Sulfur-containing Polycyclic Aromatic Compounds Research Articles

Significant influence of different sulfur forms on Sulfur-containing polycyclic aromatic compound formation in high-sulfur coals

Sulfur-containing polycyclic aromatic compounds (SPACs) are important compounds found in coal. Previous research suggests that sulfur content is the most important controlling factor for SPAC formation. However, different forms of sulfur occur in coal. To study the influences of different sulfur forms on SPAC-formation mechanisms, six samples collected from the No. 14 coal seam of the Yuzhou Coalfield were identified to be high-pyrite sulfur coal (HPSC). Ten samples collected from the No. 11 coal seam from the Yuzhou Coalfield were identified to be high organic-sulfur coal (HOSC). Four samples collected from the No. 15 coal seamof the Dengfeng Coalfield were identified to be high sulfate-sulfur coal (HSSC). The study of the influences of different sulfur forms on SPAC-formation may better understand SPAC-formation mechanism.The collected samples were investigated using a microscope and organic geochemical methods. The microscopic findings revealed that the three coals have similar random vitrinite reflectance (Rr) values and have undergone similar geothermal processes. The geochemical results showed that the SPAC species and their contents in the HPSC, HSSC, and HOSC samples are very different. The HOSC samples of the No. 11 coal seam contained 65 SPACs; however, the HPSC samples of the No. 14 coal seam contained only 25 SPACs, and the HSSC samples of the No. 15 coal seam contained 44 SPACs. The average ratio of total-SPAC/total-PAC (T-SPAC/T-PAC) reaches 55.0 wt% in the HOSC samples, whereas the ratio is only 19.3 wt% in the HPSC samples, and 22.6 wt% in the HSSC samples. Coal maturity should not be a factor in the SPAC discrepancy because the three coal seams herein underwent similar geothermal processes. The sulfur forms may explain the apparent discrepancy of SPACs. Compared to the other two types of coal, the contents of pyrite, sulfur, and iron (Fe) are much higher in HPSC, and sulfur prefers to react with Fe to form pyrite, resulting in a lower SPAC content in HPSC and HSSC.The sulfur forms were influenced by the peat/coal-forming environments, which were affected by storm events. Finally, possible comprehensive formation pathways for major SPAC species have been proposed.

Origin and geological implications of super high sulfur-containing polycyclic aromatic compounds in high-sulfur coal

Polycyclic aromatic compounds (PACs) are ubiquitous in fossil fuels. As the main component of PACs, sulfur-containing polycyclic aromatic compounds (SPACs) have been widely studied because of their biological markers and maturity indicator functions. SPAC content is especially high in high-sulfur coal. However, the origin and formation of SPACs remain debatable. Herein, we discuss the origin and geological implications of abnormally enriched SPACs in high-sulfur coal of the Heshan Coalfield, Southern China.Fifteen coal and 6 parting samples were collected from the nos. 41 and 42 coal seams of the Heshan Coalfield, Guangxi Zhuang Autonomous Region, Southern China. Heshan coal is a superhigh organic sulfur coal (SHOSC). These collected samples were investigated using a microscope and organic geochemical methods. The microscopic results indicated that the random vitrinite reflectance (Ro) was 1.88% and 1.75% in the 41 and 42 coal, respectively. The dominant fractions of the extract were aromatic fractions with an average ratio of 79.62% in the 41 and 86.22% in the 42 coal samples, respectively, and 72.70% in the parting samples. Detailed quantification of the PACs was performed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC–MS). Seventy SPAC species were identified. The highest ratio of total SPAC/total PAC reached 89.22 wt% in the coal and 83.07 wt% in the parting samples. Such high SPACs are attributed to high sulfur, depositional environment, and organic matter thermal evolution. SPAC species and contents were initially controlled by the sulfur content, but gradually modified by the maturity of the organic matter. In addition, possible comprehensive formation pathways for major SPAC species have been proposed.

Limitations to GC-MS Determination of Sulfur-Containing Polycyclic Aromatic Compounds in Geochemical, Petroleum, and Environmental Investigations

A liquid chromatographic separation of polycyclic aromatic sulfur heterocycles (PASHs) from the polycyclic aromatic hydrocarbons (PAHs) is recommended to avoid interferences from the PAHs to ensure that the PASH determination is reliable when gas chromatography with mass-selective detection is employed. Examples are included that show that this separation also allows the PAHs to be analyzed correctly without interference of the PASHs. Sulfur aromatic compounds are frequently determined in geochemical investigations of crude oils, source rocks, and environmental samples and are used as markers for many properties of petroleum such as indicators for source rocks (carbonate vs siliciclastic) and maturity. Some interferences discussed here have been described previously, but the extent and consequences of them seem not to have found as much attention in practical work as would be expected. The step suggested involves a fast separation on a Pd(II)-containing stationary phase that allows the PASHs to be collected in a separate fraction that can be analyzed without interferences using any gas chromatographic detector. Examples are shown based on an Egyptian crude oil and standard reference material SRM 1580 shale oil.

Synthesis of Polysubstituted Benzothiophenes and Sulfur‐Containing Polycyclic Aromatic Compounds via Samarium Diiodide Promoted Three‐Component Coupling Reactions of Thiophene‐2‐carboxylate.

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Synthesis of polysubstituted benzothiophenes and sulfur-containing polycyclic aromatic compounds via samarium diiodide promoted three-component coupling reactions of thiophene-2-carboxylate.

By the promotion of samarium diiodide, thiophene-2-carboxylate reacted with 2 equiv of ketones at the C-4 and C-5 positions to give diols such as 2 and 9. Because the intermediary organosamarium species were oxophilic but not too basic, the double hydroxyalkylations with various ketone substrates, including alkyl aryl ketones, acetylthiophenes, cyclohexanone, alpha-tetralone, and alpha-phenylacetophenones, were realized without complication of side reactions. The diol products underwent an acid-catalyzed dehydration to give dienes such as 3 and 10, which were treated with DDQ to give either polysubstituted thiophenes (e.g., 4 and 11) or benzothiophenes (e.g., 5, 13, and 14) depending on the reaction conditions. Oxidative annulations of 4,5-diarylthiophenes 11 and 4,5,6,7-tetraphenylbenzothiophenes 14 were carried out by photochemical or chemical methods to give the sulfur-containing polycyclic aromatic compounds, such as phenanthro[9,10-b]thiophene-2-carboxylate, piceno[13,14-b]thiophene-2-carboxylate, and tribenzo[fg,ij,rst]pentapheno[15,16-b]thiophene-2-carboxylates. This method is applicable to the preparation of polysubstituted thiophenes, benzothiophenes, and the related compounds possessing liquid crystalline, photochromic, and other functional properties.

An evaluation of the mutagenicity, metabolism, and DNA adduct formation of 5-nitrobenzo[b]naphtho[2,1-d]thiophene.

Thioarenes, sulfur-containing polycyclic aromatic compounds, are environmental contaminants suspected of posing human health risks. In this study, 5-nitrobenzo[b]naphtho[2,1-d]thiophene (5-nitro-BNT), a nitrated-thioarene, was examined for its mutagenicity, metabolism and subsequent formation of DNA adducts. 5-Nitro-BNT was weakly mutagenic in Salmonella typhimurium strains TA98 and TA100 without Aroclor-1254-induced rat liver S9 (S9), and its activity was increased in the presence of S9. Anaerobic metabolism of 5-nitro-BNT by S9 or xanthine oxidase (XO) produced one major metabolite, identified as 5-amino-BNT by NMR, MS, and UV spectroscopy and by comparison with an authentic standard. Aerobic S9 metabolism of 5-nitro-BNT produced a major metabolite, identified as trans-9,10-dihydroxy-9,10-dihydro-5-nitro-BNT (5-nitro-BNT-9,10-diol). Also present was a minor amount of 5-amino-BNT and trans-9,10-dihydroxy-9,10-dihydro-5-amino-BNT (5-amino-BNT-9,10-diol). DNA adduct analyses were performed using the (32)P-postlabeling assay and reversed-phase HPLC. Three major XO-derived calf thymus DNA adducts were detected. On the basis of their chromatographic mobilities, two adducts were identified as reaction products of 5-nitro-BNT with 2'-deoxyguanosine and one adduct with 2'-deoxyadenosine. Incorporation of allopurinol (a specific XO inhibitor) in the incubation mixture resulted in loss of all three adducts, confirming enzymatic mediation by XO. Aerobic S9 activation of 5-nitro-BNT with calf thymus DNA produced three adducts. On the basis of their chromatographic mobilities, two were identified as reaction products of 5-nitro-BNT with 2'-deoxyguanosine and one with 2'-deoxyadenosine. Incorporation of 1-aminobenzotriazole (a P450 inhibitor) in the incubation mixture resulted in a loss of these adducts, confirming enzymatic mediation by P450. Aerobic S9-catalyzed metabolism of 5-nitro-BNT-9,10-diol produced the same DNA adducts as observed with 5-nitro-BNT. Aerobic S9-catalyzed metabolism of 5-amino-BNT-9,10-diol produced the same deoxyadenosine-derived DNA adducts as observed with 5-nitro-BNT and 5-nitro-BNT-9,10-diol. These results provide additional information that both ring oxidation and nitroreduction are involved in the metabolism, DNA adduct formation and mutagenicity of 5-nitro-BNT.

Isolation and Characterization of Sulfur-Containing Polycyclic Aromatic Compounds (Thia-Arenes) from Complex Environmental Mixtures

A multi-dimensional chromatographic method was developed and applied to the separation of thia-arenes and polycyclic aromatic hydrocarbons (PAH) derived from coal tar. A thia-arene-rich fraction, prepared using a combination of alumina chromatography and palladium chloride/silica gel chromatography, was further separated using normal phase HPLC to isolate fractions containing thia-arenes with molecular masses ranging from 184 amu to 284 amu. These fractions were analysed using gas chromatography-mass spectrometry; approximately one-half of the thia-arenes in a coal tar extract were retained and separated by the palladium chloride-silica gel step. This methodology has been successfully applied to coal tar, air particulate material, sediments and biological samples.

Use of the Zebra Mussel (Dreissena polymorpha) as a Bioindicator for Aromatic Hydrocarbons in Hamilton Harbour

Abstract Three methods for the extraction of polycyclic aromatic hydrocarbons (PAHs) from zebra mussels (Dreissena polymorpha) sampled from Hamilton Harbour were compared. Replicate freeze-dried mussel tissue samples were extracted using acid digestion, tissue homogenization (mechanical extraction) and ultra-sonication. Each extract was submitted to a cleanup procedure (alumina chro-matography and Sephadex LH20 gel chromatography), followed by analysis using gas chromatography-mass spectrometry (GC-MS). The three extraction methods were equally efficient, based on a statistical comparison of mean concentrations of individual PAHs. Mussel extracts, when subjected to bioassays with Salmonella typhimurium strain YG1029 (TA100-like) in the presence of an exogenous metabolic activation system (S9), exhibited significant mutagenic responses; these responses varied with the PAH content of the mussel extracts. Sources of PAHs in mussel extracts were determined by examining the profiles of sulfur-containing polycyclic aromatic compounds (thia-arenes). Comparison of the ratios of certain thia-arenes with ratios in source samples enabled identification of vehicular emissions and coal tar-contaminated sediment as two sources of PAH contamination in Hamilton Harbour.

Determination of polycyclic aromatic sulfur heterocyclic compounds in airborne particulate by gas chromatography with atomic emission and mass spectrometric detection

An analytical method is presented for the determination of tetra-, penta- and hexacyclic aromatic sulfur heterocyclic compounds (thiaarenes) in workplace air. Using a clean-up procedure for the isolation of polycyclic aromatic hydrocarbons and high-resolution gas chromatography with atomic emission detection, selective detection of thiaarenes was possible in the presence of abundant homocyclic aromatic hydrocarbons. Applying the method to an indoor air sample from an aluminium melting facility, more than 130 sulfur-containing components were detectable of which 53 components were identified as thiaarenes. Quantification of all identified thiaarenes by using one internal standard was possible due to the compound independent sulfur response of an atomic emission detector. The summarized concentration of all sulfur-containing polycyclic aromatic compounds isolated was found to be 12 μg/m 3.

Determination of Sulfur-Containing Polycyclic Aromatic Compounds in Coal Extracts using Capillary Column Gas Chromatography with Radio Frequency Plasma Detection

Abstract Detailed identification of sulfur-containing polycyclic aromatic compounds (S-PAC) was accomplished for solvent extracts of five different coals. The S-PAC were isolated by ligand-exchange chromatography. Due to the great complexities of these samples, capillary gas chromatography (GC) was employed for their analysis. An element selective radio frequency plasma detector was used to provide sulfur selective detection. Gas chromatography-mass spectrometry was used to identify individual compounds in isolated sulfur fractions. Condensed thiophenic compounds were found to be the major constituents in all five S-PAC fractions. Diaryl sulfides were also detected in the high volatile bituminous Illinois #6 coal. The prevalence of various S-PAC in different coal extracts was observed as a function of their rank.

Characterization of sulfur-containing polycyclic aromatic compounds in carbon blacks.

Characterization of sulfur-containing polycyclic aromatic compounds in carbon blacks.