Aromatic Sulfur Compounds Research Articles

Electronic structures of some aromatic sulfur compounds

The He(I) photoelectron spectra of the annelated thiophenes 1– 7 and the diarylsulfide 8 are reported. Based on MNDO calculations, the ionization potentials have been assigned to molecular orbitals. The electronic structure is discussed according to the molecules —in—molecules approach. The theory that the sulfur atom behaves like a carbon-carbon double bond is confirmed by the correlation of the π ionizations of 1– 4 with that of their carbocyclic counterparts. The conformational properties of 5 and 6 were investigated by MNDO calculations, indicating twisted conformations. In the photoelectron spectra no indications for conformational mixtures of 5 or 6 are present.

Photochemical transformations of selected organic chemicals in two phase system

The photodegradation of some aromatic sulfur compounds dissolved in n‐hexane and spread as a thin liquid film on water was investigated. Dibenzothiophene and diphenylsulfide were found to be the most reactive towards photooxidation process among the compounds studied. The degraded compounds were investigated by HPLC and GC/MS.

Formation of an unusual MH− ion in the methane negative-ion chemical ionization mass spectra of chlorprothixene and aromatic sulfur compounds

The methane negative-ion chemical ionization (NCI) mass spectrum of chlorprothixene shows an unusual MH− ion. This ion can be accounted for by electron capture followed by H˙ transfer from the reagent gas. The most probable site of electron attachment was concluded to be related to the sulfur atom of the thioxanthene ring based on the observation of analogous ions for structurally related compounds, all containing a heterocyclic sulfur. The MH− ion observed with methane as the reagent gas was shifted to MD− when tetradeuteromethane was used in place of methane. The ratio of [M H]− to MH− did not change with emission current suggesting that the process is independent of the radical concentration in the CI plasma. Consistent with this observation is the lack of CH3˙ or C2H5˙ adduct ions in the NCI mass spectrum and the fact that gold-plating the ion source did not decrease the proportion of MH−. Also, this mechanism is consistent with thermochemical considerations of reactions of a phenyl radical with various alkanes and observations of ions formed by methane NCI from model compounds. Therefore, unlike other MH− ions observed in methane NCI mass spectra, the mechanism of formation does not appear to involve a hydrogen radical addition followed by electron capture.

The Desulfurization of Polynuclear Aromatic Sulfur Compounds with a Raney Nickel

Abstract The mechanism of the desulfurization of the polynuclear thiophene compounds with a Raney nickel was studied in ethanol at atmospheric pressure and from 0 to 78.3 °C. The desulfurization rate was initially fast but reached zero in about 30 minutes. The major products were biphenyl in the desulfurization of dibenzothiophene (1), 1-phenylnaphthalene in the desulfurization of benzo[b]naphtho[1,2-d]thiophene (2), and 2-phenylnaphthalene in the reaction of benzo[b]naphtho[2,3-d]thiophene (3) and benzo[b]naphtho[2,1-d]thiophene (4). The desulfurization extent for the four compounds decreased in this sequence: 3>1>2>4. The extent of the desulfurization of the polynuclear thiophene compound was not related to the reaction indices, Fr(E), Fr(N), and Fr(R), of the sulfur atom of the compounds, which were calculated by using a simple Hückel theory; rather, it was related to both the free valence and the π-electron density. Therefore, the polynuclear thiophene compounds were considered to adsorb on a Raney nickel through the free-electron pair of the sulfur atom; consequently, the adsorption led to the C–S bond scission.

Liquid chromatographic determination of planar aromatic sulphur compounds in crude oil

Oxydation des dibenzothiophenes en sulfones et analyse par chromatographie liquide haute performance

Aromatic sulfur compounds other than condensed thiophenes in fossil fuels: enrichment and identification

A rapid and simple method has been established for the isolation of condensed thiophenes (PASH) and other types of aromatic sulfur compounds (S-PAC) based on ligand-exchange chromatography (LEC). This procedure has been applied to the aromatic fractions of a crude oil, a coal extract, and a hydrogenated coal liquid to obtain PASH and S-PAC fractions. Both fractions were examined by capillary column gas chromatography with flame ionization and flame photometric detection and by gas chromatography/mass spectrometry. A variety of previously unidentified S-PAC were found in these samples. Alkyl phenyl disulfides were the major S-PAC in the crude oil, and alkylphenylthiophene and propyl naphthyl sulfide were found in the coal extract, while alkyldihydrobenzothiophenes were isolated in the hydrogenated coal liquid. Structural characteristics of the identified S-PAC are discussed and compared with sample properties. The interaction of PASH and S-PAC with PdClz in LEC used in this study was also discussed.

Sulfur aromatic compounds as maturity parameters

The main aim of this study was to evaluate how the distribution of sulfur compounds could be applied in correlation studies and as maturity parameters. The work was concentrated on sulfur containing aromatic compounds, using gas chromatography with dual FID/FPD for the detection of aromatic hydrocarbons and sulfur aromatic compounds. Eleven crude oils from North Sea reservoirs were analysed in addition to sediment samples from nine wells in the same area. Five of the wells were chosen in order to be able to follow the maturity related changes for relatively pure type II kerogens, all Upper Jurassic sediments. Apart from some problems that were probably due to contamination from migrated condensate range hydrocarbons, this sample set gave some relatively clear conclusions as to the maturity related changes. The other four weels contained more varied kerogen types, and the conclusions based on these results were less clear. The oil samples could be separated into two groups based on some of the sulfur aromatic ratios, these two groups being the same as previously determined from other parameters such as biomarkers. The variations in the relative distribution of dibenzothiophene (DBT) and methyldibenzothiophenes (MDBT) were seen to be applicable as maturity indicators. Some results obtained on the effect of changes in organic matter type and reported.

Di- and triaromatic hydrocarbons in fish liver from the North Sea: Multivariate and statistical analysis

Multivariate classification and comparison using principal component analysis and cluster analysis together with statistical analysis using onefactor ANOVA has been made on the alkylhomologue distribution (AHD) of naphthalene, dibenzothiophene and phenanthrene/anthracene (NPD) patterns in 32 fish liver samples. Nineteen samples have been taken from fish caught close to three oil drilling platforms (< 250 m) and 13 from fish caught at reference stations (> 10 000 m). Principal Component Analysis (PCA) of the a priori defined types of samples and on subsets of the total dataset show that there is a systematic difference in the pattern of naphthalenes in fish liver samples caught close to oil platforms and those caught at reference stations. Statistical analysis using ANOVA on each individual variable supports the multivariate interpretation. It is not possible to distinguish between the sets of platform samples from the different surveys. This suggests that the pattern of NPDs in fish liver does not depend on what type of drillmud is discharged from the platform and that there are only small differences in the analytical procedures between surveys. The results show that the livers of migratory fish caught close to oil platforms contain increased amounts of naphthalenes whereas the three-ring aromatic and the sulphur aromatic compounds are not accumulated significantly in the liver.

Biological oxidation of thianthrene, thioxanthene and dibenzothiophene by the thermophilic organismSulfolobus acidocaldarius

Microbial oxidation of some model aromatic organic sulfur compounds such as thianthrene, thioxanthene and dibenzothiophene by the thermophilic organismSulfolobus acidocaldarius has been studied. Sulfate ions released as an oxidation product were measured to quantify the oxidations. The oxidation of the aforementioned refractory aromatic sulfur compounds byS. acidocaldarius may have applications in organic sulfur removal from hydrocarbon fuels such as coal and oil.

The distribution of dibenzothiophenes in Gulf of Mexico sediments

Sediment extracts from 81 piston cores taken in water depths between 70 and 1200 m on the Gulf of Mexico continental shelf and slope were analyzed for dibenzothiophenes by capillary gas chromatography with flame photometric detection (FPD). The major aromatic sulfur compounds detected were dibenzothiophene; methyl, ethyl and propyl dibenzothiophenes; two unidentified sulfur compounds; and a series of benzothiophenes. In general, benzothiophenes (BTs) were detected at only trace levels though this may be due to loss during the analysis. Dibenzothiophenes (DBTs) concentrations ranged from <1 to 1725 ng/g, with an average of 139 ng/g. Vertical distributions generally showed significant increases in DBTs concentrations with depth. DBTs distributions in sediment extracts were similar to oils produced in the northern Gulf of Mexico. Variations from this composition may be due to microbial degradation in the near subsurface. The vertical and molecular distribution of DBTs suggests that the source of DBTs in the Gulf of Mexico sediments studied is upward migrating petroleum. Two unidentified compounds are speculated to be derivatives of DBTs, caused by indigenous microbial activity. This study suggests that DBTs may be useful for detecting seepage from deeper, more mature, source rocks and/or reservoired petroleum.

ChemInform Abstract: Organic Chemistry of Subvalent Transition Metal Complexes. Part 12. Hydrodesulfurization of Organosulfur Heterocycles by Metal Hydride‐Nickel(0) Complexes: Accelerated Single‐Electron Transfer in Carbon‐Sulfur Bond Cleavage.

AbstractThe novel Ni complex (II) which results from the interaction of the complex (I) with LiAlH4 in a THF solution is a powerful desulfurizing agent in homogeneous solution for aromatic sulfur compounds such as (III) or (V).

Improved determination of n-alkanes by forming of urea inclusion compounds.

This report describes the trace analytical method of n-alkanes, based on the inclusion ability of urea, from a mixture of iso-alkanes, cycloalkanes, poly aromatic hydrocarbons and organic sulfur compounds. n-Alkane-urea inclusion complexes were formed by adding ethanol 2 ml of saturated with urea to 0.5 ml of a mixed solution of acetone and n-hexane (3 : 2) containing the above described compounds. The inclusion compounds formed in the hydrophobic medium were precipitated by adding ice-cold ethyl ether and then cooling for 5-10 min in an ice-bath. The precipitates were separated with centrifuge (3000 rpm, 6 min) at 5°C from organic reaction medium. The precipitates were dissolved in 30 ml of 4% Na2SO4 and extracted with n-hexane (total volume, 20 ml), and also the supernatant by the addition of 30 ml of 4% Na2SO4 was treated with n-hexane (20 ml). n-Alkanes were measured in the former n-hexane solution while iso-alkanes and/or others in the latter by each gas chromato-graphic analysis. The recoveries of n-alkanes of C12 and C14 were 67% and 80%, respectively, being recoverd in the past reports with yield of under 40%. The yields of n-alkanes of C15-C28, 2, 2, 4, 4, 6, 8, 8-heptamethylnonane, heptylbenzene, pristane, dibenzothiophene and 3, 4-benzpyrene were 91% on the average, 77%, 79%, 80%, 83% and 84%, respectively. This analytical method was applied to the solvent extracts of a bait of cultured fish and the sea bottom sediment.

The relation between polycyclic aromatic compounds in diesel fuels and exhaust particulates

The polynuclear aromatic compound fractions (PAC) separated by column chromatography from five diesel fuels, a gas oil and sample of kerosene were analysed by capillary column gas chromatography with simultaneous parallel triple detection. The principal polynuclear aromatic hydrocarbons of the fuels are naphthalene, fluorene and phenanthrene and their alkyl derivatives; mutagenic compounds are present in significant concentrations. The principal polynuclear aromatic nitrogen and sulphur compounds of diesel fuel are carbazole and dibenzothiophene and their alkyl derivatives. The PAC of diesel exhaust particulates are similar to those of the fuel, and follow the overall trend of particulate emission with engine load. The 2 to 4-ring PAC in the exhaust are primarily unburnt fuel components. Between 0.2 and 1.0 wt% of these fuel PAC survive the combustion process and comprise a significant concentration of mutagenic compounds in the particulate.

Reactivity of organic sulfur compounds toward solvated electrons: Electron capture by sulfur compounds

Rate constants of a series of organic sulfides and disulfides with solvated electrons in methanol have been determined. The rate constants of alkyl sulfides were of the order of 10 7 mol -1 dm 3s -1. The values for aromatic sulfides were one or two orders of magnitude larger than those for ethylbenzene, diphenylalkanes and aromatic ethers, which resemble the aromatic sulfur compounds in structure, and for the alkyl sulfides. For disulfides, they were very large (10 9-10 10mol -1dm 3s -1). For sulfides except for diphenyl sulfide (first group), a linear relationship was found between log k act and δ E, where k act is the rate constant for reaction after an encounter between a solvated electron and a substrate, and δ E the sum of heat of reaction for electron-capture in gas phase and heat of solvation for thiolate anions, respectively. However, disulfides and diphenyl sulfide (second group) deviated from the linear relationship. The factors controlling the electron-capture rates for these two groups have been examined.

Changes in composition of atmospheric resid upon hydrodesulpurization

This article examines an atmospheric resid from Romashkino crude before and after hydrodesulfurization in order to show how high-resolution mass spectrometry (HRMS) can be applied to high-molecular-weight organic sulfur compounds and aromatic compounds. The original atmospheric resid and a hydrodesulfurized boiler fuel were subjected to adsorptive separation into fractions. Results are presented from an investigation of the fractions that are the most complex in composition, the ''heavy aromatic'' concentrates, the yields of which before and after hydrodesulfurization were 35% and 25.8% by weight on the original atmospheric resid. The data indicate that in the process of hydrodesulfurization, the hydrogenation of aromatic rings is followed by the splitting of the naphthenic rings. The homologue composition was determined along with the group composition. The distribution curves were investigated for the alkyl ions C /SUB n/ H/sup +/ /SUB 2n+1/ in the singlet monoisotope mass spectra. The number of alkyl substituents on the ring from the structure of the mass spectrum in the region of pseudomolecular ions is calculated. It is concluded that in the hydrodesulfurization of an atmospheric resid from Romashkino crude, hydroaromatic hydrocarbons and polythiaalkanes are removed, and alkylaromatic hydrocarbons and derivatives of pyrene, chrysene, benzothiophene, and dibenzothiophene are accumulated.

Composition of concentrates of heterocyclic petroleum compounds isolated by complex-formation with titanium tetrachloride

Summary o 1. The group composition of nitrous bases and aromatic sulphur compounds isolated by complex-formation with titanium tetrachloride from Soviet and West Siberian (Fedorov) crude oils was studied. 2. Homologous series of nitrous bases are characterized by practically identical compounds ranging from C n H 2 n −5 N to C n H 2 n −21 N. Pyridine and quinoline derivatives with alkyl substituents and naphthene rings predominate. 3. Thiacycloparaffins with a number of cnaphthene rings in the molecule of 1 to 5 predominate among saturated sulphur compounds. Unsaturated sulphur compounds are represented mainly by homologues of thiophene, benzo- and dibenzothiophene.

Kinetics of adsorption of aromatic hydrocarbons and organic sulfur compounds by zeolite

Kinetics of adsorption of aromatic hydrocarbons and organic sulfur compounds by zeolite

Chemical and biological weathering of oil, from the Amoco Cadiz spillage, within the littoral zone

The spillage of oil from the wreck of the supertanker Amoco Cadiz resulted in massive oiling of the littoral zone along 320 km of shoreline of the Brittany Coast. This study examined the fate of Amoco Cadiz oil which entered the intertidal zone. Biodegradation by indigenous microbial populations was an extremely important process in the weathering of the oil. Alkanes were preferentially degraded but branched alkanes and polynuclear aromatic compounds also were subject to microbial attack. The chemical evolution of the residual ‘hydrocarbon mixture’ within the littoral zone led to a relative enrichment of isoprenoid alkanes, naphtheno-aromatic and napthenic compounds, alkylated phenanthrenes, aromatic organic sulfur compounds e.g. dibenzothiophenes, hopanes and C27−C31 alkanes. These classes of compounds appear to be most resistant to biological and chemical weathering. Continued inputs of relatively unweathered oil, which may be preserved in subsurface anaerobic sediments, and pooling of oil becomes increasingly important with time, producing a patchy distribution of oil, which has been weathered to varying degrees. The presence of hydrocarbons within the littoral zone, as a highly weathered residual oil, appears to be a long lived (multi-year) phenomenon.

Adsorption of aromatic hydrocarbons and organic sulfur compounds by NaX zeolite

Adsorption of aromatic hydrocarbons and organic sulfur compounds by NaX zeolite

Accumulation, fractionation and release of oil by the intertidal clam Macoma balthica

The bivalve mollusc Macoma balthica accumulated hydrocarbons during 180 days of continuous exposure to Prudhoe Bay crude oil in seawater dispersions with nominal concentrations of 0.03, 0.3 and 3.0 mg l-1. The mollusc's ability to concentrate oil from seawater increased with decreasing oil-in-water concentration. Decreases in oil burden began after 30 to 120 days (depending on the oil concentration) and continued for at least 60 days after exposure to oil ceased. Aliphatic and aromatic hydrocarbons were fractionated in markedly different ways by the bivalve. Branched and cyclic aliphatics in the molecular weight-range dodecane through hexadecane were preferentially retained over straightchain and their higher homologs. Larger and more substituted aromatic compounds were selectively concentrated. There appeared to be no selective concentration of aromatic sulphur compounds.