- Silica-immobilized ionic liquid Br?nsted acids as highly effective heterogeneous catalysts for the isomerization of: N -heptane and n -octane
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Metal-free imidazolium-based ionic liquid (IL) Br?nsted acids 1-methyl imidazolium hydrogen sulphate [HMIM]HSO4 and 1-methyl benzimidazolium hydrogen sulphate [HMBIM]HSO4 were synthesized. Their physicochemical properties were investigated using spectroscopic and thermal techniques, including UV-Vis, FT-IR, 1H NMR, 13C-NMR, mass spectrometry, and TGA. The ILs were immobilized on mesoporous silica gel and characterized by FT-IR spectroscopy, scanning electron microscopy, Brunauer-Emmett-Teller analysis, ammonia temperature-programmed desorption, and thermogravimetric analysis. [HMIM]HSO4?silica and [HMBIM]HSO4?silica have been successfully applied as promising replacements for conventional catalysts for alkane isomerization reactions at room temperature. Isomerization of n-heptane and n-octane was achieved with both catalysts. In addition to promoting the isomerization of n-heptane and n-octane (a quintessential reaction for petroleum refineries), these immobilized catalysts are non-hazardous and save energy.
- Al-Fatesh, Ahmed S.,Dhar, Abhishek,Fakeeha, Anis H.,Ibrahim, Ahmed A.,Khimani, Mehul,Patel, Hiren,Siva Kumar, Nadavala,Vekariya, Rohit L.
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p. 15282 - 15292
(2020/05/05)
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- Conversion of n-Heptane, n-Butane, and Their Mixtures on Catalytic Systems Al2O3/WO 42– ?ZrO2 and HMOR/WO 42– ?ZrO2
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The conversion of n-C7H16, n-C4H10 and mixtures of C7H16: n-C4H10 = 1: 0.3 on the composite catalysts Al2O3/WO42– ?ZrO2 (A-WZ) and HMOR/ WO42– ? ZrO2 (M-WZ) at atmospheric pressure, H2/hydrocarbon = 3 and temperatures of 140°C-200°C was studied. A mixture of C7H16: n-C4H10 on M-WZ with high selectivity was converted into C5–C6 isomers. Systems, e.g., M-WZ can be promising catalysts for the joint processing of associated petroleum gas and gasoline into ecologically clean high-octane gasolines without aromatic components. However, the bifunctional interaction of n-heptane:n-butane was realized at certain lower temperatures.
- Abasov,Agayeva,Mamedova,Isayeva,Imanova,Iskenderova,Aliyeva,Zarbaliyev,Tagiyev
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p. 964 - 971
(2018/08/31)
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- Synthesis and functionalization of ordered mesoporous carbons supported Pt nanoparticles for hydroconversion of n-heptane
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A comprehensive study was performed on the spectroscopic and textural properties of ordered mesoporous carbon (OMC) of the CMK-3 type modified by acid oxidation using K2S2O8 as a benign oxidant and nitrogen-doping by the aid of the polymerization of ethylenediamine and carbon tetrachloride inside the pore channels of SBA-15 hard template. The pristine, nitrogen-doped, and oxidized-ordered mesoporous carbons were used as supports to prepare 10 wt% platinum nanoparticles-loaded catalysts using ethylene glycol as a reducing agent. The catalytic behavior, mechanism, and influence of the surface functionalization of the ordered mesoporous carbon bifunctional catalysts toward the hydroconversion of n-heptane using a fixed-bed flow system operated under atmospheric pressure were investigated. The synthesized samples were characterized by various analytical and spectroscopic techniques. The mesostructural regularity corresponding to the hexagonal P6mm symmetry of the OMC-CMK-3 type was well-reserved even after surface modifications replicated from an SBA-15 template. H2 pulse chemisorption and EDX mapping images confirmed differences in the Pt NPs contents and dispersion depending on the support composition. The catalytic activity results achieved were hand in hand with the proper balance between the acidity strength and Pt NPs dispersion degree.
- Said
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p. 14517 - 14529
(2018/08/28)
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- Influence of the Br?nsted acidity, SiO2/Al 2O3 ratio and Rh-Pd content on the ring opening. Part II. Selective ring opening of methylcyclohexane
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Monometallic and bimetallic Pd-Rh catalysts with various Rh/Pd atomic ratios (=0.5, 1 and 2) and a total metal charge of 1 wt% supported on SiO 2-Al2O3 (SIRAL 40, 20, 5) were studied for the ring opening of methylcyclohexane (MCH). The results were compared with those obtained previously for ring opening of decalin. It was found that the total acidity and the Br?nsted acidity of the support have a higher influence on the activity for ring opening of naphthenic bicycles than on the activity for opening single rings. The influence of the metal charge is more important on the reaction of MCH. All the catalysts display a high MCH conversion, which increases with the reaction temperature. The bimetallic catalyst with the Rh/Pd ratio equal to 2 and supported on SIRAL 40 has the highest yield to ring opening products.
- D'Ippolito, Silvana A.,Especel, Catherine,Vivier, Laurence,Epron, Florence,Pieck, Carlos L.
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p. 541 - 549
(2014/01/06)
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- Influence of chlorine on the catalytic properties of supported rhodium, iridium and platinum in ring opening of naphthenes
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Pt, Ir and Rh were deposited on SiO2 or Al2O 3 using chlorinated precursors and various amounts of HCl in the impregnation medium. The Br?nsted and Lewis acidities increased with the chlorine content of the alumina supported catalysts. The silica-supported catalysts only presented Lewis acid sites. The catalysts were evaluated in methylcyclopentane (MCP) and methylcyclohexane (MCH) ring-opening (RO) under pressure (2.85 and 3.95 MPa, respectively), from 200 to 425 C. For MCP conversion, the acidity of the alumina support had no sensitive effect on the activity and selectivity to RO products, and few effects on the distribution of RO products. No isomerization or hydrocracking products were observed, confirming that these reactions occurred mainly on the metal function, which was not modified by the presence of chlorine. The nature of the support, SiO 2 or Al2O3, had a strong effect on both the activity (1.9 against 0.5 mol h-1 g-1metal for Ir/Al2O3 and Ir/SiO2, respectively at 225 C) and selectivity to RO products (99.6% against 97.5% for Ir/Al2O 3 and Ir/SiO2, respectively, at 80% of MCP conversion) for Ir catalysts only. Interestingly, the Rh/SiO2 exhibited a high selectivity for converting MCP to RO products, similar to Ir/Al 2O3, i.e. 99.6% at 80% of conversion. Depending on the metal and the supports, three types of behavior were observed for MCH ring-opening: (i) a direct ring-opening on the metal function whatever the support for Ir, (ii) a first step of isomerization, and then a need of a sufficiently acidic support, for Pt and (iii) an intermediate behavior for Rh, which was able to either directly convert MCH in absence of acidic support or favor a bifunctional mechanism on chlorinated alumina.
- Samoila,Epron,Marécot,Especel
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p. 207 - 219
(2013/07/26)
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- A novel iron complex for cross-coupling reactions of multiple C-Cl bonds in polychlorinated solvents with grignard reagents
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A novel iron(III) complex (2) of a pincer ligand [1, N2,N6-bis(2,6- diisopropylphenyl)pyridine-2,6-dicarboxamide] was developed and used for remediation of polychlorinated solvents via sp3-sp3 coupling of Grignard reagents with C-Cl bonds. The use of an iron catalyst for such coupling reactions is highly desirable due to its greener and more economical nature. Complex 2 was characterized using various spectroscopic techniques: electrospray ionization mass spectrometer (ESI-MS, m/z 575.1), cyclic voltammetry (E 1/2, 0.03 V and ΔE, 0.97 V), and ultraviolet visible (UV/Vis) spectroscopic techniques. The iron(III) complex showed efficient activation of multiple C-Cl bonds and catalyzing C-C coupling of polychlorinated alkyl halides, such as dichloromethane (CH2Cl2), chloroform (CHCl3), and carbon tetrachloride (CCl4), with various Grignard reagents under ambient reaction conditions. Complex 2 showed exceptional activity with reactions approaching near completion in about 5 min. With the required catalyst loading as low as 0.2 mol%, considerably high turnover numbers (TON = 483) and turnover frequency (TOF = 5,800 h-1) were obtained. None of the products detected during the reaction contained any chlorine, indicating an efficient dechlorination method while synthesizing products of synthetic and commercial interest. Interestingly, the catalyst was capable of replacing all chlorine atoms in each polychlorinated solvent under the investigations with high conversion. Springer Science+Business Media, LLC 2012.
- Gartia, Yashraj,Pulla, Sharon,Ramidi, Punnamchandar,Farris, Carolina Costa,Nima, Zeid,Jones, Darin E.,Biris, Alexandru S.,Ghosh, Anindya
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p. 1397 - 1404
(2013/01/15)
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- Cross coupling reactions of multiple CCl bonds of polychlorinated solvents with Grignard reagent using a pincer nickel complex
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The nickel(II) complex of a bulky pincer-type ligand, N,N′-bis(2,6- diisopropylphenyl)-2,6-pyridinedicarboxamido, was examined for sp 3-sp3 coupling of Grignard reagents with polychlorinated solvents. The nickel(II) complex catalyzed CC coupling of polychlorinated alkyl halides, such as dichloromethane (CH2Cl2), chloroform (CHCl3), and carbon tetrachloride (CCl4), with various Grignard reagents. The effective activation of multiple CCl bonds proceeded under ambient reaction conditions and within a short time (20 min). This catalyst displays the highest activity yet reported for this reaction type, with catalyst loading as low as 0.4 mol% and turnover frequency (TOF) as high as 724 h-1. The catalyst is capable of replacing all chlorine atoms with CC bond formations for all of the polychlorinated solvents under investigation. The catalytic process could prove to be an efficient method of remediation of toxic polychlorinated solvents while generating synthetically and commercially important chemicals.
- Gartia, Yashraj,Nasini, Udaya Bhasker,Ghosh, Anindya,Biswas, Abhijit,Stadler, Matthew
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p. 322 - 327,6
(2020/07/30)
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- Hydrocarbon separation
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Process for the separation of close boiling compounds comprising distilling a hydrocarbon mixture of said compounds in the presence of a high boiling diluent liquid and a solid adsorbent. The high boiling diluent is withdrawn from the bottom of the distillation column and recycled to the column. The process is particularly suitable for the separation of straight-chain isomers from isomerate mixtures, the separation of benzene from hydrocarbon mixtures and the separation of paraffins from olefins.
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Page/Page column 11
(2008/12/06)
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- Isomerization of N-heptane in naphtha cuts
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A process for the isomerization of normal heptane contained within a naphtha stream, such as a C6-C8 naphtha, in which the naphtha stream is fractionated into a fraction substantially free of normal heptane and a fraction containing normal heptane. The fraction containing normal heptane is contacted with an isomerization catalyst in an isomerization zone operated as a singe pass fixed bed reactor having a single effluent to isomerize a portion of said normal heptane to branched heptane. The effluent is recovered from said isomerization zone and the effluent is fractionated to recover said branched heptane. The unconverted normal heptane is recovered and returned to the isomerization since it can be separated from the branded heptanes by fractionation.
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Page/Page column 4
(2008/06/13)
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- Catalyst and process for contacting a hydrocarbon and ethylene
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A process of contacting at least one feed hydrocarbon, containing three to about seven carbon atoms per molecule, and ethylene in a hydrocarbon-containing fluid in the presence of a catalyst composition to provide at least one product hydrocarbon isomer containing about four to about nine carbon atoms per molecule is provided. The at least one feed hydrocarbon can be selected from paraffins, isoparaffins, and the like and combinations thereof. The catalyst composition contains a hydrogen halide component, a sulfone component, and a metal halide component.
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- Disproportionation of hydrocarbons
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A novel hydrocarbon disproportionation process is provided and includes contacting a hydrocarbon feed comprising at least one paraffin with a disproportionation catalyst comprising a support component, a metal, and a halogen in a disproportionation reaction zone under disproportionation reaction conditions.
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- Process of paraffin hydrocarbon isomerisation catalysed by an ionic liquid in the presence of a cyclic hydrocarbon addditive
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A process for the conversion of linear and/or branched paraffins hydrocarbons, catalysed by an ionic liquid catalyst, in the presence of a cyclic hydrocarbon additive containing a tertiary carbon atom. The presence of the specific hydrocarbon additives influences the reaction mechanism by increasing the selectivity towards the formation of paraffin hydrocarbons with a higher degree of branching.
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- C7+ paraffin isomerisation process and catalyst therefore
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There is provided a process for selective isomerisation of C4+ paraffins using a catalyst comprising mixed aluminium, tungsten and zirconium oxides, and a hydrogenation/dehydrogenation component, such as palladium or other Group VIII metals. The feed may optionally also include shorter paraffins, aromatics or cycloparaffins.
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- Isomerization of n-Heptane over Pd-Loaded Silico-Alumino-Phosphate Molecular Sieves
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Isomerization of n-heptane was studied on a series of bifunctional SAPO-based catalysts with contents of 0.1 wtpercent Pd.From results on temperature programmed desorption of NH3 it is deduced that the different molecular sieve structures contain nearly identical amounts of silicon substituting for phosphorus in the framework (0.3 to 0.5 silicon atoms per unit cell).Best activities and selectivities for branched heptane isomers are achieved with SAPO-11 and SAPO-31.SAPO-17 and SAPO-5 show substantially lower activities.With SAPO-5, there is a high cracking selectivity which is assumed to be caused by the reduced accessibility of parts of the bridged hydroxyl groups within the molecular sieve framework.Different locations of these acid sites are evidenced by infrared OH vibration spectra recorded after adsorption of n-heptane.
- Parlitz, B.,Schreier, E.,Zubowa, H. -L.,Eckelt, R.,Lieske, E.,et al.
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- Reaction Mechanisms of Isomerization and Cracking of Heptane on Pd/H-Beta Zeolite
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Tha vapor-phase isomerization and cracking of heptane on H-Beta zeolites loaded with various amounts of Pd metal has been studied at a temperature of 505 K and at a total pressure of 0,3 MPa.The cracking of heptane is interpreted as a combination of classic bifunctional hydrocracking and dimerization cracking.The isomerization of heptane proceeds through the classic-bifunctional mechanism and a second mechanism involving dimerization cracking.The contribution of the different mechanisms to the izomerization and cracking is derived from the formation of specific reaction products.The contribution of the different mechanisms is dependent on the Pd content of the zeolite.
- Blomsma, E.,Martens, J. A.,Jacobs, P. A.
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p. 141 - 147
(2007/10/03)
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- On the oxidation of 3-ethylpentane under GifIV and Gif-orsay conditions
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The oxidation of 3-ethylpentane under GifIV (and GoAggII) conditions affords, as major product, 3-acetylpentane and not diethylketone as previously reported. The discrepancy is explained by radical chain autoxidation in presence of a weak tertiary C - H bond.
- Barton, Derek H. R.,Doller, Dario,Ozbalik, Nubar,Balavoine, Gilbert,Gref, Aurore,Boivin, Jean
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p. 353 - 356
(2007/10/02)
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- FUNCTIONALISATION OF SATURATED HYDROCARBONS. Part X. A COMPARATIVE STUDY OF CHEMICAL AND ELECTROCHEMICAL PROCESSES (GIF AND GIF-ORSAY SYSTEMS) IN PYRIDINE, IN ACETONE AND IN PYRIDINE-CO-SOLVENT MIXTURES
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Six saturated hydrocarbons (cyclohexane, 3-ethylpentane, methylcyclopentane, cis- and trans-decalin and adamantane) were oxidised by the Gif system (iron catalyst, oxygen, zinc, carboxylic acid) and its electrochemical equivalent (Gif-Orsay system).Results obtained using various solvents (pyridine, acetone, pyridine-acetone mixtures) were similar for both systems.Total or partial replacement of pyridine with acetone affects the selectivity for secondary positions and lowers the ketone/secondary alcohol ratio.The formation of the same ratio of cis- and trans-decal-9-ol from both cis- and trans-decalin clearly demonstrates that tertiary alcohols result from a mechanism essentially radical in nature.
- Belavoine, Gilbert,Barton, Derek H. R.,Boivin, Jean,Gref, Aurore,Coupanec, Pascale Le,et al.
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p. 1091 - 1106
(2007/10/02)
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- Reactions of organotin hydrides with lithium diisopropylamide and organolithiums. Reactivities of the intermediates and of the lithium hydride produced
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Equimolar lithium diisopropylamide (LDA) and trimethyltin hydride (TMTH) react in tetrahydrofuran (THF) to form diisopropylamine and (trimethylstannyl)lithium, but in diethyl ether or hexanes 2 mol of TMTH is required for complete reaction and the products are diisopropylamine, hexamethylditin, and lithium hydride. When organic halides are present in this reacting system, reduction to alkane or substitution to form the trimethylalkyltin may occur depending on the nature of the halide. These and other observations suggest that (trimethylstannyl)lithium is formed as an intermediate yielding the tetraalkyltin. Studies on the products and stoichiometries of the reductions of alkyl bromides in ether and hexanes suggest that three reducing agents may be involved: TMTH, [Me3Sn(H)N-i-Pr2]-, and [Me3SnSn(H)Me3]-. The latter predominates in ether, and either or both of the others predominate in hexanes. Formation of methylcyclopentane from 1-bromo-5-hexene suggests involvement of a free radical mechanism. When methyllithium is used instead of LDA in the reaction with TMTH, the products are tetramethyltin and lithium hydride. This reaction can also be diverted to reduction by the presence of primary bromides. Aryl bromides react in both systems, but the yields of either substitution or reduction products are low. The lithium hydride formed in these reactions is extremely reactive as a base as shown by a brief study of its reaction with weak carbon acids and amines and as a nucleophile by its reaction with hexamethylditin to form (trimethylstannyl)lithium in THF.
- Reimann, Werner,Kuivila, Henry G.,Farah, Dan,Apoussidis, Theodorus
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p. 557 - 565
(2008/10/08)
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- ALKANE DEHYDROCYCLIZATION AND ALKYLCYCLOPENTANE CONVERSIONS AT 13.8 bar (200 psi) WITH Pt-Al2O3 CATALYSTS
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The selectivity, defined as aromatics/isoalkanes, for the formation of aromatics is greater for the conversion of n-alkanes than for the conversion of alkylcyclopentanes with a platinum nonacidic alumina catalyst.Alkylcyclopentanes undergo hydrogenolysis to isoalkanes with the same carbon number at least ten to twenty times faster than they react to form aromatics over this catalyst.The results do not support an aromatization mechanism that includes the formation of five carbon ring intermediates.
- Hardy, Rita H.,Davis, Burtron H.
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p. 269 - 278
(2007/10/02)
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- Thermolabile Hydrocarbons, XXI. Relationships between Thermal Stability and Strain of Non-Symmetrical Highly Branched Hydrocarbons
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The pyrolysis reaction of 20 hydrocarbons 3 into radicals 4 and tert-butyl radicals was investigated by product analysis and kinetics.It is shown that the same relationships between the free enthalpies of activation and the strain energies observed earlier for the cleavage of symmetrically substituted CC bonds are valid for the cleavage of unsymmetrical substituted bonds.The introduction of the new concept "strain energy of dissociation" (difference in strain between the ground state 3 and the residual strain in the radical fragments 4 and 5) has proven to be particularly useful.It is now possible to predict the rate of homolytic cleavage of almost all simple CC bonds by force field calculations.
- Hellmann, Siegried,Beckhaus, Hans-Dieter,Ruechardt, Christoph
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p. 2238 - 2249
(2007/10/02)
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- CYCLIZATION OF C7-ALKANES OVER Pt BLACK CATALYST
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C6-and C5-cyclization of heptane isomers (and also, olefin formation as a related process) over Pt-black have been studied in pulse and circulation systems.Hydrogendeficient conditions favour aromatization, via presumably terminal olefins.C5-Cyclization in the presence of more hydrogen is accompanied by internal olefin formation.Relative reactivities of all heptane isomers have been measured; this shows that cyclization is easier between terminal methyl groups.Optimum hydrogen pressures for both types of cyclization have been determined (and compared with hydrogenolysis, too).Earlier mechanism suggestion for aromatization and cyclopentane formation have been confirmed; the distinction between two types of bond shift mechanisms producing aromatics (from substituted pentanes) and saturated isomers, respectively, has recieved additional support facilitating the identification of these two reactions with mechanisms proposed in the literature.
- Zimmer, H.,Paal, Z.,Tetenyi, P.
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p. 513 - 532
(2007/10/02)
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- Radical-initiated Reduction of Chloroformates to Alkanes by Tri-n-propylsilane. A Method for Removal of Unwanted Hydroxy-Groups from Organic Molecules
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Chloroformates of primary and secondary alcohols, produced by the reaction of the alcohol with phosgene, are reduced to the corresponding alkane in excellent yields by reaction with tri-n-propylsilane in the presence of t-butyl peroxide at 140 deg C.Unusually large amounts of initiator are required tO)2 per mol of RO*CO*Cl>.The results are rationalized in terms of a free-radical reaction scheme.
- Jackson, Richard A.,Malek, Farideh
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p. 1207 - 1211
(2007/10/02)
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- Estimation of Electron-Transfer Contributions in Reactions of Alkyl Bromides with (Trimethyltin)sodium
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Estimates of the minimum degrees of electron-transfer contributions to the mechanisms of reaction of primary, secondary, and tertiary bromides with (trimethyltin)sodium have been obtained by the use of dicyclohexylphosphine as a free-radical trap.
- Kuivila, Henry G.,Smith, Gary F.
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p. 2918 - 2919
(2007/10/02)
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