular structure was low. The values of maximum adsorption capacity were calculated. The bound dyes were only partially eluted from the adsorbent with methanol and methanol–concentrated ammonia solution (50/1, v/v).     

Directed Toward the Development of a Unified Structure Theory of Polycyclic Conjugated Hydrocarbons - From Benzenoids to Fullerenes

Abstract

Several new principles - periodic table set, excised internal structure, circumscribing, constant-isomer series, aufbau enumeration, leapfrogging, and a topological paradigm - have led to a further understanding of the structure/property relationships of polycyclic conjugated hydrocarbons.     

The Supercritical Fluid Extraction of Anthracene and Pyrene from a Model Soil: An Equilibrium Study

Abstract

Supercritical carbon dioxide (SC-CO₂) is used to extract two polycyclic aromatic hydrocarbons (PAHs), anthracene and pyrene, from a model soil at conditions ranging from 35 to 55 [ddot]C and 7.79 to 24.13 MPa. Equilibrium partition coefficients and Freundlich isotherm constants are determined for the two PAHs on white quartz sand and the model soil. The effect on equilibrium of additional water in the soil phase is also examined.     

CYCLOPENT[bc]ACENAPHTHYLENE: A PUTATIVE INTERMEDIATE ON THE PATHWAY FOR THERMAL CYCLODEHYDROGENATION OF PHENANTHRENE

Phenanthrene, the archetypal “bay region” polycyclic aromatic hydrocarbon (PAH), loses two hydrogen atoms when subjected to flash vacuum pyrolysis (FVP) at 1100 °C and suffers a major skeletal rearrangement to form pyracylene (1), along with 1-, 3-, and 4-ethynylacenaphthylene (2, 3, and 4, respectively). Evidence is presented that implicates cyclopenta[bc]acenaphthylene (7) as a key intermediate on the reaction pathway from phenanthrene to these four C₁₄H₈ products.     

Evaluating π-π-Interactions as a Method for Isolation of Polycyclic Aromatic Hydrocarbons from Solution

The polycyclic aromatic hydrocarbon (PAH), chrysene, was linked to the solid support TentaGel S-NH₂ via a linker by means of synthesis. The resulting product 4-(chrysene-1-yloxy)-N-(TentaGel S)butanamide (4) was then evaluated for its ability to isolate PAHs from solution by means of π-π-interactions.     

EFFECT OF HETEROATOMS ON PARTITIONING OF π-ELECTRONS IN RINGS OF CATAFUSENES

An earlier proposed method for assessing the π-electron content (EC) of rings of heteroatom–containing polycyclic conjugated molecules [Balaban et al., Polycyclic Aromatic Compounds/27 (2007) 51] is modified so that the effects of heteroatoms become additive. By means of this, relatively simple rules for the changes of the EC-values could be formulated in the case of catafusenes.     

Detection of Polycyclic Aromatic Hydrocarbons (PAHs) in Human Breast Milk

Abstract

Exposure to polycyclic aromatic hydrocarbons can result from numerous sources including dietary as well as environmental. Exposure to polycyclic aromatic hydrocarbons has been well-established through combustion sources, particularly coal-fired power plants, automobile and diesel exhaust emissions, and the burning of fossil fuels. In addition, exposure to polycyclic aromatic hydrocarbons occurs through the intake of tobacco smoke, both mainstream and sidestream, and this exposure potentially represents one of the highest concentrations of polycyclic aromatic hydrocarbons to which we can be exposed. The plethora of chemicals found in tobacco presents considerable problems when trying to assess biological exposures to single or multiple compounds since the interactions of each of the chemicals with each other may deter the detection of the previous compound. In addition other materials found in tobacco may mask selective detection of certain compounds thereby minimizing their quantitative and qualitative analysis in biological products exposed to tobacco.

Previous studies from our laboratory have focused on the detection and characterization of biological markers to aromatic hydrocarbons, particularly in the application of protein biomarkers. In addition, our research has focused on the characterization of biomarkers of tobacco related products during specific time frames of pregnancy ranging from early first trimester pregnancies to third trimester and delivery samples. In the present series of investigations, we investigated the application and utilization of breast milk as a biological marker of postdelivery exposure of neonates to polycyclic aromatic hydrocarbons.     

Organosilicon Polycyclic Copolymers of Bead-like Structure

Abstract

The reaction of catalytic dehydrocondensation of dihydroorganocyclotetra(hexa)siloxanes with dihy-droxyorganocyclotetra(hexa)siloxanes in the presence of platinochlorohydric acid of anhydrous powderlike caustic potassium has been studied.

High-molecular organosilicon polycyclic copolymers of the bead-like structure with cyclotetra- and cyclohexasiloxane fragments in the chain completely dissoluble in organic solvents were synthesized.

Reaction order, activation energies and dehydrocondensation rate constants were found. Thermogravimetric, thermomechanical and X-ray studies of the synthesized polymers were carried out.     

Indeno-Polycyclic Aromatic Hydrocarbons: A Versatile New Synthetic Route

Acylation of a polycyclic aromatic hydrocarbon (PAH) adjacent to a ring junction with 2-bromobenzoyl chloride followed by Flash Vacuum Pyrolysis (FVP) of the resulting bromoketone affords the corresponding indeno-annulated PAH. The new method is illustrated by syntheses of indeno[1,2,3-cd]pyrene (1) from pyrene and indeno[1,2,3-cd]fluoranthene (2) from fluoranthene. The formation of indeno[1,2,3,4-defg]chrysene (11) from FVP of 8-(2-bromobenzoyl)-fluoranthene (10), and as a secondary product from FVP of 3-(2-bromobenzoyl)fluoranthene (9), reveals the ability of phenyl groups to migrate around the periphery of a didehydro-PAH. Mechanisms involving reversible hydrogen atom transfers are proposed. Diacylation of fluoranthene with 2-bromobenzoyl chloride followed by FVP gives the previously unknown, nonplanar, nonalternant, C₂₈H₁₄ PAH diindeno[1,2,3,4-defg: 1,2,3-rs]chrysene (21) in just two steps.     

Attempted Synthesis of Bowl-Shaped Polycyclic Aromatic Hydrocarbons via Oxidative Electrocyclization. Products from the Dications of Dibenzo [g,p] chrysene,Tetrabenzo[5.5]fulvalene,and Diphenylmethylidenefluorene

Synthesis of diindeno[1,2,3,4-defg: 1′,2′,3′,4′-mnop]chrysene (1), a portion of the C₆₀ surface, was attempted through oxidative cyclization of tetrabenzo[5.5]fulvalene (2), dibenzo[gp]chrysene (3), and diphenylmethylidenefluorene (4) by SbF₅/SO₂CIF. Compounds 2 and 3 were oxidized to dications which then underwent a single cyclization to give precursors to 1. Compound 4 underwent two oxidative cyclizations to give a precursor to 1. AM1 calculations of the possible products from cyclization were consistent with preferential formation of the cyclized product with the lower ΔHf. Oxidative cyclization may offer a one-pot synthetic alternative for the preparation of unusual polycyclic aromatic hydrocarbons.     

SYNTHESIS AND THERMAL INTERCONVERSION OF 5-FLUOROACENAPHTHYLENE BY FLASH VACUUM THERMOLYSIS

Abstract

The utility of high-temperature gas-phase cyclisation reactions for the synthesis of fluorosubstituted cyclopenta-fused polycyclic aromatic hydrocarbons (PAHs) was illustrated by the synthesis of 5-fluoroacenaphthylene by flash vacuum thermolysis (FVT) of 1-ethynyl-5-fluoronaphthalene.

The experimental results suggest that monofluorinated PAHs can be used as model compounds to study thermal interconversion of their parent PAHs since, with fluorine as a label; ¹⁹ F-NMR is a valuable tool to characterize complex mixtures.     

Activation of PAH by Ozone Derived Oxidants: Results at Ambient Conditions1

Abstract

Particle bound polycyclic aromatic hydrocarbons (PAH) are converted to K-region oxides when exposed to the product stream from a gas phase reaction of ozone and tetramethylethylene (TME). Ozone alone does not give the oxides. Oxide formation requires an oxidant produced in the ozone-TME reaction. Likely candidates for the oxidant are the carbonyl oxide and the dioxirane. In separate experiments it has been shown that dimethyl-dioxirane can react with particulate bound PAH to give K-region oxides. These results support the hypothesis that ozone-alkene reactions in polluted atmospheres may contribute to the formation of mutagens in these atmospheres.     

Organosilicon Polycyclic Copolymers of Bead-like Structure

Abstract

Catalytic dehydrocondensation of dihydroorganocyclotetra(hexa)siloxanes with dihydroxyorganocyclotetra(hexa)siloxanes in the presence of platinochlorohydric acid on anhydrous powder-like caustic potassium has been studied. High-molecular weight organosilicon polycyclic copolymers with bead-like structure having cyclotetra- and cyclohexasiloxane fragments in the chain and completely insoluble in organic solvents were synthesized. Reaction order, activation energies and dehydrocondensation rate constants were found. Thermogravimetric, thermomechanical and X-ray studies of the synthesized polymers were carried out.     

From Overcrowded Polycyclic Aromatic Enes to Semifullerenes

Abstract

Overcrowded polycyclic aromatic enes (1), e.g., bi-9H-fluoren-9-ylidene (2) and bi-4H-cyclopenta[def]-phenanthren-4-ylidene (3) are potential starting materials for the preparation of bowl-shaped fragments of fullerenes. Semiempirical MNDO-PM3 calculations of C₂₆ H_n and C₃₀ H_n (n = 12,14,16) species 2–14 are used to analyze energetic and steric effects on the dehydrocyclization and isomerization reactions of these molecules. the out-of-plane bending and pyramidalization in these species are ascribed to intramolecular overcrowding in the fjord and cove regions and to strain introduced by C5 rings in the PAH skeleton. Oxidative photocyclization reactions on Z-2,2′-bridged derivatives of 2 and 3 are briefly outlined.     

Surface-Enhanced Raman Analysis of some Polycyclic Aromatic Dyes used in the Cosmetics and Food Industries

Abstract

The Surface-Enhanced Raman spectra of three important polycyclic aromatic dyes used in the food and cosmetic industries. Erythrosine, Eosine, and Phloxine, are recorded for the first time. The ability of the Surface-Enhanced Raman scattering techniques to detect these dyes at trace level is demonstrated. Such techniques minimize the fluorescence background in these highly fluorescing dyes, bringing out the Surface-Enhanced Raman Spectra features. The Normal Raman Spectra of erythrosine and phtalazine were also recorded and compared with their Surface-Enhanced Raman Spectra to illustrate the fluorescence suppression in Surface Enhanced Raman Spectra. The vibrational spectra features of the three dyes are discussed in terms of their molecular structure and the vibrations of the aromatic rings.     

Quantitative Analysis of PAH in Pitch by HPLC with Fluorescence Detector

Abstract

This communication evaluates alternate sample preparation, PAH extraction and different high performance liquid chromatography (HPLC) analytic techniques for the analysis of PAH in pitch. The HPLC response using fluorescence (Fl) and particle beam mass spectrometric detectors are compared. An analytical methodology is proposed which assures a repeatability better than 7% for the 14 PAH examined. The pitch sample is meticulously ground and the polycyclic aromatic hydrocarbons are solubilized with ultrasonic agitation in acetonitrile. The filtered extract is diluted and finally eluted in an analytical column with a fluorescence detector and optimized wavelength selection. Results will be presented comparing PAH levels for selected pitches supplied to the aluminium industry.     

The Use of Copper Immobilized on Silica for Compound Class Fractionation of Polycyclic Aromatic Compounds in Environmental Samples

Abstract

Copper immobilized on silica has been investigated as an adsorbent for the fractionation of polycyclic aromatic compounds (PACs) into different compound classes. an open column chromatographic packing based on copper (II) bound to a silica substrate was used as a means of subdividing the PACs into less complex groups of similar compound types. the process has been applied to the fractionation of PACs extracted from a marine harbour sediment, for which the complex mixture of PACs could be separated into three subgroups, the contents of which were: (1) polycyclic aromatic hydrocarbons (PAHs), alkylated PAHs, and thiophenes; (2) compounds containing pyrrole-type (sp ³-hybridized) nitrogen (carbazoles), and also quinones and other oxygen containing species; and (3) compounds containing pyridine-type(sp ²-hybridized) nitrogen (acridine and its homologues). the fractions thus obtained have been characterized by gas chromatography-mass spectrometry (GC-MS). Extracted mass spectra, obtained from the crests of GC-MS peaks observed in reconstructed single ion chromatograms of selected m/z values, enabled unambiguous identification of many of the minor components of the mixture.     

Preparation of Deoxynucleosides,Deoxynucleotides and Oligodeoxynucleotides Bearing Adducts of PAH Diol Epoxides at the N6 Position of Adenine

Abstract

Oligonucleotides bearing adducts of the diol epoxides of benzo[a]pyrene and other polycyclic aromatic hydrocarbons on the exocyclic amino group of adenine have been prepared in a regio and stereospecific manner. The strategy involves reversal of the electrophile-nucleophile relationship; the PAH is linked to the adenine nucleus via condensation of an aminotriol (derived from the diol epoxide) with 6?fluoropurine deoxyribonucleoside. This condensation is carried out after the fluoro nucleoside has been incorporated into the oligonucleotide, but while the oligomer is still immobilized on the solid matrix. The diastereomeric oligomers derived from (±)?anti?BPDE are readily separable by HPLC, thus circumventing the need for individual enantiomers of the diol epoxide.     

Use of the Semipermeable Membrane Device (Spmd) to Sample Polycyclic Aromatic Hydrocarbon Pollution In A Lotic System

Abstract

Relative concentrations of aqueous polycyclic aromatic hydrocarbons (PAH) were investigated in an urban creek. Samples were obtained at five sites within a 600-m segment of the creek that is critical habitat for an endangered species of fish. the sampling technique entailed immersion of semipermeable membrane devices (SPMDs) in the water for intervals as long as 64 d. SPMDs are passive, in situ, mtegrative samplers of bioavailable (truly dissolved) PAH and other hydrophobic organic contaminants. Two point sources of PAH to the 600-m segment of the creek were differentiated. Aqueous concentrations were found to wane dramatically over the relatively short section of the creek between the point sources. All samples were almost devoid of alkyl-substituted PAH, indicating that the ultimate sources were probably of pyrogenic nature.     

Determination of Averaged Long-term Air Concentrations of Semivolatile Polycyclic Aromatic Hydrocarbons: First Results

Abstract

Using our long-term sampling methodology presented previously, consecutive 14-day air samples of semivolatile polycyclic aromatic hydrocarbons (PAH) (from fluoranthene/pyrene to coronene) were collected over the time-span of nearly a whole year at a semi-rural site (Jülich) and quantified by GC-FID. As expected, concentrations were higher in winter [3 ng m^?3 for benzo[e]pyrene (BEP)] than in summer (0.4 ng m^?3 for BEP). However, normalized concentrations (to BEP =1) showed constant values for most PAH; thus, a largely stable PAH profile is obvious. Exceptions are benzo[a]pyrene and benz[a]anthracene: their concentrations normalized to BEP were lower in summer, indicating specific losses. Reasons for these losses are unknown as yet, although degradation reactions during atmospheric transport are a distinct possibility.