Fullerenes from kerogen by laser ablation fourier transform ion cyclotron resonance mass spectrometry

Raw oil shale, kerogen (demineralized shale) and carbonaceous residues from kerogen pyrolysis in the range 350–700°C (at 50°C intervals) were studied by laser ablation Fourier transform ion cyclotron resonance mass spectrometry using the fundamental frequency of Nd: YAG laser (1064 nm). Normally, pyrolysis of the raw materials produces oil and the resulting residues have decreased hydrogen to carbon ratios and exhibit relative increases in aromatic carbons. Raw shale and kerogen give positive-ion spectra with mainly protonated species of m/z 100–400. Laser ablation positive-ion mass spectra of the pyrolysis products of the kerogen show the presence of C₆₀, C₇₀ and other fullerene ions with a distribution of higher mass fullerene ions up to m/z 4000. Using high laser powers (100–3000 MW cm^?2), the residue from pyrolysis at 350°C initially did not produce any fullerene ions (apart from traces of C₆₀ and C₇₀), but after continued ablation a cavity was formed in the target and a wide distribution of fullerene ions was obtained with subsequent laser pulses. Residues obtained from the pyrolysis of kerogen at 400–500°C produced fullerene ions at both low (4–200 kW cm^?2) and high laser powers. The 550°C pyrolysis residue gave only small amounts of C₆₀ and C₇₀ positive ions at low laser power whereas residues from the pyrolysis of kerogen above 550°C did not give fullerene ions over a wide range of laser powers. It is proposed from the above results that the changes in the aromatic nature of the kerogen residues with increasing pyrolysis temperature are directly related to the ease of fullerene formation. This is possibly due to the formation of large polycyclic aromatic systems at pyrolysis temperatures above 400°C, formed in the residues. It should be noted that the shale samples (raw or pyrolysed) did not generate fullerene ions under any of the conditions employed in these experiments.     

Insights into coal structure from degradation with ruthenium tetroxide and tandem mass spectrometry

The products of ruthenium tetroxid oxidation of coal (Illinois No. 2) at ambient temperature were examined by tandem mass spectrometry using positive and negative chemical ionization. The negative-ion mass spectrum of the coal sample displays seven homologous series of ions. Individual compounds were characterized by recording daughter spectra. In this way, the following types of compounds were identified: aliphatic dicarboxylic acids, aromatic dicarboxylic and tricarboxylic acids, anhydrides of the di- and tri-carboxylic acids, and dianhydrides corresponding to the tetracarboxylic aromatic acids. The positive-ion mass and daughter spectra provided additional confirmation. Two series of ions dominate the positive-ion mass spectrum, those from the aliphatic dicarboxylic acids, and the corresponding anhydrides. The fragmentation behavior of model compounds was examined to confirm these assignments. The carboxylic acids and anhydrides identified suggest the presence of particular structural features in the coal prior to oxidation. These include C₂–C₆ aliphatic bridges between aromatic units, fused ring aromatic structures, tetralin and indan structures.     

煤热解过程中含氮气相产物转化规律的实验研究

为了研究煤在热解过程中含氮气相产物的生成规律,在滴管炉反应系统中对四种原煤以及两种脱除矿物质煤样分别在500℃、700℃、900℃和1100℃进行了实验研究。结果表明,随着温度的升高,作为NO前驱物的HCN和NH3的收率随之增加,N2的收率也增加。煤种对含氮气相产物的生成规律也有着较大的影响,煤化程度比较低的煤在热解过程中,燃料氮向气相含氮产物的转化率较高;煤化程度比较高的煤转化率则偏低,大部分的氮缩聚在多环芳香结构中,成为焦炭氮。煤中的矿物质对燃料氮向N2的转化起到了促进作用,而对燃料氮向HCN和NH3的转化起到了抑制作用。     

Chromatographic study of the organic matter from Moroccan Rif bituminous rocks

The bituminous rocks of the Upper Cretaceous in the Moroccan Rif have been assessed and characterized in detail using organic geochemical techniques and a variety of organic geochemical parameters. The organic matter from 4 sites was studied in order to determine its thermal maturity and its depositional environments. The organic extracts (bitumens) were fractionated on silica-potassium hydroxide column according to the aliphatic hydrocarbons, acid compounds and polar compounds. Aliphatic hydrocarbons were identified by gas chromatography and mass spectrometry (GC/MS).The distribution of the aliphatic hydrocarbon fractions, and the various organic geochemical parameters (pristane/phytane, isoprenoids/n-alkanes, CPI, C₂₇:C₂₈:C₂₉ regular, C₂₉20S/(20S+20R), C₂₉ββ/(ββ+αα), C₂₉/C₃₀ hopanes and Ts/Tm) showed that the studied samples were generally mature. Two of the 4 samples appeared to be derived from source rocks deposited under anoxic conditions while suboxic to oxic conditions seemed to have been dominant for the remaining two samples. Rock–Eval pyrolysis data in addition to GC results suggested types II, III and IV kerogens for the studied samples.     

Aqueous cationic olefin polymerization using tris(pentafluorophenyl)gallium and aluminum

Tris(pentafluorophenyl)gallium ( 3 ) and aluminum ( 7 ) are active coinitiators for the production of medium‐high molecular weight (MW) polymers of styrene and isobutene (IB) under aqueous reaction conditions. Strong Brønsted acids formed in situ by reaction of these coinitiators with background moisture present in the monomer droplet ( 5 and 8 , respectively) are believed to be responsible for inducing cationic polymerization of these monomers. Of the two, 7 is the most active for IB polymerization in both aqueous media and anhydrous aliphatic solvents. These results are in contradistinction to tris(pentafluorophenyl)boron ( 2 ), which is incapable of polymerizing IB in aqueous or aliphatic media. The MWs of the polyisobutenes (PIBs) produced under aqueous conditions by either coinitiator greatly exceed those formed under similar reaction conditions by the strongly acidic chelating diborane (1,2‐C₆F₄[B(C₆F₅)₂]₂, 1 ) or diborole (1,2‐C₆F₄[9‐BC₁₂F₈]₂, 6 ). Both 3 and 7 are readily synthesized from the corresponding Group 13 halide compounds in conjunction with bis(pentafluorophenyl)zinc ( 4 ). Aqueous polymerization of IB dissolved in aliphatic solvents with 3 or 7 can yield PIBs with relatively narrow polydispersities. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Stepwise pyrolysis of macerals

Kerogen separates which consist predominantly of single maceral types at maturity levels lower than 0.7% vitrinite reflectance (R ₀) were pyrolysed in a single step and stepwise between 50 and 600°C. The total hydrocarbon yield and the yield of hydrocarbon gases (C₁−C₄) were determined along with the detailed composition of the gaseous fraction (C₁−C₄ alkanes and alkenes) and the C₅₊-fraction. The distribution of hydrocarbons, particularly in the C₁−C₃ range and the alkene/alkane ratio are useful as specific indicators for the various maceral types. The residue was analysed by reflected white light and fluorescence microscopy. The different types of reactive macerals i.e. algae, altered algae, particulate liptinites, amorphous liptinites and amorphous humic matter are transformed into particular types of inertinite. The reconstruction of the original maceral composition from its residue after katagenesis in a natural assemblage seems however difficult, due to the small amount of residue of the reactive macerals and the presence of original inertinite. Qualitative and quantitative data derived from these pyrolysis experiments may be useful on a comparative basis for the prediction of hydrocarbon generation by these maceral groups during katagenesis. Dedicated to Professor Lisa Heller-Kallai on the occasion of her 65^th birthday     

Investigation of the evolved gases from Sulcis coal during pyrolysis under N2 and H2 atmospheres

The evolution of gases and volatiles during Sulcis coal pyrolysis under different atmospheres (N₂ and H₂) was investigated to obtaining a clean feedstock of combustion/gasification for electric power generation. Raw coal samples were slowly heated in temperature programmed mode up to 800 °C at ambient pressure using a laboratory-scale quartz furnace coupled to a Fourier transform infrared spectrometer (FTIR) for evolved gas analysis. Under both pyrolysis and hydropyrolysis conditions the evolution of gases started at temperature as low as 100 °C and was mainly composed by CO and CO₂ as gaseous products. With increasing temperature SO₂, COS, and light aliphatic gases (CH₄ and C₂H₄) were also released. The release of SO₂ took place up to 300 °C regardless of the pyrolysis atmosphere, whilst the COS emissions were affected by the surrounding environment. Carbon oxide, CO₂, and CH₄ continuously evolved up to 800 °C, showing similar release pathways in both N₂ and H₂ atmospheres. Trace of HCNO was detected at low pyrolysis temperature solely in pure H₂ stream. Finally, the solid residues of pyrolysis (chars) were subjected to reaction with H₂ to produce CH₄ at 800 °C under 5.0 MPa pressure. The chars reactivity was found to be dependent on pyrolysis atmosphere, being the carbon conversions of 36% and 16% for charN₂ and charH₂, respectively.     

H2气氛下褐煤快速热解过程中CH4逸出规律的分析

在带有输送煤样的管式反应器上进行了霍林河褐煤加压快速氢解实验,分析了H₂对煤/半焦的化学键断裂和对CH₄生成规律的影响。在加压快速氢解条件下,CH₄产率随着热解温度升高、压力的增大而增大;在50% H₂气氛下,操作压力为1.0 MPa、温度为900 ℃时,CH₄产率为8.08%,达到最大,较N₂气氛下的提高了72.5%。H₂或H·自由基诱发了芳环的开裂、侧链、脂肪链和醚键的断裂,促进了煤热解。CH₄产率的增加主要是由于外部供H的结果;热解温度低于700 ℃时,H₂对煤结构中活性基团的作用促进了煤热解,导致了CH₄产率的增加;而热解温度高于700 ℃后,煤/半焦加氢气化促进了CH₄产率的增加。     

Interaction of 1,3,2,4‐Benzodithiadiazines with Aromatic Phosphines and Phosphites

Although an interaction between hydrocarbon and fluorocarbon 1,3,2,4‐benzodithiadiazines ( 1 ) and P(C₆H₅)₃ continuously produces chiral 1,2,3‐benzodithiadiazol‐2‐yl iminophosporanes ( 2 ; in this work, 5,7‐difluoro derivative 2a ) via 1:1 condensation, an interaction between 1 and other PR₃ reagents gives different products. With R  OC₆H₅ and both hydrocarbon and fluorocarbon 1 , only X=P(OC₆H₅)₃ (X = S, O) were identified in the complex reaction mixtures by ¹³С and ³¹Р NMR and GC‐MS. With R = C₆F₅, no interaction with the archetypal 1 was observed but catalytic addition of atmospheric water to the heterocycle afforded 2‐amino‐N‐sulfinylbenzenesulfenamide ( 4 ). With electrophilic B(C₆F₅)₃ instead of nucleophilic P(C₆F₅)₃, only adduct H₃N→B(C₆F₅)₃ and a new polymorph of C₆F₅B(OH)₂ were isolated and identified by X‐ray diffraction (XRD). A molecular structure of 2a was confirmed by XRD, and the π‐stacked orientation of one of phenyl groups and heterocyclic moiety was observed. This structure is in general agreement with that calculated at the RI‐MP2 level of theory, as well as at three different levels of DFT theory with the PBE and B3LYP functionals. Mild thermolysis of 2a in a dilute decane solution gave persistent 5,7‐difluoro‐1,2,3‐benzodithiazolyl ( 3a ) identified by EPR in combination with DFT calculations.     

K3Eu5(PO4)6: hydrothermal synthesis,crystal structure and photoluminescence properties

An anhydrous orthophosphate, K₃Eu₅(PO₄)₆ (tripotassium pentaeuropium hexaphosphate), has been prepared by a high‐temperature solid‐state reaction combined with hydrothermal synthesis, and its crystal structure was determined by single‐crystal X‐ray diffraction analysis (SC‐XRD). The results show that the compound crystallizes in the monoclinic space group C2/c and the structure features a three‐dimensional framework of [Eu₅(PO₄)₆]_∞, with the tunnel filled by K⁺ ions. The IR spectrum, UV–Vis spectrum and luminescence properties of polycrystalline samples of K₃Eu₅(PO₄)₆, annealed at temperatures of 650, 700, 750, 800 and 850 °C, were investigated. Although with a full Eu³⁺ concentration (9.96 × 10²¹ ions cm^?3), the self‐activated phosphor K₃Eu₅(PO₄)₆ shows s strong luminescence emission intensity with a quantum yield of 37%. Under near‐UV light excitation (393 nm), the series of samples shows the characteristic emissions of Eu³⁺ ions in the visible region from 575 to 715 nm. The sample sintered at 800 °C gives the strongest emission and its lifetime sintered at 800 °C (1.88 ms) is also the longest of all.     

The B(C6F5)3 Boron Lewis Acid Route to Arene‐Annulated Pentalenes

4,5‐Dimethyl‐1,2‐bis(1‐naphthylethynyl)benzene ( 12 ) undergoes a rapid multiple ring‐closure reaction upon treatment with the strong boron Lewis acid B(C₆F₅)₃ to yield the multiply annulated, planar conjugated π‐system 13 (50 % yield). In the course of this reaction, a C₆F₅ group was transferred from boron to carbon. Treatment of 12 with CH₃B(C₆F₅)₂ proceeded similarly, giving a mixture of 13 (C₆F₅‐transfer) and the product 15 , which was formed by CH₃‐group transfer. 1,2‐Bis(phenylethynyl)benzene ( 8 a ) reacts similarly with CH₃B(C₆F₅)₂ to yield a mixture of the respective C₆F₅‐ and CH₃‐substituted dibenzopentalenes 10 a and 16 . The reaction is thought to proceed through zwitterionic intermediates that exhibit vinyl cation reactivities. Some B(C₆F₅)₃‐substituted species ( 26 , 27 ) consequently formed by in situ deprotonation upon treatment of the respective 1,2‐bis(alkynyl)benzene starting materials ( 24 , 8 ) with the frustrated Lewis pair B(C₆F₅)₃/P(o‐tolyl)₃. The overall formation of the C₆F₅‐substituted products formally require HB(C₆F₅)₂ cleavage in an intermediate dehydroboration step. This was confirmed in the reaction of a thienylethynyl‐containing starting material 21 with B(C₆F₅)₃, which gave the respective annulated pentalene product 23 that had the HB(C₆F₅)₂ moiety 1,4‐added to its thiophene ring. Compounds 12 – 14 , 23 , and 26 were characterized by X‐ray diffraction.     

Balancing high thermal stability with high activity in diaryliminoacenaphthene‐nickel(II) catalysts for ethylene polymerization

The N,N‐diaryliminoacenaphthenes, 1,2‐[2,4‐{(4‐FC₆H₄)₂CH}₂‐6‐MeC₆H₄N]₂‐C₂C₁₀H₆ ( L1 ) and 1‐[2,4‐{(4‐FC₆H₄)₂CH}₂‐6‐MeC₆H₄N]‐2‐(ArN)C₂C₁₀H₆ (Ar = 2,6‐Me₂C₆H₃ L2 , 2,6‐Et₂C₆H₃ L3 , 2,6‐i‐Pr₂C₆H₃ L4 , 2,4,6‐Me₃C₆H₂ L5 , 2,6‐Et₂‐4‐MeC₆H₂ L6 ), incorporating at least one N ?2,4‐bis(difluoro benzhydryl)‐6‐methylphenyl group, have been synthesized and fully characterized. Interaction of L1 – L6 with (DME)NiBr₂ (DME = 1,2‐dimethoxyethane) generates the corresponding nickel(II) bromide N,N‐chelates, L NiBr₂ ( 1 – 6 ), in high yield. The molecular structures of 3 and 6 reveal distorted tetrahedral geometries at nickel with the ortho‐substituted difluorobenzhydryl group providing enhanced steric protection to only one side of the metal center. On activation with various aluminum alkyl co‐catalysts, such as methylaluminoxane (MAO) or Et₂AlCl, 1 – 6 displayed outstanding activity toward ethylene polymerization (up to 1.02 × 10⁷ g of PE (mol of Ni)^?1 h^?1). Notably 1 , bearing equivalent fluorobenzhydryl‐substituted N‐aryl groups, was able in the presence of Et₂AlCl to couple high activity with exceptional thermal stability generating high molecular weight branched polyethylenes at temperatures as high as 100 °C. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 1971–1983     

Effects of pretreatment temperature on the analysis of size-fractionated aerosol particles using ToF-SIMS

Size-fractionated aerosol particles were collected with a MOUDI 10-stage cascade impactor from an urban roadside place in a downtown area of Hong Kong. Fine aerosol particulate samples from stage 6 (aerodynamic particle diameter between 0.56 and 1 μm) and stage 9 (aerodynamic particle diameter between 0.10 and 0.18 μm) were pretreated at a chosen temperature, including −100°C, −50°C, 25°C, and 60°C, in a load lock chamber and then analyzed using time-of-flight secondary ion mass spectrometry (ToF-SIMS) at the same temperature (−100°C). Principal component analysis (PCA) was applied to further analyze ToF-SIMS spectra of aerosol particles with different pretreatment temperatures from two selected stages. ToF-SIMS results showed that the intensities of aliphatic hydrocarbon ions such as C₄H₇⁺ and C₄H₉⁺ and amine ions such as C₂H₈N⁺ and C₄H₁₂N⁺ decreased with an increase of the pretreatment temperature under ultrahigh vacuum conditions. We have shown that analyses of this type of aerosol particles using ToF-SIMS should not be conducted at ambient temperature but at low temperature (eg, −50°C). In addition, we also developed a procedure that can be used to analyze aerosol particle samples under ultrahigh vacuum environment.     

Catalytic Ethanolysis of Kraft Lignin into High‐Value Small‐Molecular Chemicals over a Nanostructured α‐Molybdenum Carbide Catalyst

We report the complete ethanolysis of Kraft lignin over an α‐MoC_1?x/AC catalyst in pure ethanol at 280 °C to give high‐value chemicals of low molecular weight with a maximum overall yield of the 25 most abundant liquid products (LP25) of 1.64 g per gram of lignin. The LP25 products consisted of C₆–C₁₀ esters, alcohols, arenes, phenols, and benzyl alcohols with an overall heating value of 36.5 MJ kg^?1. C₆ alcohols and C₈ esters predominated and accounted for 82 wt % of the LP25 products. No oligomers or char were formed in the process. With our catalyst, ethanol is the only effective solvent for the reaction. Supercritical ethanol on its own degrades Kraft lignin into a mixture of small molecules and molecular fragments of intermediate size with molecular weights in the range 700–1400, differing in steps of 58 units, which is the weight of the branched‐chain linkage C₃H₆O in lignin. Hydrogen was found to have a negative effect on the formation of the low‐molecular‐weight products.     

Sorption and transport of hydrocarbon and perfluorocarbon gases in poly(1‐trimethylsilyl‐1‐propyne)

Pure gas solubility and permeability of H₂, O₂, N₂, CO₂, CH₄, C₂H₆, C₃H₈, CF₄, C₂F₆, and C₃F₈ in poly(1‐trimethylsilyl‐1‐propyne) (PTMSP) were determined as a function of pressure at 35°C. Permeability coefficients of the perfluorinated penetrants are approximately an order of magnitude lower than those of their hydrocarbon analogs, and lower even than those of the permanent gases. In striking contrast to hydrocarbon penetrants, PTMSP permeability to fluorocarbon penetrants decreases with increasing penetrant size. This unusual size‐sieving behavior in PTMSP is attributed to low perfluorocarbon solubilities in PTMSP coupled with low diffusion coefficients relative to those of their hydrocarbon analogs. In general, perfluorocarbon penetrants are less soluble than their hydrocarbon analogs in PTMSP. The difference in hydrocarbon and perfluorocarbon solubilities in high free volume, hydrocarbon‐rich PTMSP is much smaller than in hydrocarbon liquids and liquidlike polydimethylsiloxane. The low solubility of perfluorocarbon penetrants is ascribed to the large size of the fluorocarbons, which inhibits their dissolution into the densified regions of the polymer matrix and reduces the number of penetrant molecules that can be accommodated in Langmuir sites. From the permeability and sorption data, diffusion coefficients were calculated as a function of penetrant concentration. With the exception of H₂ and the C₃ analogs, all of the penetrants exhibit a maximum in their concentration‐dependent diffusion coefficients. Resolution of diffusion coefficients into a mobility factor and a thermodynamic factor reveals that it is the interplay between these two terms that causes the maxima. The mobility of the smaller penetrants (H₂, O₂, N₂, CH₄, and CO₂) decreases monotonically with increasing penetrant concentration, suggesting that the net free volume of the polymer–penetrant mixture decreases as additional penetrant is added to PTMSP. For larger penetrants mobility either: (1) remains constant at low concentrations and then decreases at higher penetrant concentrations (C₂H₆, CF₄, and C₂F₆); (2) remains constant for all concentrations examined (C₃H₈); or (3) increases monotonically with increasing penetrant concentration (C₃F₈). Presumably these results reflect the varying effects of these penetrants on the net free volume of the polymer–penetrant system. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 273–296, 2000     

Comparison of Properties of Carbon Particles Formed by Pyrolysis of C3O2 and C2H2 behind Shock Waves

Various carbon particles formed by the pyrolysis of C₃O₂ and C₂H₂ behind shock waves in the temperature range 1200–3800 K are studied. The formation of the condensed carbon particles is observed directly by the multichannel detection of the time profiles of the extinction of the medium in the UV, visible, and near-IR spectral regions. The samples of carbon material deposited on the walls of a shock tube after an experiment are analyzed using transmission electron microscopy with different resolutions and electron microdiffraction. Particles formed from C₃O₂ and C₂H₂ at 1500–2000 K are 10–30 nm in size and look like usual soot. The absence of molecular hydrogen in C₃O₂ only results in faster formation and graphitization. At 2100–2600 K, the formation of particles is retarded, and the yield of the carbon particles decreases for both substances. After experiments on pyrolysis of C₃O₂ at these temperatures, giant spherical particles up to 700 nm in size are found on the walls of the shock tube. Carbon particles formed at the highest temperatures (2700–3200 K) in C₃O₂ pyrolysis have the high degree of crystallinity of particles.     

Borane Adducts of Hydrazoic Acid and Organic Azides: Intermediates for the Formation of Aminoboranes

The reaction of HN₃ with the strong Lewis acid B(C₆F₅)₃ led to the formation of a very labile HN₃?B(C₆F₅)₃ adduct, which decomposed to an aminoborane, H(C₆F₅)NB(C₆F₅)₂, above ?20 °C with release of molecular nitrogen and simultaneous migration of a C₆F₅ group from boron to the nitrogen atom. The intermediary formation of azide–borane adducts with B(C₆F₅)₃ was also demonstrated for a series of organic azides, RN₃ (R=Me₃Si, Ph, 3,5‐(CF₃)₂C₆H₃), which also underwent Staudinger‐like decomposition along with C₆F₅ group migration. In accord with experiment, computations revealed rather small barriers towards nitrogen release for these highly labile azide adducts for all organic substituents except R=Me₃Si (m.p. 120 °C, T_dec=189 °C). Hydrolysis of the aminoboranes provided C₆F₅‐substituted amines, HN(R)(C₆F₅), in good yields.     

Gas sorption,diffusion, and permeation in poly(dimethylsiloxane)

The permeability of poly(dimethylsiloxane) [PDMS] to H₂, O₂, N₂, CO₂, CH₄, C₂H₆, C₃H₈, CF₄, C₂F₆, and C₃F₈, and solubility of these penetrants were determined as a function of pressure at 35 °C. Permeability coefficients of perfluorinated penetrants (CF₄, C₂F₆, and C₃F₈) are approximately an order of magnitude lower than those of their hydrocarbon analogs (CH₄, C₂H₆, and C₃H₈), and the perfluorocarbon permeabilities are significantly lower than even permanent gas permeability coefficients. This result is ascribed to very low perfluorocarbon solubilities in hydrocarbon‐based PDMS coupled with low diffusion coefficients relative to those of their hydrocarbon analogs. The perfluorocarbons are sparingly soluble in PDMS and exhibit linear sorption isotherms. The Flory–Huggins interaction parameters for perfluorocarbon penetrants are substantially greater than those of their hydrocarbon analogs, indicating less favorable energetics of mixing perfluorocarbons with PDMS. Based on the sorption results and conventional lattice solution theory with a coordination number of 10, the formation of a single C₃F₈/PDMS segment pair requires 460 J/mol more energy than the formation of a C₃H₈/PDMS pair. A breakdown in the geometric mean approximation of the interaction energy between fluorocarbons and hydrocarbons was observed. These results are consistent with the solubility behavior of hydrocarbon–fluorocarbon liquid mixtures and hydrocarbon and fluorocarbon gas solubility in hydrocarbon liquids. From the permeability and sorption data, diffusion coefficients were determined as a function of penetrant concentration. Perfluorocarbon diffusion coefficients are lower than those of their hydrocarbon analogs, consistent with the larger size of the fluorocarbons. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 415–434, 2000     

Organometallic Molybdenum(V) Complexes with Primary Phosphine Ligands. Syntheses,Spectroscopic Properties and Molecular Structures of [Cp°MoCl4(PH2R)] (R = But, 1‐Ad,Cy, Ph, 2, 4, 6‐Me3C6H2, 2, 4, 6‐Pri3C6H2, Cp° = C5EtMe4)

[Cp°MoCl₄] (Cp° = C₅EtMe₄) reacts with primary phosphines PH₂R to give the paramagnetic phosphine complexes [Cp°MoCl₄(PH₂R)] [Cp° = C₅EtMe₄, R = Bu^t ( 1 ), 1‐Ad (1‐Ad = 1‐adamantyl; 2 ), Cy ( 3 ), Ph ( 4 ), Mes (Mes = 2, 4, 6‐Me₃C₆H₂; 5 ), Tipp (Tipp = 2, 4, 6‐Prⁱ₃C₆H₂; 6 )]. 1 — 6 were characterized spectroscopically (IR, MS), and X‐ray crystal structures were determined for 1 — 4 and 6 . EPR investigations in liquid and frozen solution confirmed the presence of Mo^V species, and the data were used to analyze the spin‐density distribution in the first coordination sphere. Complexes 3 and 4 react with two equivalents of NEt₃ with formation of [Cp°MoCl₂(η³‐P₄Cy₄H)] ( 7 ) and [Cp°₂Mo₂(μ‐Cl)₂(μ‐P₄Ph₄)] ( 8 ), respectively, in low yield. Complexes 7 and 8 were characterized by X‐ray crystallography.     

Electrochemically reduced tungsten‐based active species as catalysts for cross‐metathesis reactions: cross‐metathesis of erucic acid with 2‐octene

The cross‐metathesis of erucic acid, (CH₃(CH₂)₇CH?CH(CH₂)₁₁COOH), with an excess of 2‐octene in the presence of an electrochemically produced tungsten‐based catalyst has been studied. Cross‐ and self‐hydrocarbon products, viz. 2‐undecene (C₁₁), 6‐dodecene (C₁₂) and 6‐pentadecene (C₁₅), were detected. The influence of several parameters, such as the 2‐octene/erucic acid and 2‐octene/catalyst ratios and the reaction time, on the yield of the cross‐metathesis product, 6‐pentadecene, was studied. The cross‐metathesis of functionalized olefins in the presence of an Al–e^?–WCl₆–CH₂Cl₂ system has not been reported in the literature so far. The cross‐metathesis products in the presence of this catalyst system can be obtained with high yield and high specificity. Copyright © 2004 John Wiley & Sons, Ltd.