2040-96-2Relevant academic research and scientific papers
Chemistry of Higher Order, Mixed Organocuprates. 5. On the Choice of the Copper(I) Salt for the Formation of R2CuLi
Lipshutz, Bruce H.,Kozlowski, Joseph A.,Wilhelm, Robert S.
, p. 546 - 550 (1983)
Chemical and spectroscopic studies are presented that have been designed to manifest differences in reagent composition and reactivity between mixtures of CuI/2RLi and CuSCN/2RLi.The results indicate that while both Cu(I) salts are reported to serve as precursors to lower order cuprates R2CuLi, CuSCN may actually be forming a higher order, mixed species R2Cu(SCN)Li2.This would explain the discrepancy in coupling reactions of each solution with similar organic substrates under otherwise identical conditions.The presence of added lithium salts demonstrates that while Li I added to CuSCN/2RLi has essentially no effect, introduction of an equivalent of LiSCN to CuI/2RLi dramatically alters the efficiency of ligand transfer.
Improved Hydrodeoxygenation of Phenol to Cyclohexane on NiFe Alloy Catalysts Derived from Phyllosilicates
Han, Qiao,Wang, Hui,Rehman, Mooeez Ur,Shang, Xin,Chen, Haijun,Ji, Na,Tong, Xinli,Shi, Hui,Zhao, Yujun
supporting information, p. 5069 - 5076 (2021/12/14)
A phyllosilicate-derived NiFe/SiO2 catalyst (NiFe/SiO2?AE) was successfully prepared by the ammonia evaporation method and applied in the hydrodeoxygenation of phenol to cyclohexane. Another two catalysts were also prepared for a comparison by impregnation (NiFe/SiO2?IM) and deposition-precipitation (NiFe/SiO2?DP) methods, respectively. It was found that Ni?Fe alloy, the active sites for the hydrogenolysis of C?O bond, can be obtained by the reduction of NiFe2O4 (IM) or phyllosilicate (DP and AE) by H2. The AE strategy can generate more phyllosilicate structure, which improves the dispersion of both Ni?Fe alloy and metallic Ni sites and allows the formation of more interface between these two kinds of sites as well. Therefore, the NiFe/SiO2?AE exhibits a significantly high catalytic performance in the HDO of phenol to cyclohexane. Moreover, the turnover frequency of Ni?Fe alloy sites over NiFe/SiO2?AE catalysts is much higher than those of other two catalysts. It is suggested that the enhanced synergy between the two kinds of active sites in the adsorption of C?O groups and hydrogen molecules ensures the superior intrinsic activity in HDO process.
Accessing Alkyl- and Alkenylcyclopentanes from Cr-Catalyzed Ethylene Oligomerization Using 2-Phosphinophosphinine Ligands
Newland, Robert J.,Smith, Alana,Smith, David M.,Fey, Natalie,Hanton, Martin J.,Mansell, Stephen M.
, p. 1062 - 1073 (2018/03/30)
Desilylation of the 2-phosphinophosphinine 2-PPh2-3-Me-6-SiMe3-PC5H2 with HCl gave 2-PPh2-3-Me-PC5H3, demonstrating the late-stage modification of this bidentate heterocyclic lig
Ring opening of decalin via hydrogenolysis on Ir/- and Pt/silica catalysts
Haas, Andreas,Rabl, Sandra,Ferrari, Marco,Calemma, Vincenzo,Weitkamp, Jens
experimental part, p. 97 - 109 (2012/07/13)
The catalytic conversion of cis-decalin was studied at a hydrogen pressure of 5.2 MPa and temperatures of 250-410 °C on iridium and platinum supported on non-acidic silica. The absence of catalytically active Br?nsted acid sites was indicated by both FT-IR spectroscopy with pyridine as a probe and the selectivities in a catalytic test reaction, viz. the hydroconversion of n-octane. On iridium/silica, decalin hydroconversion starts at ca. 250-300 °C, and no skeletal isomerization occurs. The first step is rather hydrogenolytic opening of one six-membered ring to form the direct ring-opening products butylcyclohexane, 1-methyl-2-propylcyclohexane and 1,2- diethylcyclohexane. These show a consecutive hydrogenolysis, either of an endocyclic carboncarbon bond into open-chain decanes or of an exocyclic carboncarbon bond resulting primarily in methane and C9 naphthenes. The latter can undergo a further endocyclic hydrogenolysis leading to open-chain nonanes. All individual C10 and C9 hydrocarbons predicted by this direct ring-opening mechanism were identified in the products generated on the iridium/silica catalysts. The carbon-number distributions of the hydrocracked products C9- show a peculiar shape resembling a hammock and could be readily predicted by simulation of the direct ring-opening mechanism. Platinum on silica was found to require temperatures around 350-400 °C at which relatively large amounts of tetralin and naphthalene are formed. The most abundant primary products on Pt/silica are spiro[4.5]decane and butylcyclohexane which can be readily accounted for by the well known platinum-induced mechanisms described in the literature for smaller model hydrocarbons, namely the bond-shift isomerization mechanism and hydrogenolysis of a secondary-tertiary carboncarbon bond in decalin.
A mild and efficient rhenium-catalyzed transfer hydrogenation of terminal olefins using alcoholysis of amine-borane adducts as a reducing system
Dong, Hailin,Berke, Heinz
experimental part, p. 1803 - 1808 (2011/06/19)
[ReBr2(NO)(CH3CN)(PTA)2] (PTA = 1, 3, 5-triaza-7-phosphaadamantane) catalyzes the alcoholysis of ammonia-borane and amine-boranes and the catalytic transfer hydrogenations of various terminal olefins. Excellent yields were achieved at 70 °C in isopropanol using tBuOK as a co-catalyst affording TOF values up to 396 h-1.
Hydrodeoxygenation of phenols as lignin models under acid-free conditions with carbon-supported platinum catalysts
Ohta, Hidetoshi,Kobayashi, Hirokazu,Hara, Kenji,Fukuoka, Atsushi
supporting information; experimental part, p. 12209 - 12211 (2011/12/21)
Carbon-supported Pt catalysts are highly active and reusable for the aqueous-phase hydrodeoxygenation of phenols as lignin models without adding any acids. It is suggested that Pt/carbon facilitates the hydrogenation of phenols and the hydrogenolysis of the resulting cyclohexanols. The Royal Society of Chemistry 2011.
Reaction Pathways of 1-Cyclohexyloctane in Admixture with Dodecane on Pt/H-ZSM-22 Zeolite in Three-Phase Hydroconversion
Arroyo, J. A. Munoz,Thybaut, J. W.,Marin, G. B.,Jacobs, P. A.,Martens, J. A.,Baron, G. V.
, p. 29 - 40 (2007/10/03)
Isomerization and hydrocracking of a mixture of 1-cyclohexyloctane and dodecane were performed on Pt/H-ZSM-22 in a three-phase Robinson Mahoney reactor with complete internal mixing (T = 523-543 K, P=7-8 MPa, H2/HC =5). The reaction products from 1-cyclohexyloctane were analyzed in detail and compared with those obtained in the absence of dodecane in a fixed-bed vapor-phase reactor (T = 460 K, P = 0.45 MPa, H2/HC = 450). In the presence of dodecane, the main reaction pathway involved contraction of the six-membered ring to a five-membered ring with concomitant elongation of the octyl chain by one carbon. Subsequently, the nonyl chain underwent methyl branching at carbon positions far from the ring. Methyl branching rearrangements of the cyclohexane ring of 1-cyclohexyloctane were suppressed in the presence of dodecane. In the reaction product fraction of heptylmethylcyclohexanes, all cis-trans and positional isomers were formed except the 1,1'-heptylmethylcyclohexane isomer. The isomer distributions were explained with pore mouth and key-lock catalysis. Pt/H-ZSM-22 did not favor the paring reaction. The distribution of cracked products, and especially the abundant formation of alkylcyclopentanes, was in agreement with cracking through β-scission in the chain rather than by ring dealkylation typical of the paring reaction. Ring opening in 1-cyclohexyloctane and its isomers is a less important side reaction.
Energy Well of Diradicals, VII. - Conjugative-Stabilized Trimethylenemethane Derivatives. Geometry Dependance of the Singlet-Triplet Splitting
Roth, Wolfgang R.,Winzer, Markus,Korell, Michael,Wildt, Holger
, p. 897 - 920 (2007/10/02)
For the three 2,1'-bis-allyl diradicals 3-5 the singlet-triplet splitting has been determined by the oxygen-trapping technique.In agreement with theory the value for the planar diradical is large (>14 kcal*mol-1) whereas for the orthogonal geometry the energy gap is small (6.3 kcal*mol-1).In all cases a triplet groundstate is observed.From the rotational barrier of the exo methylene groups in 6 it is shown that the interconversion of the planar and orthogonal singlet states have activation barriers (6-9 kcal mol-1) which are responsible for their kinetic stability.In contrast to 6, where the formation of the orthogonal diradical proceeds by way of the planar diradical 3, the formation of the analogous orthogonal diradical 29 from homofulvene 17 is a concerted process.This difference is an important observation with respect to the fundamental understanding of concerted and non-concerted reactions. - Key Words: Diradicals / Gas-phase kinetics / Oxygen trapping / Dynamic gas chromatography / Rotational barrier, two-step
Unusual, CO Assisted Cyclo-oligomerization Reactions of Ethylene: Formation of Cyclopentane and Cyclohexane Derivatives by Ytterbium Ziegler-Natta Catalysts
Keim, Wilhelm,Chen, Zhongxin,Shen, Zhiquan
, p. 1923 - 1924 (2007/10/02)
A new oligomerization of ethene to alkylcyclopentanes and/or alkylcyclohexanes using YbCl3/AlEtCl2 or ZrCl4/AlEtCl2 Ziegler-Natta type catalysts is described in which addition of carbon monoxide is essential.
