Gas-liquid chromatographic analysis of C10-C16n-paraffins,isoparaffins and α-olefins in a low-temperature coal tar

21 C₁₀-C₁₆ hydrocarbons, 7 each of n-paraffins, 2-methyl alkanes and α-olefins, were identified in a low-temparature bituminous coal tar by means of gas-liquid chromatography. Quantitative determinations were made on all of these constituents. It was found that the curves for the plots of logarithms of relative retention against normal boiling points for C₁₀-C₁₆n-paraffins and α-ole fins are parallel. A similar parallel curve for the 2-mathyl alkane series was derivred, using the Known point for 2-methyl decane. This correlation curve was used for the identification of several 2-methyl alkalnes. Naphthenes and trans-olefins were found in small amounts.     

Distribution of weight,density, and molecular weight in crude oil derived from computerized capillary GC analysis

Chromatographic separation of crude oil components has been performed on a 50 m Chrompack Sil 5 fused silica capillary column, temperature programmed from 10 to 300°C. Approximately 70 peaks eluting before n-nonane (n-C₉) and all normal paraffins to n-C₁₉ were identified by a retention time table. Peak areas were converted to weight % using 1-heptene as internal standard and relative response factors. Components were divided into boiling range groups from n-C₆ to n-C₁₉. Paraffinic, naphthenic, and aromatic distributions were obtained for the boiling point fractions up to n-C₉. Group average densities and molecular weights were calculated from pure component properties up to n-C₉. Knowing the density and molecular weight as functions of boiling range group to n-C₉, these functions can be extrapolated to n-C₁₉, based on data and correlations from more than 20 distillations of paraffinic North Sea oils adn condensates. The densities and molecular weights of the C₁₀+ and the C₂₀+ residues were calculated to satisfy a balance of weight, volume, and number of moles for the whole sample. Measurements on the residues were used to cross-evaluate the GC method against distillation. The difference in weight was estimated to be less than ± 0.5% in absolute terms for the C₁₀+ residue. The corresponding figure for C₂₀+ was ± 2%. Relatively, calculated densities are within ± 1%, molecular weights within ± 2% compared to direct measurements. Calculations were performed by a BASIC program in a GC interfaced computer.     

Synthesis of <Emphasis Type="Italic">N</Emphasis>-alkylacrylamides from commercial fractions of higher olefins by the Ritter reaction

The influence of temperature, reactant ratio, and catalyst (sulfuric acid) concentration on the product composition in synthesis of higher N-acrylamides from acrylonitrile and commercial fractions of α-olefins C₈, C₁₀, C₁₂-C₁₄, C₁₆-C₁₈, and of propylene trimers and tetramers by the Ritter reaction was examined.     

Diffusion of linear paraffins in silicalite studied by the ZLC method in the presence of CO2

The diffusion behavior of C₄–C₁₀ n-alkanes in silicalite-1 has been investigated by using the Zero Length Column method. The diffusivities derived from measurements at different purge rates with different purge gases confirming intracrystalline diffusion control. Data are compared with results reported in the literature for MFI zeolites. The diffusivities were found to be consistent and agree well with data previous obtained by ZLC. However, these data showed a remarkable disagreement with other reported techniques (PFG-NMR, QENS and Permeation). The eventual influence of carbon dioxide (CO₂) adsorption on diffusion properties of n-alkanes in silicalite was also investigated. For this purpose, a series of experiments was performed involving hydrocarbons mixed with CO₂. Data were obtained at 303 K and flow rates between 20 and 80 mL/min. The presence of CO₂ does not seem to influence the intracrystalline transport rate of the investigated light hydrocarbons (n-C₄ and n-C₆). On the other hand, the situation for n-C₈ and n-C₁₀ is more complex. The diffusivity values are higher compared to the previously reported values.     

Phytochemical Study on Moghania Strobilifera

n-C₂₆H₅₄, n-C₂₇H₅₆, n-C₂₈H₅₈, n-C₂₉H₆₀, n-C₃₀H₆₂, n-C₃₁H₆₄, n-C₃₂H₆₆, n-C₃₃H₆₈, stigmasterol, β-sitosterol and two unidentified compounds: a saturated ester (mp 79-81°C); an unsaturated alcohol (mp 87-88°C) were isolated from the whole herb of Moghania strotilifera.     

Measurement of non-methane hydrocarbons in Taipei city and their impact on ozone formation in relation to air quality

Air pollutants data from semi-continuous measurements at multiple sampling sites in Taipei metropolitan area of Taiwan was obtained by collecting air samples in canisters. The hydrocarbon composition was determined by using GC/MS and GC/FID. The air samples were pre-concentrated onto glass beads prior to separation by PLOT and DB-1 columns of GC. The method showed detection limit of <1 ppb and relative standard deviation in the range of 5-30% for different compounds. Aromatic hydrocarbons (toluene, benzene, etc.) and aliphatic hydrocarbons (ethylene, acetylene, propane, etc.) were correlated primarily to determine the source of emission. The estimated hydrocarbons were ranked according to their abundance and photochemical reactivity. The criteria pollutants, ozone and NO₂ were measured by UV-differential optical absorption spectroscopy (UV-DOAS), and were utilized to determine the relative importance of non-methane hydrocarbons (NMHC) and significant contribution of NO₂ in limiting ozone formation. The obtained results suggest that ozone formation in Taipei city is probably limited by the supply of non-methane hydrocarbons. The concentration profile of targeted pollutants was compared to other metropolitan areas to determine air quality and the pollutant sources.     

Synthesis and Tribological Characteristics of Oligoorganosiloxanes with Higher n-Alkyl Substituents

A procedure was developed for hydrosilylation of -olefins with oligohydrosiloxanes, and a series of comb-shaped organosiloxanes of the general formula R₃SiO(R₂SiO)_m(RR'SiO)_nSiR₃ (where R is CH₃, C₂H₅; R' is n-alkyl C₈-C₁₈) with random distribution of dimethylsiloxane (or diethylsiloxane) and methylalkylsiloxane (or ethylalkylsiloxane) units were obtained. The physicochemical characteristics of these oligomers were studied, with particular attention given to their lubricating properties (diameter of the wear spot and critical jamming load), which were compared to those of lubricating oils based on organosilicon compounds (PMS-100, KhS-2-1) and hydrocarbon-based MS-20 oil.     

Application of urea adduction technique to polluted urban aerosols for the determination of hydrogen isotopic composition of n-alkanes

We examined an applicability of an improved urea adduction technique for the determination of hydrogen isotopic composition (δD) of homologous series of n-alkanes present in polluted urban aerosols using GC/TC/IRMS. Unresolved complex mixture (UCM) of hydrocarbons that interferes with accurate isotope measurements of n-alkanes was removed from n-alkane fraction by a urea adduction method. Recoveries of C₂₀ to C₃₀ n-alkanes during the urea adduction procedure were greater than 90% when the concentrations of total n-alkanes exceed 6.1?µg?mL^?1. Our compound-specific D/H ratios confirm the absence of significant hydrogen isotope fractionation in n-alkanes during urea adduction and recovery of the purified n-alkane fraction. We applied this technique to the urban aerosols that contain a large quantity of UCM to measure δD of C₂₀ to C₃₅ n-alkanes in urban aerosols from Tokyo and Sapporo with an accuracy less than 10‰. We found that the δD values widely ranged from ?38 to ?179‰. Based on the δD values of individual n-alkanes in aerosol samples, we can obtain further information on the sources of aerosol n-alkanes and their source regions, and the atmospheric processes such as long-range transport and atmospheric mixing of air masses of different origin.     

Synthesis of mixtures of aromatic and aliphatic hydrocarbons from CO and H2 over Fe catalysts

It was determined that 8.2% Fe-1–4.5% K/Al ₂ O ₃ catalysts are active in the synthesis of C ₁ -C ₆ aliphatic and C ₆ -C ₈ aromatic hydrocarbons (AH) from mixtures of CO:H ₂ =1:2–2:1. The AH content in the liquid reaction products is 90%. A discussion of the synthesis schemes for AH is presented.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, Moscow 117334. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 3, pp. 546–551, March, 1992.     

Soluble magnesium–titanium catalysts for ethylene polymerization. I

A study has been made of a catalyst system comprising the heptane-soluble magnesium and titanium compounds in combination with an organoaluminum compound for ethylene polymerization at a high temperature. The productivity for ethylene polymerization of the catalyst system, n-butylethyl magnesium (BEM)-2-ethyl hexanol (C₈H₁₇OH)-tetra-n-butoxytitanium[Ti(OBu)₄]/diethyl aluminum chloride (DEAC) is higher than for MgCl₂-Cl₂-C₈H₁₇ OHTi(OBu)₄/DEAC and much higher than MgCl₂-Ti(OBu)₄/DEAC. The nature of the three different catalyst systems have been discussed in comparison with experimental data on polymerization behavior and the data of the elemental and x-ray diffraction analysis of the solid products obtained from the reactions between the catalyst components.     

Thermodynamic interactions in rubbery polymer/gas systems

The Flory–Huggins interaction parameters χ for 23 gases (He, Ne, Ar, Kr, Xe, H₂, N₂, O₂, N₂O, CO₂, CH₄, C₂H₄, C₂H₆, C₃H₆, C₃H₈, 1,3-C₄H₆, four C₄H₈'s, n-C₄H₁₀, iso-C₄H₁₀, and n-C₅H₁₂) in five rubbery polymers (1,2-polybutadiene (PB), poly(ethylene-co-vinyl acetate)) (EVAc), polyethylene (PE), polypropylene (PP), and poly(dimethyl siloxane) (PDMS) were determined from either literature data on Henry's law coefficient and partial molar volume or those on sorptive dilation for each polymer/gas system. Values of χ for the gases increased in the order of PDMS < PP ≡ PB < EVAc ≡ PE. Among the gases except He and H₂ whose χ values are not reliable, Ne and Xe have respectively the highest and the lowest values of χ for the polyolefins. The χ values of the hydrocarbons were compared together with previously reported χ values of n-alkanes C₃-C₁₀. The dependencies of χ upon concentration and temperature were discussed on the basis of the literature data. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35 : 1049–1053, 1997     

Utilization of α-olefins obtained by pyrolysis of waste high density polyethylene to synthesize α-olefin-succinic-anhydride based cold flow improvers

A new route of utilization of α-olefin rich hydrocarbon fractions obtained by waste polymer pyrolysis was investigated. α-olefin-succinic-anhydride intermediate-based pour point depressant additives for diesel fuel were synthesized, in which reactions needed α-olefins were obtained by pyrolysis of waste high-density polyethylene (HDPE). Fraction of α-olefins was produced by the de-polymerization of plastic waste in a tube reactor at 500℃ in the absence of catalysts and air. C_17~22 range of mixtures of olefins and paraffins were separated for synthesis and then, these hydrocarbons were reacted with maleic-anhydride (MA) for formation of α-olefin-succinic-anhydride intermediates. The olefin-rich hydrocarbon fraction contained approximately 60% of olefins, including 90%~95% α-olefins. Other intermediates were produced in the same way by using commercial C₂₀ α-olefin instead of C_17~22 olefin mixture. The two different experimental intermediates with number average molecular weights of 1850g/mol and 1760g/mol were reacted with different alcohols: 1-butanol, 1-hexanol, 1-octanol, i-butanol, and c-hexanol to produce their ester derivatives. The synthesized ten experimental pour point depressants were added in different concentrations to conventional diesel fuel, which had no other additive content before. The structure and efficiency of experimental additives were followed by different standardized and non-standardized methods. Results showed that the experimental additives on the basis of the product of waste pyrolysis were able to decrease not only the pour but also the cloud point and cold filter plugging point (CFPP) of diesel fuel, whose effects could be observed even if the concentration of additives was low. Furthermore, all additives had anti-wear and anti-friction effects in diesel fuel.     

Nonglyceride lipids of the seed coats ofArtemisia absinthium andOnopordum acanthium

The seed coats ofArtemisia absinthium andOnoporum acanthium have been shown to contain paraffinic hydrocarbons (C₃₁-C₂₅ and C₃₁-C₂₇, respectively), wax esters (C₃₂-C₂₃ and C₅₁-C₃₃), acetyltriterpenols (six types, five types), and acyltriterpenols with a predominance of palmitoyltriterpenols (esters of higher saturated unbranched C_32:0-C_12:0 fatty acids and triterpenols with a molecular weight of 426 belonging to the ursene group).Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 154–157, March–April, 1981.     

Analysis of light hydrocarbons (C2?C6) at PPT levels by high resolution gas chromatography

An analytical technique is described which allows the determination of C₂? C₆ hydrocarbons in the ppt-range from up to 21 air samples after removal of air humidity. Preconcentration is carried out on a two stage cryotrap system. The compounds are separ ated on a temperature-programmed capillary coated with Al₂ O₃. Detection limits (S/N 2:1) of 1.5 to 5 ppt were obtained for air samples from the Arctic. The reproducibility of the method was about 3% at the 50–100 ppt level. Practical problems are discussed in detail.     

Achieving strictly linear polyethylenes by the NNN-Fe precatalysts finely tuned with different sizes of ortho-cycloalkyl substituents

Six examples of newly synthesized α,α’-bis (aryl)-2,3:5,6-bis (pentame thylene)pyridyliron complexes [2,3:5,6-{C₄H₈C(NAr)}₂C₅HN]FeCl₂ (Ar = 2-(c-C₅H₉)-6-MeC₆H₃ Fe1 , 2-(c-C₆H₁₁)-6-MeC₆H₃ Fe2 , 2-(c-C₈H₁₅)-6-MeC₆H₃ Fe3 , 2-(c-C₅H₉)-4,6-Me₂C₆H₂ Fe4 , 2-(c-C₆H₁₁)-4,6-Me₂C₆H₂ Fe5 , 2-(c-C₈H₁₅)-4,6-Me₂C₆H₂ Fe6 ; c refers as cyclic), on activation with methylalumoxane (MAO) or modified MAO (MMAO), exhibit high activities towards ethylene polymerization, producing strictly linear polyethylenes with terminal vinyl groups. The catalytic performances are systematically investigated along with various polymerization parameters as well as the microstructures of resultant polyethylenes. The steric hindrances of ortho-cycloalkyl substituents of N_imino-aryl groups significantly affect the activities of the corresponding iron precatalysts as well as the microstructures of resultant polyethylenes: higher steric hindrance the ortho-cycloalkyl substituents, higher activity the iron precatalyst, lower molecular weight the resultant polyethylenes. Experimental observations are additionally supported by the computational study. The resultant polyethylenes exhibited excellent hydrophobicity.     

13C n.m.r. studies of organosilanes: II—substituent chemical shift parameters for alkoxysilanes

The ¹³C n.m.r. spectra of forty alkoxysilanes of the general type X_nSi(OR)_4–n (X = CH₃, C₆H₅, H; R = CH₃, C₂H₅, n-C₃H₇, i-C₃H₇, n-C₄H₉, i-C₄H₉, s-C₄H₉, n-C₅H₁₁, CH(CH₃)(C₆H₅), C₆H₅) have been recorded and assigned. The chemical shifts of the α-carbon resonances of the alkoxy groups are shown to depend on both the nature of the alkoxy group and the number and type of substituents on the silicon. Regression analyses of the data give empirical substituent chemical shift (SCS) parameters for the silyl substituents. The β-carbon resonances are shown to be dependent on the presence of the silyl group, but not the specific silyl substituents.     

Synthesis and transformations of metallacycles. 29. Direct alumination of olefins, conjugated dienes, and acetylenes with alkylhaloalanes catalyzed by Zr and Ti complexes

Catalytic methods were developed for the synthesis of acyclic 1,2- and 1,4-dialuminum compounds by the reactions of olefins, dienes, or acetylenes with R₂AlCl (R = Et, Et₂N, (cyclo-C₆H₁₁)₂N, BuⁿO, or n-C₆H₁₃O) in the presence of Ti- or Zr-containing complex catalysts and magnesium metal as an acceptor of chloride ions.     

Excess enthalpies of binary mixtures of 2-, 3-, 4-picoline+n-alkane (C6H14-C10H22) at 298.15 K. Comparison with theory

The molar excess enthalpies measured for binary mixtures of 2-, 3-, 4-picoline +n-alkane (C₆H₁₄-C₁₀H₂₂) at 298.15 K have been compared with the Prigogine-Flory-Patterson theory and the Extended Real Associated Solution model estimations.

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Zusammenfassung Die bei 298.15 K gemessenen molaren Zusatzenthalpien binärer Mischungen aus 2-,3-,4-Picolin und einemn-Alkan (C₆H₁₄-C₁₀H₂₂) wurden mit den nach der Prigonine-Flory-Patterson-Theorie und den nach dem erweiterten Modell real assoziierter Lösungen (ERAS) berechneten Weiten verglichen.

     

New cerebrosides from the marine sponge Oceanapia sp.

New cerebrosides containing N-acetylglucosamine were isolated from the marine sponge Oceanapia sp. Some of them contain n-and iso-C₁₈-and iso-C₁₉-phytosphingosines N-acylated by n-C_16:0, n-C_17:0, and n-C_18:0 fatty acids, some other are derivatives of iso-and anteiso-C₁₇-,-C₁₈-, and-C₁₉-phytosphingosines N-acylated by long-chain (C₂₄-C²⁸) α-hydroxy acids. The structures of these compounds were determined by NMR spectroscopy, MALDI-TOF mass spectrometry, and by chemical transformations. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 895–899, May, 2006.     

Kinetic regularities of the heat release during the reactions of aliphatic hydrocarbons with aqueous HNO3

The kinetics of the heat release during the reactions of aqueous HNO₃ withn-heptane andn-octadecane was studied. The kinetic regularities of the reactions of hydrocarbons C₇H₁₆−C₁₈H₃₈ with HNO₃ and the heats of the reactions were described. At all stages, except initial, the hydrocarbon reacts with NO₂ and nitric acid reproduces NO₂ in the reaction with NO. The accumulation of NO₂ results in the acceleration of the process. When the pressure of the hydrocarbon vapor is equilibrium, its reaction with NO₂ can also proceed in the gas phase. The contribution of this reaction to the total heat release was estimated. The additives of aromatic and unsaturated hydrocarbons to aliphatic hydrocarbons increase strongly the initial rate of the heat release and changes slightly the subsequent stages of the process. Naphthenic hydrocarbons have almost no effect on the kinetic parameters of the process. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 35–40, January, 1998.