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Alkanes
Kinds of Alkanes Terms modified by Alkanes Selected AbstractsPreferential flow and aging of NAPL in the unsaturated soil zone of a hazardous waste site: implications for contaminant transportJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 1 2003Kai U. Totsche Abstract Flow of non-aqueous phase liquids (NAPL) in the unsaturated zone is thought to be driven by gravity with a dominant vertical flow direction, and lateral spreading to be limited to the gradient of the relative permeabilities. The effect of soil profile build-up, preferential flow, aging, and groundwater level fluctuations is mostly neglected. The objective of our study was to check the effects of such processes on the fate of NAPL in the unsaturated soil zone. At a hazardous waste site, we conducted a field survey of the unsaturated soil zone and monitored the groundwater for a two year period. We conducted spatially resolved and depth dependent soil sampling and analysis and the evaluation of former ram and core drilling protocols. The samples were analyzed for the 16 EPA PAH and alkanes with GC-MS and GC-FID. 13C-NMR spectroscopy was used to assess structural changes of the NAPL phase. Flow of bulk NAPL along macropores and along preferential permeability structures, like sedimentation discontinuities, are the dominant transport pathways which cause large lateral spreading beyond those expected by the relative permeability gradient. Accumulation of NAPL was found at locations with abrupt textural changes and within the zone of capillary rise. Aging of NAPL results in the depletion in soluble and volatile compounds but also in oxidation and polymerization. It increases the chemical diversity and decreases the mobility of the NAPL. Thus, NAPL flow ceases much earlier than expected from the capillary forces. As chemical transformation is restricted to the NAPL water/air interface, a skin-like thin film is formed which encapsulates and preserves the bulk NAPL from further hardening, limiting contaminant mass transfer from the NAPL to the aqueous phase. Präferenzieller Fluss und Alterung nichtwässriger flüssiger Phasen (NAPL) in der ungesättigten Bodenzone eines Altlastenstandortes: Bedeutung für den Stofftransport Bei der Abschätzung der Tiefenverlagerung von nichtwässrigen Phasen (NAPL) in der ungesättigten Bodenzone ging man bisher davon aus, dass der Fluss im Boden eine dominante vertikale Fließkomponente besitzt. Die Bedeutung bevorzugter Fließwege, des Bodenprofils und der Alterung für die Ausbreitung der NAPL wurde bisher nicht untersucht. Ziel unserer Arbeiten war es daher, die Gültigkeit der Vorstellungen zum Transport von NAPL in der ungesättigten Bodenzone zu überprüfen. Hierzu wurde die ungesättigte Bodenzone an einem ehemaligen Teerwerkstandort untersucht und ein zweijähriges Grundwassermonitoring durchgeführt. Es wurde eine tiefendifferenzierte und räumlich aufgelöste Probenahme mit Rammkernsondierungen und Linern durchgeführt, sowie Bohrprotokolle vorhandener Gutachten ausgewertet. In den Proben wurden Alkane mittels GC-FID und PAK mittels GC-MS bestimmt. NAPL wurden 13C-NMR-spektroskopisch untersucht. Der Fluss von NAPL entlang präferenzieller Fließpfade ist der dominante Prozess der Tiefenverlagerung. Dabei kommt es zu einer starken lateralen Ausbreitung von NAPL weit über den Bereich hinaus, der aufgrund der heterogenen Verteilung der relativen Permeabilitäten erwartet werden würde. Innerhalb des Bodenprofils reichern sich NAPL oberhalb der Grenzflächen mit abruptem Texturwechsel und innerhalb der kapillaren Aufstiegszone an. Alterung der NAPL führt zu einer Zunahme der chemischen Diversität und zu einer Abnahme der Mobilität. Die Tiefenverlagerung von NAPL kommt viel früher zum Erliegen als durch Viskosität und Kapillarkräfte zu erwarten wäre. Die strukturchemischen Veränderungen beschränken sich jedoch auf die Grenzfläche NAPL/Wasser bzw. NAPL/Bodenluft: Es bildet sich eine dünne, verhärtete Grenzschicht aus, die die NAPL umhüllt, die weitere Alterung verlangsamt und den Stoffaustausch zwischen NAPL und Bodenwasser bzw. der Bodenluft verringert. [source] Effects of Partial Confinement on the Specificity of Monomolecular Alkane Reactions for Acid Sites in Side Pockets of Mordenite,ANGEWANDTE CHEMIE, Issue 4 2010Rajamani Gounder Die Dehydrierung linearer Alkane (Butan: blau) und das Cracken verzweigter Alkane (Isobutan: grün) , monomolekulare Reaktionen mit höheren Aktivierungsenergien , zeigen eine stärkere Präferenz für Säurezentren in den Achtring(8-MR)-Seitentaschen von Mordenit, wo Reaktanten und Übergangszustände nur teilweise fixiert werden können. Diese nur partielle Fixierung führt zu höheren Entropien und niedrigeren freien Energien für Ionenpaare in späten Übergangszuständen. [source] Degradation of alkanes by bacteriaENVIRONMENTAL MICROBIOLOGY, Issue 10 2009Fernando Rojo Summary Pollution of soil and water environments by crude oil has been, and is still today, an important problem. Crude oil is a complex mixture of thousands of compounds. Among them, alkanes constitute the major fraction. Alkanes are saturated hydrocarbons of different sizes and structures. Although they are chemically very inert, most of them can be efficiently degraded by several microorganisms. This review summarizes current knowledge on how microorganisms degrade alkanes, focusing on the biochemical pathways used and on how the expression of pathway genes is regulated and integrated within cell physiology. [source] The Prestige oil spill.ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2005Abstract In vitro biodegradation of the Prestige heavy fuel oil has been carried out using two microbial consortia obtained by enrichment in different substrates to simulate its environmental fate and potential utility for bioremediation. Different conditions, such as incubation time (i.e., 20 or 40 d), oil weathering, and addition of an oleophilic fertilizer (S200), were evaluated. Weathering slowed down the degradation of the fuel oil, probably because of the loss of lower and more labile components, but the addition of S200 enhanced significantly the extension of the biodegradation. n -Alkanes, alkylcyclohexanes, alkylbenzenes, and the two- to three-ring polycyclic aromatic hydrocarbons (PAHs) were degraded in 20 or 40 d of incubation of the original oil, whereas the biodegradation efficiency decreased for higher PAHs and with the increase of alkylation. Molecular markers were degraded according to the following sequence: Acyclic isoprenoids < diasteranes < C27 -steranes < ,,-steranes < homohopanes < monoaromatic steranes < triaromatic steranes. Isomeric selectivity was observed within the C1 - and C2 -phenanthrenes, dibenzothiophenes, pyrenes, and chrysenes, providing source and weathering indices for the characterization of the heavy oil spill. Acyclic isoprenoids, C27 -steranes, C1 - and C2 -naphthalenes, phenanthrenes, and dibenzothiophenes were degraded completely when S200 was used. The ratios of the C2 - and C3 -alkyl homologues of fluoranthene/pyrene and chrysene/benzo[a]anthracene are proposed as source ratios in moderately degraded oils. The 4-methylpyrene and 3-methylchrysene were refractory enough to serve as conserved internal markers in assessing the degradation of the aromatic fraction in a manner similar to that of hopane, as used for the aliphatic fraction. [source] Arylation of Hydrocarbyl Ligands Formed from n -Alkanes through C,H Bond Activation of Benzene Using a Triruthenium ClusterEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 23 2009Makoto Moriya Abstract Triruthenium complex 2 containing a perpendicularly coordinated 1-pentyne ligand, which is one of the key intermediates of the reaction of triruthenium pentahydrido complex 1 with n -pentane, reacts with benzene to yield ,3 -benzyne,,3 -pentylidyne complex 5 by C,H bond activation. ,-H elimination form the ,3 -penytylidyne ligand occurred upon heating to yield ,3 -pentenylidene complex 6, which was followed by the formation of closo -ruthenacyclopentadiene complex 8 by the connection of the two hydrocarbyl moieties placed on each face of the triruthenium plane with partial metal,metal bond breaking. Treatment of 8 with pressurized hydrogen resulted in exclusive liberation of n -pentylbenzene, which is difficult to synthesize by conventional Friedel,Crafts alkylation. These sequential transformations correspond to the formation of linear alkylbenzene by the reaction of pentane with benzene on a trimetallic plane. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] The potential for abiotic organic synthesis and biosynthesis at seafloor hydrothermal systemsGEOFLUIDS (ELECTRONIC), Issue 1-2 2010E. SHOCK Geofluids (2010) 10, 161,192 Abstract Calculations are presented of the extent to which chemical disequilibria are generated when submarine hydrothermal fluids mix with sea water. These calculations involve quantifying the chemical affinity for individual reactions by comparing equilibrium compositions with the compositions of mixtures in which oxidation,reduction reactions are inhibited. The oxidation,reduction reactions that depart from equilibrium in these systems provide energy for chemotrophic microbial metabolism. Methanogenesis is an example of this phenomenon, in which the combination of carbon dioxide, hydrogen and methane induced by fluid mixing is far from equilibrium, which can be approached if more methane is generated. Similarly, the production of other organic compounds is also favorable under the same conditions that permit methanogenesis. Alkanes, alkenes, alcohols, aldehydes, carboxylic acids and amino acids are among the compounds that, if formed, would lower the energetic state of the chemical composition generated in mixed fluids. The resulting positive values of chemical affinity correspond to the thermodynamic drive required for abiotic organic synthesis. It is also possible that energy release accompanies biosynthesis by chemotrophic organisms. In this way, hydrothermal ecosystems differ radically from familiar ecosystems at Earth's surface. If captured, the energy released may be sufficient to drive biosynthesis of carbohydrates, purines, pyrimidines and other compounds which require energy inputs. [source] Novel Scorpionate and Pyrazole Dioxovanadium Complexes, Catalysts for Carboxylation and Peroxidative Oxidation of AlkanesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 1 2010Telma F. Abstract The dioxovanadium(V) complexes [VO2(3,5-Me2Hpz)3][BF4] (1) (pz=pyrazolyl), [VO2{SO3C(pz)3}] (2), [VO2{HB(3,5-Me2pz)3}] (3) and [VO2{HC(pz)3}][BF4] (4), bearing pyrazole or scorpionate ligands, were obtained by reaction of triethyl vanadate [VO(OEt)3] with hydrotris(3,5-dimethyl-1-pyrazolyl)methane [HC(3,5-Me2pz)3] or 3,5-dimethylpyrazole (3,5-Me2Hpz; 1), lithium tris(1-pyrazolyl)methanesulfonate {Li[SO3C(pz)3], 2}, potassium hydrotris(3,5-dimethyl-1-pyrazolyl)borate {K[HB(3,5-Me2pz)3], 3} and hydrotris(1-pyrazolyl)methane [HC(pz)3, 4], respectively. Treatment of [VO(OEt)3] with potassium hydrotris(1-pyrazolyl)borate {K[HB(pz)3]} led to the mixed ,3 -tris(pyrazolyl)borate and ,2 -bis(pyrazolyl)borate oxovanadium(IV) complex [VO{HB(pz)3}{H2B(pz)2}, 5]. The compounds were characterized by elemental analyses, IR, NMR and EPR spectroscopy, FAB and ESI mass spectrometry, cyclic voltammetry and, for 5, also by single crystal X-ray diffraction analysis. All complexes exhibit catalytic activity in the single-pot carboxylation [in trifluoroacetic acid/potassium peroxodisulfate (CF3COOH/K2S2O8)] of gaseous alkanes (methane and ethane) to carboxylic acids (yields up to 40%, TONs up to 157) and in the peroxidative oxidation [in water/acetonitrile (H2O/NCMe)] of liquid alkanes (cyclohexane and cyclopentane) to the corresponding alcohols and ketones (yields up to 24%, TONs up to 117), under mild conditions. [source] Highly Active and Recyclable Heterogeneous Iridium Pincer Catalysts for Transfer Dehydrogenation of AlkanesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 1-2 2009Zheng Huang Abstract Pincer-ligated iridium complexes have proven to be highly effective catalysts for the dehydrogenation and transfer-dehydrogenation of alkanes. Immobilization onto a solid support offers significant potential advantages in the application of such catalysts particularly with respect to catalyst separation and recycling. We describe three approaches toward such immobilization: (i) covalent attachment to a Merrifield resin, (ii) covalent bonding to silica via a pendant alkoxysilane group, and (iii) adsorption on ,-alumina (,-Al2O3), through basic functional groups on the para- position of the pincer ligand. The simplest of these approaches, adsorption on ,-Al2O3, is also found to be the most effective, yielding catalysts that are robust, recyclable, and comparable to or even more active than the corresponding species in solution. Spectroscopic evidence (NMR, IR) and studies of catalytic activity support the hypothesis that binding occurs at the para- substituent and that this has only a relatively subtle and indirect influence on catalytic behavior. [source] Liquid Chromatographic Separation of Olefin Oligomers and its Relation to Separation of Polyolefins , an OverviewMACROMOLECULAR SYMPOSIA, Issue 1 2009Tibor Macko Abstract Summary: Linear and branched alkanes are oligomers of polyethylene. Alkanes with higher molar masses are called waxes. These substances are widely used as fuels, oils, lubricants, etc. and for these reasons many groups have tried to analyse, separate and characterise alkanes by various methods, including liquid chromatography. Alkanes may be separated according to their size in solution by SEC. In addition to chromatographic systems separating in the SEC mode, various sorbent-solvent systems have been published, where alkanes have been separated one from another by adsorption and/or precipitation mechanism. The mobile phase is either a non-polar solvent or a polar solvent or a mixture of a solvent and a non-solvent for alkanes. Even near critical conditions, which have several advantages for applications of HPLC in polymer analysis, have been identified for alkanes. Moreover, selective separations of branched alkanes according to their structure have been published. In the majority of these published studies, solvents with low boiling points have been used as the mobile phases, which do not allow dissolution of crystalline polyolefins at atmospheric pressure. However, taking into account experiences with the separation of alkanes, new HPLC systems for the separation of polyolefins may be developed. This is a major challenge and first results are presented in this contribution. [source] Estimation of Aqueous-Phase Reaction Rate Constants of Hydroxyl Radical with Phenols, Alkanes and AlcoholsMOLECULAR INFORMATICS, Issue 11-12 2009Ya-nan Wang Abstract A quantitative structure activity relationship (QSAR) model was developed for the aqueous-phase hydroxyl radical reaction rate constants (kOH) employing quantum chemical descriptors and multiple linear regressions (MLR). The QSAR development followed the OECD guidelines, with special attention to validation, applicability domain (AD) and mechanistic interpretation. The established model yielded satisfactory performance: the correlation coefficient square (R2) was 0.905, the root mean squared error (RMSE) was 0.139, the leave-many-out cross-validated QLMO2 was 0.806, and the external validated QEXT2 was 0.922 log units. The AD of the model covering compounds of phenols, alkanes and alcohols, was analyzed by Williams plot. The main molecular structural factors governing kOH are the energy of the highest occupied molecular orbital (EHOMO), average net atomic charges on hydrogen atoms (), molecular surface area (MSA) and dipole moment (,). It was concluded that kOH increased with increasing EHOMO and MSA, while decreased with increasing and ,. [source] Hydrodeoxygenation of Lignin-Derived Phenols into Alkanes by Using Nanoparticle Catalysts Combined with Brønsted Acidic Ionic Liquids,ANGEWANDTE CHEMIE, Issue 32 2010Ning Yan Dr. Wertschöpfung im Tandem: Ein katalytisches System bestehend aus Metall-Nanopartikeln (NPs) und einer funktionalisierten Brønsted-sauren ionischen Flüssigkeit (IL) in einer nichtfunktionalisierten IL wird beschrieben (siehe Bild). Das System ist hoch effizient für die Umsetzung von Lignin abgeleiteter phenolischer Verbindungen zu Alkanen, wobei die Hydrierung und Dehydratisierung als Tandemprozess ablaufen. [source] Experimental Confirmation of the Low-Temperature Oxidation Scheme of Alkanes,ANGEWANDTE CHEMIE, Issue 18 2010Frédérique Battin-Leclerc Dr. Vermutung bestätigt: Die Entwicklung von Verbrennungsmotoren beruht auf dem Wissen um den Mechanismus der Selbstzündung von Kohlenwasserstoffen. Eine grundsätzliche Annahme konnte nun experimentell bestätigt werden: Die Bildung von Ketohydroperoxiden wurde unter Bedingungen beobachtet, die denjenigen vor der Selbstzündung nahekommen. [source] ChemInform Abstract: Bis(enaminones): Key Intermediates for Novel ,,,-Bis(pyrazolylphenoxy), Bis(pyranylphenoxy), and Bis(benzo[b]furanylphenoxy) Alkanes.CHEMINFORM, Issue 37 2009Ashraf A. Abbas Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Synthesis of Functionalized Diaryl Alkanes from Azines.CHEMINFORM, Issue 24 2009Rudolf M. Manih Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Coupling of Nitrogen Heteroaromatics and Alkanes Without Transition Metals: A New Oxidative Cross-Coupling at C,H/C,H Bonds.CHEMINFORM, Issue 20 2009Guojun Deng Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Iron Catalyst for Oxidation in Water: Surfactant-Type Iron Complex-Catalyzed Mild and Efficient Oxidation of Aryl Alkanes Using Aqueous TBHP as Oxidant in Water.CHEMINFORM, Issue 10 2009Takashi Nagano Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Decarboxylative Allylation Using Sulfones as Surrogates of Alkanes.CHEMINFORM, Issue 10 2009Jimmie D. Weaver Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Palladium-Catalyzed Intramolecular Coupling of Arenes and Unactivated Alkanes in Air.CHEMINFORM, Issue 5 2009Benoit Liegault Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Regio- and Diastereoselective Decarboxylative Coupling of Heteroaromatic Alkanes.CHEMINFORM, Issue 34 2007Shelli R. Waetzig Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] A Novel Reduction Reaction for the Conversion of Aldehydes, Ketones and Primary, Secondary and Tertiary Alcohols into Their Corresponding Alkanes.CHEMINFORM, Issue 46 2006Rama D. Nimmagadda Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] A Mild Radical Procedure for the Reduction of B-Alkylcatecholboranes to Alkanes.CHEMINFORM, Issue 9 2006Davide Pozzi Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] NaIO4 -Mediated C,H Activation of Alkylbenzenes and Alkanes with LiBr.CHEMINFORM, Issue 48 2005Tanveer M. Shaikh Abstract For Abstract see ChemInform Abstract in Full Text. [source] Reaction of CBrF2,CBrF2 with Hydrazones of Aromatic Aldehydes Novel Efficient Synthesis of Fluorocontaining Alkanes, Alkenes and Alkynes.CHEMINFORM, Issue 52 2004Valentine G. Nenajdenko Abstract For Abstract see ChemInform Abstract in Full Text. [source] Novel Indium-Mediated Ternary Reactions Between Indole-3-carboxaldehydes,Allyl Bromide,Enamines: Facile Synthesis of Bisindolyl- and Indolyl-Heterocyclic Alkanes.CHEMINFORM, Issue 22 2003Subodh Kumar Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: Catalytic Oxyalkylation of Alkenes with Alkanes and Molecular Oxygen via a Radical Process Using N-Hydroxyphthalimide.CHEMINFORM, Issue 6 2002Takafumi Hara Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Amavadine as a Catalyst for the Peroxidative Halogenation, Hydroxylation and Oxygenation of Alkanes and Benzene.CHEMINFORM, Issue 1 2001Patricia M. Reis Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Significant Influence of Zn on Activation of the C-H Bonds of Small Alkanes by Brønsted Acid Sites of Zeolite,CHEMPHYSCHEM, Issue 17 2008Alexander G. Stepanov Prof. Abstract Herein, we analyze earlier obtained and new data about peculiarities of the H/D hydrogen exchange of small C1,n -C4 alkanes on Zn-modified high-silica zeolites ZSM-5 and BEA in comparison with the exchange for corresponding purely acidic forms of these zeolites. This allows us to identify an evident promoting effect of Zn on the activation of CH bonds of alkanes by zeolite Brønsted sites. The effect of Zn is demonstrated by observing the regioselectivity of the H/D exchange for propane and n- butane as well as by the increase in the rate and a decrease in the apparent activation energy of the exchange for all C1,n -C4 alkanes upon modification of zeolites with Zn. The influence of Zn on alkane activation has been rationalized by dissociative adsorption of alkanes on Zn oxide species inside zeolite pores, which precedes the interaction of alkane with Brønsted acid sites. [source] FT-IR measurements of petroleum fluid inclusions: methane, n -alkanes and carbon dioxide quantitative analysisGEOFLUIDS (ELECTRONIC), Issue 1 2001J. Pironon Abstract A recent advancement in petroleum geochemistry is to model fossil oil composition using microthermometric and volumetric data acquired from individual fluid inclusion analysis. Fourier transform infrared (FT-IR) microspectroscopy can record compositional information related to gas (CH4 and CO2) and alkane contents of petroleum inclusions. In this study, a quantitative procedure for FT-IR microspectrometry has been developed to obtain, from individual fluid inclusions, mol percentage concentrations of methane, alkanes and carbon dioxide as constraints to thermodynamic modelling. A petroleum inclusion in a sample from the Québec City Promontory nappe area was used as standard to record a reference spectrum of methane. The analytical procedure is based on the measurement of CH4/alkane and CH4/CO2 band area ratios. CH4/alkane infrared band area ratio is obtained after spectral subtraction of the reference methane spectrum. This area ratio, affected by absolute absorption intensities of methane, methyl and methylene, provides a molar CH4/alkane ratio. Methyl/methylene ratio (CH2/CH3) ratio is obtained following procedures established in previous work. CO2/CH4 concentration ratio is estimated from relative absolute absorption intensities. Application to natural inclusions from different environments shows good correlation between FT-IR quantification and PIT (petroleum inclusion thermodynamic) modelling. [source] A strain isolated from gas oil-contaminated soil displays chemotaxis towards gas oil and hexadecaneENVIRONMENTAL MICROBIOLOGY, Issue 10 2003Mariana P. Lanfranconi Summary In this report we describe the isolation of a strain from soil contaminated with gas oil by taking bacteria from a chemotactic ring on gas oil-containing soft agar plates. Partial 16 S rDNA sequencing of the isolated strain showed 99.1% identity with Flavimonas oryzihabitans. It was not only able to degrade different aliphatic hydrocarbons but it was also chemotactic towards gas oil and hexadecane, as demonstrated by the use of three different chemotaxis methods, such as agarose plug and capillary assays and swarm plate analysis. In addition, the strain was chemotactic to a variety of carbon sources that serve as growth substrates, including glucose, arabinose, mannitol, glycerol, gluconate, acetate, succinate, citrate, malate, lactate and casaminoacids. This is the first report on chemotaxis of a hydrocarbon-degrading bacterium towards a pure alkane, such as hexadecane. The fact that environmental isolates show chemotaxis towards contaminant/s present in the site of isolation suggests that chemotaxis might enhance biodegradation by favouring contact between the degrading microorganism and its substrate. [source] Facile Synthesis of Flexible Bis(pyrazol-1-yl)alkane and Related Ligands in a Superbasic MediumEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 30 2007Andrei S. Potapov Abstract Flexible ligands 1,3-bis(pyrazol-1-yl)propanes, bis[2-(pyrazol-1-yl)ethyl] ethers, and bis[2-(3,5-dimethylpyrazol-1-yl)ethyl]amine were prepared by a facile procedure involving the reaction of pyrazoles with 1,3-dibromopropane, bis(2-chloroethyl) ether or bis(2-chloroethyl)amine hydrochloride in a superbasic medium (dimethyl sulfoxide/potassium hydroxide). Reaction of bis(2-chloroethyl)amine and pyrazole unexpectedly led to 1,4-bis[2-(pyrazol-1-yl)ethyl]piperazine. The corresponding 4,4,-diiodo-substituted bis(pyrazole) derivatives were prepared by oxidative iodination with I2/HIO3/H2SO4 in acetic acid. Vilsmeier,Haak formylation of some of the prepared compounds yielded the corresponding dialdehydes.(© Wiley-VCH Verlag GmbH & Co. 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