Isomerization and anti-Markovnikov arylation of olefin catalyzed by an iridium complex

An iridium acetylacetonato complex, a catalyst for anti-Markovnikov arylation of olefins, was found to work as a catalyst for olefin isomerization. 2-butene was obtained with 0.55 cis/trans ratio in isomerization of 1-butene. Moreover, in 1-hexene/benzene solution, isomerization and arylation of 1-hexene were simultaneously catalyzed by the iridium complex.     

Vapor-Liquid equilibria measurement of carbon dioxide+1-hexene and carbon dioxide+2-ethyl-1-butene systems at high pressure

Pressure-composition isotherms were obtained for the carbon dioxide+1-hexene system at 40, 60, 80, 100 and 120 ‡C and pressure up to 120 bar and for carbon dioxide+2-ethyl-1-butene system at 40, 75 and 100 ‡C and pressure up to 115 bar. The accuracy of the experimental apparatus was tested by comparing the measured phase equilibrium data of the carbon dioxide+ 1-hexene system at 40 ‡C and 60 ‡C with those of Wagner and Wichterle [1987], and Jennings and Teja [1989]. The solubility of 1-hexene and 2-ethyl-1-butene for the carbon dioxide + 1-hexene and carbon dioxide+2-ethyl-1-butene systems increases as the temperatures increases at constant pressure. These two carbon dioxide-polar solute systems exhibit type-I phase behavior, which is characterized by an uninterrupted critical mixture curve that has a maximum in pressure. The experimental data are modeled by using the Peng-Robinson equation of state. A good fit of the data is obtained with Peng-Robinson equation of state using two adjustable parameters for carbon dioxide+1-hexene and carbon dioxide+2-ethyl-1-butene systems.     

IR study of adsorption and reaction of 1-butene on H-ZSM-5

Adsorption and reaction of 1-butene on H-ZSM-5 were studied by FT-IR spectroscopy. The adsorbed 1-butenes were converted to cis- and trans-2-butenesbelow 250 K under evacuation, and dimerization of the adsorbed 2-butenes was observed at room temperature. The produced dimer was tentatively assigned to3,4-dimethyl-3-hexene which hydrogen-bonded to the acidic OH groups with its alkyl chains. Therefore, the reaction terminated at the dimerization since proton transfer from H-ZSM-5 to the dimer did not occur. This revised version was published online in July 2006 with corrections to the Cover Date.     

1-丁烯共聚的研究进展

从少量1-丁烯改性聚烯烃和其他α-烯烃改性聚1-丁烯二个方面综述了1-丁烯与乙烯、丙烯、1-己烯、亚乙基降冰片烯、苯乙烯的共聚以及乙丙丁三元共聚的研究进展,指出了1-丁烯共聚技术的研究方向。     

Compatibility of binary blends of polypropylene with ethylene-α-olefin copolymer

The compatibility for binary blends of isotactic polypropylene with rubbery ethylene-α-olefin copolymers having various α-olefin contents was investigated by means of differential scanning calorimetry, X-ray analysis, transmission electron microscopy, and dynamic mechanical analysis. It was found that “α-olefin rich” in ethylene-1-butene copolymers and in ethylene-1-hexene copolymers were miscible with amorphous polypropylene chains, when the α-olefin content is above 50 mol %. On the other hand, the blends with “ethylene rich” (above 50 mol % of the ethylene content) in ethylene-1-butene copolymers and ethylene-1-hexene copolymers showed a microheterogeneous morphology. © 1996 John Wiley & Sons, Inc.     

聚1-丁烯弹性体及1-丁烯与1-己烯共聚弹性体的流变性能

采用恒速双筒毛细管流变仪研究了自制的聚1-丁烯热塑性弹性体(PB-TPE)及1-丁烯与1-己烯共聚弹性体(B-co-H)的流变性能.结果表明,相同条件下PB-TPE和B-co-H均为假塑性流体,B-co-H的非牛顿性更强,PB-TPE比B-co-H的黏流活化能高.随着1-己烯含量的增大,共聚物分子链柔顺性增加,加工性能...     

1-己烯共聚物HF-7042和1-丁烯共聚物DFDA-7042性能对比

采用核磁共振分析仪和差示扫描量热仪对线型低密度聚乙烯1-己烯共聚物HF-7042和1-丁烯共聚物DFDA-7042进行了对比分析,研究了HF-7042与DFDA-7042的性能差别。结果表明,在密度和熔体质量流动速率接近的情况下,HF-7042的共聚单体摩尔分数低于DFDA-7042,HF-7042的熔融特性(包括结晶温度、熔融温度、结晶度和片晶厚度)高于DFDA-7042,HF-7042的拉伸性能优于DFDA-7042。     

Hydrogenation of 1,3-butadiene on platinum surfaces of different structures

1,3-butadiene hydrogenation is studied on platinum foil and Pt(111), Pt(100), Pt(755) single-crystal surfaces at 300--375 K. The results are compared with the data of alkene hydrogenation reactions. Similar to the hydrogenation kinetics of butenes, 1,3-butadiene hydrogenation exhibits near zeroth-order dependence on hydrocarbon and near first-order dependence on hydrogen pressure. With the same hydrocarbon (3.5-70 Torr) and hydrogen (14-140 Torr) pressure, the rate of 1,3-butadiene hydrogenation is one order of magnitude lower than for the rates for n-butenes. The hydrogenation products include 1-butene, trans- and cis-2-butene, and n-butane. The reaction selectivity is independent of reactant mixture and platinum surface structure, but changes slightly as a function of reaction temperature. The butene product distribution is determined by surface reaction kinetics. While 1-butene is thermodynamically less stable than trans- and cis-2-butene, it is the major butene product in 1,3-butadiene hydrogenation. This revised version was published online in July 2006 with corrections to the Cover Date.     

Ethylene and mixed 2-butene cis/trans isomers metathesis: Influence of lanthanum as a second metal on the WO3/SiO2 catalysts

Lanthanum (0.5, 0.6, 0.75, 0.9 and 1 wt%) was added as a second metal on the 9 wt% WO₃/SiO₂ catalysts by the incipient wetness impregnation method. The catalysts were tested in the metathesis reaction of ethylene and 2-butene using either pure 2% trans-2-butene and the mixture of 1% cis- and 1% trans-2-butene as the reaction feed and were characterized by X-ray diffraction (XRD), nitrogen physisorption (BET), inductively coupled plasma optical emission spectrometry (ICP-OES), scanning electron microscopy, ion-exchange titration, FT-Raman, ammonia temperature programmed desorption (NH₃-TPD) and reactant temperature programmed desorption (reactant-TPD). An optimum lanthanum loading at 0.5 wt% could improve dispersion of tungsten active phase and adsorption properties of the reactants on the catalysts. The adsorption of the mixed cis/trans-2-butene isomer was much improved on the La-WO₃/SiO₂ catalysts with 0.5 wt% La.     

Preparation of co-dimers of styrene and p-chlorostyrene with regulated monomer sequences using phosphates

Polymer Bulletin - Two co-dimers of styrene and p-chlorostyrene having regulated monomer sequences were obtained by the reactions of 1-(4-chlorophenyl) ethyl diphenyl phosphate with styrene and of...     

Does the length of the short chain branch affect the mechanical properties of linear low density polyethylenes? An investigation based on films of copolymers of ethylene/1-butene, ethylene/1-hexene and ethylene/1-octene synthesized by a single site metallocene catalyst

Three nearly identical linear low density polyethylene resins based on copolymers of ethylene with 1-butene (B), 1-hexene (H) and 1-octene (O) were utilized to investigate the effect of short chain branch length on the mechanical properties of blown and compression molded (quenched and slow cooled) films. The content of short chain comononer in the three copolymers was ca. 2.5-2.9 mol% that corresponded to a density of 0.917-0.918 g/cm³. Within a given series, the tensile properties of these films do not show any significant difference at slow deformation rates (up to 510 mm/min), even though the DSC and TREF profiles of ‘H’ and ‘O’ differed slightly in comparison to ‘B’. However, at higher deformation rates (ca. 1 m/s), the breaking strength of these films was found to increase with increasing short chain branch length. In addition, the Spencer impact and Elmendorf tear strength of the blown films were also observed to increase with increasing short chain branch length. Further, dart impact strength and high-speed puncture resistance (5.1 m/s) of 1-octene and 1-hexene based samples was also observed to be higher than that based on 1-butene. The blown films displayed low and comparable levels of equivalent in-plane birefringence and crystalline orientation by wide angle X-ray scattering. This confirms that the differences in mechanical properties in the blown film series are not attributable to differences in molecular orientation. The deformation behavior of both the compression molded and blown films were also investigated in a well-defined controlled regime by analyzing their essential work of fracture. It was found that the essential work of fracture of films based on 1-hexene and 1-octene was higher than that of films based on 1-butene. While the origin of these differences in mechanical properties with increasing short chain branch length is not fully understood, the present investigation confirms this effect to be pronounced at high deformation rates for both the blown and compression molded quenched films.     

Effect of short chain branching on the blown film properties of linear low density polyethylene

Three linear low density polyethylene (LLDPE) resins of similar melt index and density were synthesized with different comonomers in the Unipol pilot-plant scale reactor. The molecular structure, blown film morphology, and film strength properties of the resins have been comprehensively characterized. The film dart drop impact strength of the LLDPEs increases in the order of ethylene/1-butene, ethylene/1-octene, and ethylene/1-hexene copolymers; whereas the Elmendorf tear strength of them increases in the order of ethylene/1-butene, ethylene/1-hexene, and ethylene/1-octene copolymers. The mechanical properties seem to be highly associated with the length and distribution of short chain branches and, consequently, the lamellar thickness distribution of the resins. © 1996 John Wiley & Sons, Inc.     

Effect of comonomer partitioning on the kinetics of mesophase formation in random copolymers of propene and higher α-olefins

The effect of counit type on the kinetics of mesophase formation has been investigated by means of chip-calorimetry in propene/α-olefin random copolymers, containing counits which show large differences in their co-crystallization behavior with propene, i.e. 1-butene and 1-hexene. Non-isothermal crystallization experiments indicated that the minimum cooling rate at which mesophase formation is observed is directly related to the kinetic of α-phase crystallization, which is lower for the copolymer with the bulkier 1-hexene counit. Isothermal structuring was probed in a wide temperature range, revealing that a double bell-shaped curve is required to describe the temperature dependence of crystallization times of the two polymorphs. The ordering kinetics of the mesophase is the fastest in i-PP homopolymer and decreases with increasing comonomer bulkiness, analogous to what happens for the monoclinic phase. The results are discussed by considering the effect of comonomer on the driving force for mesophase formation, also at the light of new WAXD and density evidences, which prove different extents of inclusion of 1-butene and 1-hexene in the ordered phases.     

Nonvolatilealpha-branched chain fatty esters. II

A group of nonvolatilealpha-branched esters was prepared by the di-tertiary butyl peroxide-promoted addition of normal esters to terminal olefins containing methyl branches or aryl groups. Methyl stearate was added to 3,7-dimethyl-1-octene, 3,5,5-trimethyl-1-hexene, and 4-phenyl-1-butene. The reaction with 2,4,4-trimethyl-1-pentene, a terminal alkene with a methyl branch at the internal ethylenic carbon, was not successful. Benzyl 2-(4-phenylbutyl) octadecanoate was prepared by transesterification of the corresponding methyl ester. Benzyl 2,2-dimethylpropanoate, which has no α-hydrogen in the acyl portion of the molecule, was added to 1-hexadecene to form α-hexadecylbenzyl 2,2-dimethylpropanoate. Lubricant evaluation data were obtained on the above compounds. Presented at the AOCS Meeting, New Orlenas, May 1967. E. Utiliz. Res. Dev. Div., ARS, USDA.     

反式-9,10-二氢-9,10-二对甲苯基-9,10-菲二醇包结性能的研究

合成了主体分子反式-9,10-二氢-9,10-二对甲苯基-9,10-菲二醇(1),它可以和苯、喹啉形成晶体包结物,通过m.p.、IR、粉末XRD对它们进行了表征,通过^1HNMR积分计算包结物主客体物质的量比分别为：n1：n苯=3：2;n1：n喹啉=1：1。     

Separation of propene/1-alkene and ethylene/1-alkene copolymers by high-temperature adsorption liquid chromatography

A high performance liquid chromatography column (HPLC) Hypercarb^® packed with porous graphite has proven to discriminate polyolefin molecules due to differences in their adsorption and desorption behaviour. While linear polyethylene (PE) and syndiotactic polypropylene (sPP) are adsorbed on the graphite packing, isotactic polypropylene (iPP) is not adsorbed. The column operates at 160 °C with 1-decanol as sample solvent and mobile phase. We have now tested this HPLC system for separations of random propene/1-alkene and ethylene/1-hexene copolymers: While copolymers of propene with 1-butene, 1-hexene and 1-octene copolymers eluted in size exclusion mode without adsorption, propene/1-octadecene and ethylene/1-hexene copolymers are strongly retained and eluted only after application of a linear gradient starting from 1-decanol and ending with pure 1,2,4-trichlorobenzene. The retention of propene/1-alkene (>11 carbons in the side chain) copolymers increases with the concentration of comonomer, making this HPLC system suitable to separate these copolymers according to their chemical composition. In contrast, the retention of ethylene/1-hexene samples decreases with increasing 1-hexene content. Branching in this case shortens the length of continuous methylene sequences of the polymer backbone, which are expected to adsorb in a planar conformation to the graphite layers. This is the first report on the separation of short chain branched polyolefins by high-temperature adsorption liquid chromatography.     

Selectivity controlling in the hydrogenation of 1,3-butadiene on Tl-modified Pd catalyst

The selectivity and reactivity in the hydrogenation of 1,3-butadiene catalyzed by Tl-modified 5 wt% Pd/Al₂O₃ catalysts vary with amounts of Tl loading and with the reduction temperatures, that is, the main product was 1-butene and trans-2-butene for values of Tl loading of 0.5 and 2 in Tl/Pd atomic ratio, respectively, when the catalysts were reduced at 673 K. 1,3-butadiene was hydrogenated selectively towards 1-butene and trans-2-butene when the Tl modified 5 wt% Pd/Al₂O₃ catalyst of Tl/Pd = 2 was reduced at 300 and 373 K or above, respectively. On the catalyst with Tl/Pd = 2 reduced at 373 K or above, the butenes formed are not hydrogenated to butane, even after a long reaction time. These results suggest the formation of Pd-Tl alloy or intermetallic compounds during the reduction procedure which is responsible for the selectivity controlling in the reaction. TPR and XRD results were in consistence with the reaction data.     

A process for the simultaneous oligomerization and copolymerization of ethylene

High density polyethylene becomes more flexible and tough by adding short branches onto the otherwise linear backbone. Commercially, this is achieved by adding 1-butene or 1-hexene comonomer to reactor and copolymerizing it with ethylene. A process has now been developed which uses low pressure to produce new forms of branched polyethylene without addition of comonomer to the reaction mixture.     

Lamellar morphology of random metallocene propylene copolymers studied by atomic force microscopy

Four sets of propylene based random copolymers with co-units of ethylene, 1-butene, 1-hexene and 1-octene, and a total defect content up to ∼9 mol% (including co-unit and other defects), were studied after rapid and isothermal crystallization. Etched film surfaces and ultramicrotomed plaques were imaged so as to enhance contrast and minimize catalyst and co-catalyst residues. While increasing concentration of structural irregularities breaks down spherulitic habits, the formation of the gamma polymorph has a profound effect on the lamellar morphology. Lamellae grown in the radial axis of the spherulite and branches hereon are replaced in γ-rich copolymers with a dense array of short lamellae transverse or tilted to the main structural growth axis. This is the expected orientation for γ iPP branching from α seeds. Spherulites are formed in copolymers with non-crystallizable units (1-hexene and 1-octene) up to ∼3 mol% total defect content and were observed up to ∼6 mol% in those with partially crystallizable comonomers (ethylene and 1-butene). However, lamellae were observed in all the copolymers analyzed, even in the most defective ones, highlighting the important role of the gamma polymorph in propagating lamellar crystallites in poly(propylenes) with a high concentration of defects. Long periods measured from AFM and SAXS are comparatively analyzed.     

A kinetic study of catalytic butane dehydrogenation

A study was made of the dehydrogenation of n-butane over a commercial chromia-alumina catalyst. Dehydrogenation runs were performed at 500°C. and space velocity of 34,000 hr^?1 over a range of butane partial pressures from 0.06 to 1.80 atm. Conversions were differential, averaging about 3% (with a maximum of 6% ) of the input butane. Reaction was found to be 0.75 order in butane partial pressure. Thermodynamic equilibrium was attained among the products, which were 1-butene, cis-2-butene, and trans-2-butene. The method of Yang and Hougen showed dehydrogenation to be surface reaction controlled at a confidence level of 91%. This conclusion agrees with that of a previous study by Dodd and Watson.