Polycyclic Aromatic Ketones Research Articles

Aromatic terminology. Highlighting the keywords polycyclic aromatic hydrocarbons (PAHs) and polycyclic aromatic compounds (PACs)

AbstractThe present Review on aromatic terminology was prompted by a recent series of articles exploring the chemical space of polycyclic aromatic systems and introducing new related keywords. The keywords polycyclic aromatic hydrocarbons (PAHs) and polycyclic aromatic compounds (PACs) are highlighted. Keywords and other entities relevant to PAHs and PACs are outlined. The article calls the community of polycyclic aromatic hydrocarbons and polycyclic aromatic compounds to use these two leading keywords and their acronyms PAHs and PACs and the accompanying keyword benzenoid hydrocarbons, but to refrain from using and coining related new and previously proposed similar general keywords. This recommendation does not rule out keywords combining ‘polycyclic aromatic’ and a specific functionality, e.g., polycyclic aromatic ketones.

Co-pyrolysis mechanism of polyester enameled wire and PVC: A joint experimental and theoretical investigation

For the recovery of enameled wire, pyrolysis is a resource-friendly and effective process. However, because waste enameled wires are typically recovered from e-waste, a minor number of wires and cables are usually present. As a result, co-pyrolysis of the paint film and wire and cable sheaths is inevitable during the pyrolysis recovery of waste enameled wires. Polyethylene terephthalate (PET) polyester enameled wire and polyvinyl chloride (PVC) were chosen as representatives of enameled wire and cable sheath materials, respectively. The pyrolysis characteristics and pyrolysis kinetic parameters of enameled PET (EPET) wire paint, PVC, and Mixture (a mixture of the two materials, mEPET: mPVC = 9:1) were investigated using TG and various kinetic analysis methods. The combined pyrolysis index and Py-GC/MS were used to assess the co-pyrolysis of EPET and PVC and the products. The pyrolysis of EPET is adversely affected by the presence of PVC throughout the process; however, the presence of Cu in EPET may facilitate the HCl removal reaction of PVC. The co-pyrolysis products of EPET and PVC are more complex, and according to the different main functional groups, can be divided into monocyclic aromatic hydrocarbons, polycyclic aromatic hydrocarbons, phenols, ketones, aldehydes, alcohols, esters, carboxylic acids, chlorides, and others. Finally, density functional theory calculations were used to explore the co-pyrolysis mechanism of PET and PVC as well as the creation mechanism of various pyrolysis products. The catalytic mechanism of Cu contained in EPET on PET and PVC was explained from the perspective of electrostatic potential. This study provides a theoretical foundation and comprehensive reference for the pyrolysis and recycling of waste enameled wires.

Antiandrogenic and Estrogenic Activity Evaluation of Oxygenated and Nitrated Polycyclic Aromatic Hydrocarbons Using Chemically Activated Luciferase Expression Assays.

To establish the risk of the endocrine disrupting activity of polycyclic aromatic compounds, especially oxygenated and nitrated polycyclic aromatic hydrocarbons (oxy-PAHs and nitro-PAHs, respectively), antiandrogenic and estrogenic activities were determined using chemically activated luciferase expression (CALUX) assays with human osteoblast sarcoma cells. A total of 27 compounds including 9 oxy-PAHs (polycyclic aromatic ketones and quinones) and 8 nitro-PAHs was studied. The oxy-PAHs of 7H-benz[de]anthracen-7-one (BAO), 11H-benzo[a]fluoren-11-one (B[a]FO), 11H-benzo[b]fluoren-11-one (B[b]FO), and phenanthrenequinone (PhQ) exhibited significantly the potent inhibition of AR activation. All nitro-PAHs exhibited high antiandrogenic activities (especially high for 3-nitrofluoranthene (3-NFA) and 3-nitro-7H-benz[de]anthracen-7-one (3-NBAO)), and the AR inhibition was confirmed as noncompetitive for 3-NFA, 3-NBAO, and 1,3-dinitropyrene (1,3-DNPy). Antiandrogenic activity of 3-NFA demonstrated characteristically a U-shaped dose-response curve; however, the absence of fluorescence effect on the activity was confirmed. The prominent estrogenic activity dependent on dose-response curve was confirmed for 2 oxy-PAHs (i.e., B[a]FO and B[b]FO). Elucidating the role of AR and ER on the effects of polycyclic aromatic compounds (e.g., oxy- and nitro-PAHs) to endocrine dysfunctions in mammals and aquatic organisms remains a challenge.

Significance of Competitive Reactions in an Atmospheric Pressure Chemical Ionization Ion Source: Effect of Solvent.

Ionization of organic compounds with different structural and energetic properties including benzene derivatives, polycyclic aromatic hydrocarbons (PAHs), ketones, and polyenes was studied using a commercial atmospheric pressure corona discharge (APCI) ion source on a drift tube ion mobility-quadrupole-time-of-flight mass spectrometer (IM-QTOFMS). It was found that the studied cohort of compounds can be experimentally ionized via protonation, charge transfer, and hydride abstraction leading to formation of [M + H]+, [M]+•, and [M – H]+ species, respectively. By experimentally monitoring the product ions and comparing the thermodynamic data for different ionization paths, it was proposed that NO+ is one of the main reactant ions (RIs) in the ion source used. Of particular focus in this work were theoretical and experimental studies of the effect of solvents frequently used for analytical applications with this ion source (acetonitrile, methanol, and chloroform) on the ionization mechanisms. In methanol, the studied compounds were observed to be ionized mainly via proton transfer while acetonitrile suppressed the protonation of compounds and enhanced their ionization via charge transfer and hydride abstraction. Use of chloroform as a solvent led to formation of CHCl2+ as an alternative reactant ion (RI) to ionize the analytes via electrophilic substitution. Density functional theory (DFT) was used to study the different paths of ionization. The theoretical and experimental results showed that by using only the absolute thermodynamic data, the real ionization path cannot be determined and the energies of all competing processes such as charge transfer, protonation, and hydride abstraction need to be compared.

PM2.5 chemical composition and health risks by inhalation near a chemical complex

Particulate matter (PM2.5) samples were collected in the vicinity of an industrial chemical pole and analysed for organic and elemental carbon (OC and EC), 47 trace elements and around 150 organic constituents. On average, OC and EC accounted for 25.2% and 11.4% of the PM2.5 mass, respectively. Organic compounds comprised polycyclic aromatic hydrocarbons (PAHs), alkylated PAHs, anhydrosugars, phenolics, aromatic ketones, glycerol derivatives, aliphatic alcohols, sterols, and carboxyl groups, including aromatic, carboxylic and dicarboxylic acids. Enrichment factors > 100 were obtained for Pb, Cd, Zn, Cu, Sn, B, Se, Bi, Sb and Mo, showing the contribution of industrial emissions and nearby major roads. Principal component analysis revealed that vehicle, industrial and biomass burning emissions accounted for 66%, 11% and 9%, respectively, of the total PM2.5-bound PAHs. Some of the detected organic constituents are likely associated with plasticiser ingredients and thermal stabilisers used in the manufacture of PVC and other plastics in the industrial complex. Photooxidation products of both anthropogenic (e.g., toluene) and biogenic (e.g., isoprene and pinenes) precursors were also observed. It was estimated that biomass burning accounted for 13.8% of the PM2.5 concentrations and that secondary OC represented 37.6% of the total OC. The lifetime cancer risk from inhalation exposure to PM2.5-bound PAHs was found to be negligible, but it exceeded the threshold of 10-6 for metal(loi)s, mainly due to Cr and As.

Study of Thermal Behavior of Moxa Floss Using Thermogravimetric and Pyrolysis-GC/MS Analyses.

Moxa floss is a type of biomass used as the main combustion material in moxibustion, a therapy that applies heat from moxa floss combustion to points or body areas for treatment. Safety concerns regarding moxa smoke have been raised in recent years. Since moxa floss is the source material in moxibustion, its thermal behavior and pyrolysis products would be related to the products formed in moxa smoke. This work aims to understand the thermal behavior of moxa floss and investigate the pyrolysis products generated from moxa floss combustion. Six commercial moxa floss samples of 3 storage years and 10 storage years, and of low, medium, and high ratios, were selected. The kinetic data from moxa floss combustion was carried out by a thermogravimetric analyzer. Pyrolysis-gas chromatography and mass spectroscopy using a gas chromatograph and mass spectrometer equipped with a pyroprobe were used to examine the pyrolysis products. Thermogravimetric profiles for all the samples were overall similar and showed a monotonic weight decrease. The range of intensive reaction temperature occurred between 150°C and 450°C, which was characterized by a major weight loss and accompanied by an exothermal degradation of the main components. The average ignition temperature for the samples of 3 and 10 storage years was 218.3°C and 222.6°C, respectively, which was lower than most herbaceous plants. The identified pyrolysis products include monocyclic aromatic hydrocarbons, polycyclic aromatic hydrocarbons, ketones, acids, and alkanes. All were of relatively low intensities of below 5% in relative abundance. No volatiles were detected in the samples of 10 storage years. The relatively low values of ignition temperature suggested that moxa floss is more combustible and can be ignited more easily than other herbaceous plants. This may explain why moxa floss has remained as the preferred material used for moxibustion over the years.

A structural chemistry practitioner: a fox rather than a hedgehog. Reversibility of Friedel–Crafts acyl rearrangements

A retrospective review of reversibility revealed in Friedel–Crafts acyl rearrangements of polycyclic aromatic ketones derived from the polycyclic aromatic hydrocarbons naphthalene, phenanthrene, anthracene, fluorene, pyrene, and fluoranthene is presented. The reactions were carried out in polyphosphoric acid (PPA). A distinction is made between completely reversible reaction (equilibrium reaction) denoted by ⇌ and reaction, both directions denoted by ⇆. Reaction, both direction is considered reversible reaction, not completely reversible reaction. Gore’s 1955 proposition that Friedel–Craft acylation of reactive hydrocarbons is a reversible process has been verified. Complete reversibility has been revealed in ortho ⇌ para acyl rearrangements of fluorofluorenones (1FFL ⇌ 3FFL) and in dibenzofluorenones (DBahFL ⇌ DBbhFL). Both cases are intramolecular acyl rearrangements. The majority of reversible intramolecular and intermolecular Friedel–Crafts acyl rearrangements are formally “reaction, both directions,” e.g., dibenzoylpyrenes 1,6-Bz2PY ⇆ 1,8-Bz2PY. Acyl rearrangements and reversibility in Friedel–Crafts acylations are associated with thermodynamic control. However, sometimes kinetic control wins out over thermodynamic control. Polycyclic aromatic ketones in which the carbonyl group is coplanar with the aromatic nucleus may undergo Friedel–Crafts acyl rearrangements. The reversibility concept has been applied to the synthesis of new and known linearly annelated polycyclic aromatic ketones by intramolecular Friedel–Crafts rearrangements of their angularly annelated constitutional isomers. A linkage between reversible Friedel–Crafts acyl rearrangements in PPA and the Scholl reaction has been established in benzoylnaphthalenes and in dibenzoylpyrenes. As a structural chemistry practitioner, the scientific personality of the first author belongs to the foxes, rather than to the hedgehogs.

Dangerous organic chemicals identified in inhalable particulate matter air pollution

Inhalable particulate matter (PM10), comprising fine and thoracic coarse particulate matter (PM2.5 and PM10-2.5, respectively), is emitted from several sources. The sources includes construction and agricultural activities, transportation, industrial processes, power plants, wildfires, household solid cookfuels and suspensions or re-suspensions from unpaved roads, mining and natural sources. Previous studies, specifically from developed countries and China have shown that PM10 may contain several dangerous organic chemicals (DOCCs). However, very little is known about PM10 in developing countries. Therefore is study seeks to identify the DOCCs in airborne PM10 in Nagpur district, India. We collected 24-hr ambient PM10 samples from urban, peri-urban and rural areas of the district during wintertime (January, 2013). The DOCCs in the PM10 were identified by gas chromatography-mass spectrometry. The results revealed that polycyclic aromatic hydrocarbons (PAHs), chlorinated hydrocarbons, dioxins, furans, phthalate esters, aldehydes, ketones, phenols and organic acids are major DOCCs in the PM10. Quantitative analysis of thirteen individual PAHs in the PM10 revealed concentrations that greatly exceeded health-based guideline. This suggests that prolong inhalation of such PM10 may pose adverse risk to health of the population.

Tantala-based sol-gel coating for capillary microextraction on-line coupled to high-performance liquid chromatography

A sol-gel organic-inorganic hybrid sorbent, consisting of chemically integrated tantalum (V) ethoxide (TaEO) and polypropylene glycol methacrylate (PPGM), was developed for capillary microextraction (CME). The sol-gel sorbent was synthesized within a fused silica capillary through hydrolytic polycondensation of TaEO and chemical incorporation of PPGM into the evolving sol-gel tantala network. A part of the organic-inorganic hybrid sol-gel network evolving in the vicinity of the capillary walls had favorable conditions to get chemically bonded to the silanol groups on the capillary surface forming a surface-bonded coating. The newly developed sol-gel sorbent was employed to isolate and enrich a variety of analytes from aqueous samples for on-line analysis by high-performance liquid chromatography (HPLC) equipped with a UV detector. CME was performed on aqueous samples containing trace concentrations of analytes representing polycyclic aromatic hydrocarbons, ketones, alcohols, amines, nucleosides, and nucleotides. This sol-gel hybrid coating provided efficient extraction with CME-HPLC detection limits ranging from 4.41pM to 28.19 pM. Due to direct chemical bonding between the sol-gel sorbent coating and the fused silica capillary inner surface, this sol-gel sorbent exhibited enhanced solvent stability. The sol-gel tantala-based sorbent also exhibited excellent pH stability over a wide pH range (pH 0–pH 14). Furthermore, it displayed great performance reproducibility in CME-HPLC providing run-to-run HPLC peak area relative standard deviation (RSD) values between 0.23% and 3.83%. The capillary-to-capillary RSD (n=3), characterizing capillary preparation method reproducibility, ranged from 0.24% to 4.11%. The results show great performance consistency and application potential for the sol-gel tantala-PPGM sorbent in various fields including biomedical, pharmaceutical, and environmental areas.

Regioselective Friedel–Crafts deacylations of polycyclic aromatic ketones in the pyrene series

1,3,6,8-tetrabenzoylpyrene (1,3,6,8-Bz 4 PY) and 1,3,6-tribenzoylpyrene (1,3,6-Bz 3 PY) were synthesized and their crystal structures were determined. The Friedel–Crafts deacylations in PPA of 1,3,6,8-Bz 4 PY (at 120–200 °C) and of 1,3,6-Bz 3 PY (at 80–160 °C) have been studied. The mono-deacylation of 1,3,6-Bz 3 PY was regioselective and led to three dibenzoylpyrenes in the following order of relative amounts: 1,8-Bz 2 PY > 1,6-Bz 2 PY > 1,3-Bz 2 PY. 1,3,6,8-Bz 4 PY was resistant to deacylation at 120–160 °C. The deacylations of 1,3,6,8-Bz 4 PY at 200 °C gave the polycyclic aromatic ketone (PAK) 8H-dibenzo[def,qr]chrysen-8-one (DBCO) via an intramolecular Scholl reaction. Two plausible pathways of the Friedel–Crafts deacylation of 1,3,6,8-Bz 4 PY to give DBCO are proposed. A density functional theory (DFT) B3LYP/6-311(d,p) computational study of the conformational spaces of 1,3,6-Bz 3 PY and 1,3,6,8-Bz 4 PY was performed. The estimated energy barriers of formation of dibenzoylpyrenes by deacylation of 1,3,6-Bz 3 PY increase in the following order: 1,8-Bz 2 PY < 1,3-Bz 2 PY < 1,6-Bz 2 PY. A mechanism of the Friedel–Crafts deacylation of 1,3,6-Bz 3 PY in PPA via the respective O-protonated ketone and σ-complexes is presented.

Star-Shaped Polycyclic Aromatic Ketones via 3-Fold Cycloadditions of Isobenzofuran Trimer Equivalent.

Three-directional annulations of isobenzofuran trimer equivalent are developed. Importantly, the successive cycloadditions could be controlled under suitable conditions, selectively affording the dual or triple cycloadduct, which leads to the alternative preparation of the symmetrical and unsymmetrical star-shaped polycyclic aromatic ketones. 1H NMR analysis of the star-shaped aromatic ketone indicated the π-π interactions through the aggregation in solution.

Characterization of a pyrolysis liquid from a German brown coal by use of negative and positive ion mode electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry and collision-induced dissociation

A pyrolysis oil produced by slow pyrolysis from a German brown coal was analysed using a combination of three mass spectrometric methods. Various compounds of the pyrolysis liquid sample were ionized by electrospray ionization, both in positive (ESI(+)) and negative (ESI(−)) ion mode, and analysed by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). ESI(−)-FT-ICR-MS analyses mainly exhibit oxygen- as well as sulfur-/oxygen-containing compounds in the pyrolysis oil. In contrast, ESI(+)-FT-ICR-MS analyses were dominated by nitrogen- and nitrogen-/oxygen-containing species. Structural suggestions were possible by plotting the carbon number (nC) vs. the double bond equivalent (DBE). The assigned structures were further examined by applying ESI(−)-FT-ICR-MS with collision-induced dissociation mass spectrometry (CID-MS). The degradation of the pyrolysis oil constituents into their structural building blocks was monitored by varying the collision energy and its influence on the peak number and the median m/z. According to our results, dealkylation and decomposition processes of multiaromatic systems dominated during the CID event. Possible structural building blocks of pyrolysis oil S500 were found to be polycyclic aromatic ketones and quinones, partially bound to thiophenic structures. It was shown that the developed combination of ESI(+)- and ESI(−)-FT-ICR-MS with ESI(−)-CID-FT-ICR-MS gives the possibility to examine a complex sample, such as a pyrolysis liquid, by investigating its basic chemical backbone.

Silica- and germania-based dual-ligand sol-gel organic-inorganic hybrid sorbents combining superhydrophobicity and π-π interaction. The role of inorganic substrate in sol-gel capillary microextraction

Principles of sol-gel chemistry were utilized to create silica- and germania-based dual-ligand surface-bonded sol-gel coatings providing enhanced performance in capillary microextraction (CME) through a combination of ligand superhydrophobicity and π-π interaction. These organic-inorganic hybrid coatings were prepared using sol-gel precursors with bonded perfluorododecyl (PF-C12) and phenethyl (PhE) ligands. Here, the ability of the PF-C12 ligand to provide enhanced hydrophobic interaction was advantageously combined with π-π interaction capability of the PhE moiety to attain the desired sorbent performance in CME. The effect of the inorganic sorbent component on microextraction performance of was explored by comparing microextraction characteristics of silica- and germania-based sol-gel sorbents. The germania–based dual-ligand sol-gel sorbent demonstrated superior CME performance compared to its silica-based counterpart. Thermogravimetric analysis (TGA) of the created silica- and germania-based dual-ligand sol-gel sorbents suggested higher carbon loading on the germania-based sorbent. This might be indicative of more effective condensation of the organic ligand-bearing sol-gel-active chemical species to the germania-based sol-gel network (than to its silica-based counterpart) evolving in the sol solution. The type and concentration of the organic ligands were varied in the sol-gel sorbents to fine-tune extraction selectivity toward different classes of analytes. Specific extraction (SE) values were used for an objective comparison of the prepared sol-gel CME sorbents. The sorbents with higher content of PF-C12 showed remarkable affinity for aliphatic hydrocarbons. Compared to their single-ligand sol-gel counterparts, the dual-ligand sol-gel coatings demonstrated significantly superior CME performance in the extraction of alkylbenzenes, providing up to ∼65.0% higher SE values. The prepared sol-gel CME coatings provided low ng L−1 limit of detections (LOD) (4.2–26.3 ng L−1) for environmentally important analytes including polycyclic aromatic hydrocarbons, ketones and aliphatic hydrocarbons. In CME-GC experiments (n = 5), the capillary-to-capillary RSD value was ∼2.1%; such a low RSD value is indicative of excellent reproducibility of the sol-gel method used for the preparation of these CME coatings. The dual-ligand sol-gel coating provided stable performance in capillary microextraction of analytes from saline samples.

Photochemical products causing fluorescence enhancement for 6H-benzo[cd]pyren-6-one in de-aerated and pre-irradiated solutions

Polycyclic aromatic ketones emit very weak fluorescence, but their fluorescence is significantly enhanced by about one hundred times after preliminary irradiation of their degassed solution. To investigate the mechanism of such fluorescence enhancement, liquid chromatography/time-of-flight mass spectrometry measurements were performed for degassed methanol, ethanol, and acetonitrile solutions of 6H-benzo[cd]pyren-6-one (naphthanthrone), in which fluorescence enhancement had been induced. As a result, two kinds of photochemical products were identified as the substance causing fluorescence enhancement: they were produced by dehydrogenation and dehydration of adducts of a solvent molecule to naphthanthrone. On the basis of the findings, the mechanism of the fluorescence enhancement of naphthanthrone was discussed.Fluorescence enhancement; 6H-benzo[cd]pyren-6-one; Polycyclic aromatic ketones; Liquid chromatography-mass spectrometry; Photochemical reaction

Organic matter in sediment layers of an acidic mining lake as assessed by lipid analysis. Part II: Neutral lipids

Natural neutralization of acidic mining lakes is often limited by organic matter. The knowledge of the sources and degradability of organic matter is crucial for understanding alkalinity generation in these lakes. Sediments collected at different depths (surface sediment layer from 0 to 1 cm and deep sediment layer from 4 to 5cm) from an acidic mining lake were studied in order to characterize sedimentary organic matter based on neutral signature markers. Samples were exhaustively extracted, subjected to pre-chromatographic derivatizations and analyzed by GC/MS. Herein, molecular distributions of diagnostic alkanes/alkenes, terpenes/terpenoids, polycyclic aromatic hydrocarbons, aliphatic alcohols and ketones, sterols, and hopanes/hopanoids were addressed. Characterization of the contribution of natural vs. anthropogenic sources to the sedimentary organic matter in these extreme environments was then possible based on these distributions.With the exception of polycyclic aromatic hydrocarbons, combined concentrations across all marker classes proved higher in the surface sediment layer as compared to those in the deep sediment layer. Alkane and aliphatic alcohol distributions pointed to predominantly allochthonous over autochthonous contribution to sedimentary organic matter. Sterol patterns were dominated by phytosterols of terrestrial plants including stigmasterol and β-sitosterol. Hopanoid markers with the ββ-biohopanoid “biological” configuration were more abundant in the surface sediment layer, which pointed to higher bacterial activity. The pattern of polycyclic aromatic hydrocarbons pointed to prevailing anthropogenic input. Pyrolytic makers were likely to due to atmospheric deposition from a nearby former coal combustion facility. The combined analysis of the array of biomarkers provided new insights into the sources and transformations of organic matter in lake sediments.

Enrichment of oxygen-containing aromatics in an extract from Zhundong subbituminous coal

Zhundong subbituminous coal (ZSBC) was exhaustively extracted with isometric carbon disulfide (CDS)/acetone mixed solvent to afford extract 1 (E 1 ), which was sequentially extracted with petroleum ether (PE) and CDS to afford extracts 2 (E 2 ) and 3 (E 3 ). E 3 was gradiently eluted into effluent portions 1 to 5 (EPs 1 to 5) through a silica gel-packed column sequentially with PE, CDS/PE mixed solvents with volume ratio of 3:7, 1:1 and 7:3, and CDS. According to analysis with a gas chromatography/mass spectrometer, in total, 22 alkyl phenyl carbonates were enriched into EP 3 , and anthraquinone and its two derivatives, nine polycyclic aromatic ketones and two polycyclic aromatic lactones into EP 4 . Most of the oxygen-containing aromatics are value-added chemicals.

Characterization of AhR agonist compounds in roadside snow

Aryl hydrocarbon receptor (AhR) agonistic contaminants were identified in roadside snow samples. Snow was collected in Oslo, Norway, and compared to a background sample collected from a mountain area. The water and particulate fractions were analysed for AhR agonists using a dioxin-responsive, chemically activated luciferase expression (CALUX) cell assay and by gas chromatography coupled to high-resolution time-of-flight mass spectrometry with targeted analysis for polycyclic aromatic hydrocarbons (PAHs) and broad-spectrum non-target analysis. The AhR agonist levels in the dissolved fractions in the roadside samples were between 15 and 387 pg/L CALUX toxic equivalents (TEQ(CALUX)). An elevated AhR activity of 221 pg TEQ(CALUX) per litre was detected in the mountain sample. In the particle-bound fractions, the TEQ(CALUX) was between 1,350 and 7,390 pg/L. One possible explanation for the elevated levels in the dissolved fraction of the mountain sample could be the presence of black carbon in the roadside samples, potentially adsorbing dioxin-like compounds and rendering them unavailable for AhR interaction. No polychlorinated dibenzodioxins and dibenzofurans or polychlorinated biphenyls were detected in the samples; the occurrence of PAHs, however, explained up to 9 % of the AhR agonist activity in the samples, whilst comprehensive two-dimensional gas chromatography coupled to mass spectrometry GCxGC-ToF-Ms identified PAH derivatives such as polycyclic aromatic ketones and alkylated, nitrogen sulphur and oxygen PAHs in the particle fractions. The (large) discrepancy between the total and explained activity highlights the fact that there are other as yet unidentified AhR agonists present in the environment.

P -メチレンキノン構造によって拡張した縮環型芳香族ケトンの合成と構造・物性

p -メチレンキノン構造によって拡張した縮環型芳香族ケトンの合成と構造・物性

High-temperature solvent stability of sol–gel germania triblock polymer coatings in capillary microextraction on-line coupled to high-performance liquid chromatography

Germania-based sol–gel organic–inorganic hybrid coatings were prepared for on-line coupling of capillary microextraction with high-performance liquid chromatography. For this, a germania-based sol–gel precursor, tetra- n-butoxygermane and a hydroxy-terminated triblock copolymer, poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) were used. These sol–gel germania triblock polymer coatings were chemically anchored to the inner walls of a fused silica capillary (0.25 mm I.D.) in course of its evolution from the sol solution. Scanning electron microscopy images of the sol–gel germania triblock polymer coating were obtained to estimate the coating thickness. For the first time, the analyte distribution constants between a sol–gel germania organic–inorganic hybrid coating and the samples ( K cs) were determined. For a variety of analytes from different chemical classes, including polycyclic aromatic hydrocarbons (PAHs), ketones, alcohols, phenols and amines, the K cs values ranged from 8.1 × 10 1 to 5.6 × 10 4. Also, for the first time, the stability of the sol–gel germania-based coating in high-temperature reversed-phase solvent environment was evaluated. The sol–gel germania triblock polymer coatings were capable of surviving exposure to high-temperature solvent conditions (200 °C) with little change in extraction capabilities. This demonstrates that sol–gel germania triblock polymer hybrid materials might be suitable for further applications in high-temperature HPLC. The reproducibility of the method for preparation of the sol–gel germania triblock polymer coatings was also evaluated, and the capillary-to-capillary RSD values ranged from 5.3 to 6.5%. The use of higher flow rates in extraction was found to significantly reduce the time required (from 30–40 to 10–15 min) to reach equilibrium between the sol–gel germania triblock polymer coating and the analytes in the sample solution.

Reversible Friedel-Crafts Acylations of Anthracene: Rearrangements of Acetylanthracenes

Treatment of 1-acetylanthracene (1-AcAN) and 9-acetylanthracene (9-AcAN) with PPA at 80-120 °C leads to the nearly complete conversion of these isomers into 2-acetylanthracene (2-AcAN), an illustration of the Agranat-Gore rearrangement of polycyclic aromatic ketones (PAKs). Ab initio MP2/6-31(d) calculations predict the following order of stabilities: for -complexes: 9-AcAN > 1-AcAN > 2-AcAN; for ketones: 2-AcAN > 1-AcAN > 9-AcAN; for O-protonated ketones: 2-AcAN > 1-AcAN > 9-AcAN. Thus, 9-AcAN is the kinetically controlled product, whereas 2-AcAN is the thermodynamically controlled product. No reverse rearrangements of 2-AcAN to either 9-AcAN or 1-AcAN and of 1-AcAN to 9-AcAN were observed. The results strengthen the pattern of reversibility in Friedel-Crafts acylations of PAHs. Keywords: Friedel-Crafts acetylation, PPA, Overcrowding, Agranat-Gore rearrangement, Deacylation, Ab initio calculations