Xi:Irritant;
92-52-4Relevant academic research and scientific papers
Towards a zero-waste oxidative coupling of nonactivated aromatics by supported gold nanoparticles
Serna, Pedro,Corma, Avelino
, p. 2136 - 2139 (2014)
We show that gold nanoparticles are able to perform the direct oxidative coupling of nonactivated aromatics with O2 as the only co-reagent. In this reaction, the aromatic acts both as reactant and solvent. Biphenyl, for example, can be obtained from benzene with high selectivity and a turnover number (TON) of 230 per pass. Similarly, several substituted biaryls can be prepared. Pd performs only one TON and even when a second catalytic functionality is introduced, together with strong acidic conditions, TON is always lower than 100. Other catalysts require iodine for performing the reaction, leading to 2 kg of waste for 1 kg of biphenyl formed, whereas no waste is created by the oxidative coupling with gold nanoparticles.
Selective Solid State Photooxidant
Morkin, Tracy L.,Turro, Nicholas J.,Kleinman, Mark H.,Brindle, Cheyenne S.,Kramer, Wolfgang H.,Gould, Ian R.
, p. 14917 - 14924 (2003)
Irradiation of biphenyl encapsulated in the cavities of a NaZSM-5 zeolite framework has been reported to result in the formation of an extremely long-lived radical cation. Here, we show that such zeolite encapsulated radical cations can act as irreversible one-electron oxidants for simple alkenes and dienes, in a solid-state analogue to solution-phase cosensitization. Compared to the well-known semiconductor photooxidizers, such as titanium dioxide, the NaZSM-5 zeolite-based solid photooxidants exhibit enhanced selectivity based on oxidation potential, molecular size and shape, and Lewis base character.
Organonickel chemistry in the catalytic hydrodechlorination of polychlorobiphenyls (PCBs): Ligand steric effects and molecular structure of reaction intermediates
King, Charles M.,Bruce King,Bhattacharyya, Nripendra K.,Gary Newton
, p. 63 - 70 (2000)
Soluble homogeneous organophosphorus - nickel complexes have been used to detoxify polychlorinated biphenyls (PCBs) by catalyzed hydrodechlorination using NaBH2(OCH2CH2OCH3)2 as the hydrogen source. The reactions appear to proceed by NiL3 oxidative addition into C-Cl bonds followed by hydrogenolysis of the metal-carbon bond. In model experiments with decachlorobiphenyl, the cone angle of the organophosphorus ligand L was shown to be a key factor controlling the magnitude and position of chlorine displacement. Hence, ligands leading to para displacement (e.g. (o-MeC6H4O)3P), meta - para displacement (e.g. (EtO)3P and (PhO)3P), and ortho - meta - para displacement (e.g. Me3P and Et3P) were found. Significantly, the highly toxic, coplanar dioxin precursor 3,3′,4,4′-tetrachlorobiphenyl, a meta - para chlorine-substituted congener, was dechlorinated quantitatively with the Et3P catalyst system. Evidence for the presence of organonickel intermediates in the reaction mixtures was obtained by mass spectroscopic and X-ray diffraction studies. Of particular interest is the isolation of square planar complexes p-C6Cl5C6Cl4Ni(PEt3) 2Cl from the reaction of decachlorobiphenyl with NaBH2(OCH2CH2OCH3)2 - (Et3P)2NiCl2 as the catalyst precursor and m-C6Cl5C6Cl4Ni(PEt3) 2Cl from decachlorobiphenyl - Ni(1,5-C8H12)2 - PEt3 at room temperature. All are oxidative addition intermediates and precursors for decachlorobiphenyl hydrodechlorination.
Pd nanoparticle supported reduced graphene oxide and its excellent catalytic activity for the Ullmann C-C coupling reaction in a green solvent
Rana, Surjyakanta,Bidita Varadwaj, G. Bishwa,Jonnalagadda, Sreekantha B.
, p. 13332 - 13335 (2019)
An efficient and easy route to synthesize reduced graphene oxide with well dispersed palladium (Pd) nanoparticles (Pd(0)-RGO) is described. The synthesized materials were fully characterized by different techniques such as: XRD, FTIR, Raman, SEM, and TEM. An average particle size of 7.5 nm for the metal particles was confirmed by TEM analysis. Pd(0)-RGO demonstrated outstanding catalytic activity for Ullmann coupling with 97% yield and good reusability (4 cycles).
Effect of Cu-Promotion on the Performance of Molybdenum Sulfide for Hydrotreating of FCC Gasoline
Betancourt, Paulino,Pinto-Castilla, Susana
, p. 2425 - 2432 (2019)
Abstract: Copper sulfide (either supported or unsupported) has received poor attention as promoter since this chalcogenide displayed modest hydrotreatment activity. In this sense, was evaluated the potential of sulfide CuMo catalyst in the FCC gasoline hydrotreatment. A MoS2 bulk and the industrial NiMo/Al2O3 catalyst were used as reference. According to the results obtained, the NiMo commercial catalyst had higher HDS, HDN, and HYD activity, but with a significant decrease in the octane number (RON). While the CuMo catalysts showed a lower response towards hydrotreatment, maintaining its octane value. According to the results obtained in the characterizations carried out (XRD, XPS, TPR, physisorption of N2, among others), we propose that copper species could be generating geometric and/or electronic changes in the CuMoS phases, increasing the number of active sites. Additionally, the incorporation of the Cu in the crystalline structure could be modifying its electronic structure, granting a metallic character to the active phase. The work demonstrates the potential of CuMo catalyst for HDT of FCC gasoline. Graphical Abstract: [Figure not available: see fulltext.].
Synthesis of NiMo catalysts supported on mesoporous silica FDU-12 with different morphologies and their catalytic performance of DBT HDS
Wang, Xilong,Du, Peng,Chi, Kebin,Duan, Aijun,Xu, Chunming,Zhao, Zhen,Chen, Zhentao,Zhang, Honglei
, p. 146 - 152 (2017)
Mesoporous silica FDU-12 with remarkable morphologies such as hexagonal prisms, spiral rodlike and brick-like, were successfully synthesized under low temperature and strong acidic conditions by introducing of different inorganic salts. The products were characterized by Small-angle X-ray scattering (SAXS) patterns, UV–vis diffuse reflectance Spectroscopy, N2 adsorption-desorption, scanning electron microscopy (SEM), laser Raman spectra (Raman), Fourier transform infrared spectroscopy with pyridine adsorption (pyridine-FTIR), X-ray photoelectron spectrometer (XPS), and transmission electron microscopy (TEM). The results showed that all the samples had high degrees of crystallinity, regular shape, large pore size and specific surface area, while the addition of different inorganic salts had a great influence on the morphology of FDU-12. Furthermore, the DBT HDS performances of FDU-12 supported NiMo hydrodesulfurization (HDS) catalysts were also investigated. The hexagonal prism NiMo/F-HP catalyst had a higher sulfurization degree and more acid sites than other catalysts. The catalytic results indicated that the morphologies and acidities of FDU-12 materials played an essential role in the catalytic performance of DBT HDS over NiMo catalysts. Among the catalysts with different morphologies, the DBT HDS conversions followed the order: hexagonal prism catalyst (NiMo/F-HP)?>?spiral catalyst (NiMo/F-SP)?>?brick-like catalyst (NiMo/F-BL). The highest activity of NiMo/F-HP could be ascribed to the relatively higher acidity, higher sulfurization degree and the better dispersion of the active phases.
Palladium clusters on dicarboxyl-functional hypercrosslinked porous polymers for oxidative homocoupling of benzene with O2
Liu, Yangqing,Zou, Chuanbiao,Wang, Kai,Bian, Zhengyun,Jiang, Shi,Zhou, Yu,Wang, Jun
, (2021)
Aerobic oxidative homocoupling of benzene with dioxygen (O2) is one of the promising routes for the synthesis of important chemical intermediate biphenyl. In the most cases, high valent palladium (Pd) species are regarded as the active sites, while metallic stage Pd° species are inactive. Herein, we presented the fabrication of highly dispersive Pd clusters with the average size of 1.2 nm on a dicarboxylic acid-functional hypercrosslinked polymer (HCP) with large pore volume and high surface area, which was directly synthesized through the copolymerization of phthalic acid and biphenyl via Bronsted acid-catalyzed Friedel-Crafts alkylation. Catalyst behaved excellent catalytic activity in converting benzene into biphenyl via oxidative homocoupling with O2, exhibiting a high yield up to 18 % plus a record turnover number and turnover frequency as larger as 505 and 253 h?1, respectively. Such catalytic behavior is mainly attributed to the formation of ultrafine Pd clusters promoted by the surface dicarboxyl functional groups.
Development of reactive Pd/Fe bimetallic nanotubes for dechlorination reactions
Zahran, Elsayed M.,Bhattacharyya, Dibakar,Bachas, Leonidas G.
, p. 10454 - 10462 (2011)
We described the synthesis and characterization of a new class of bimetallic nanotubes based on Pd/Fe and demonstrated their efficacy in the dechlorination of PCB 77, a polychlorinated biphenyl. One-dimensional iron metal nanotubes of different diameters were prepared by electroless deposition within the pores of PVP-coated polycarbonate membranes using a simple technique under ambient conditions. The longitudinal nucleation of the nanotubes along the pore walls was achieved by mounting the PC membrane between two halves of a U-shape reaction tube. The composition, morphology, and structure of the Pd/Fe nanotubes were characterized by transmission electron microscopy, scanning electron microscopy, inductively coupled plasma-atomic emission spectroscopy, and X-ray powder diffraction spectroscopy. The as-prepared Pd/Fe bimetallic nanotubes were used in dechlorination of 3,3′,4,4′-tetrachlorobiphenyl (PCB 77). In comparison with Pd/Fe nanoparticles, the Pd/Fe nanotubes demonstrated higher efficiency and faster dechlorination of the PCB.
Zeolite-graphene composite as support for molybdenum-based catalysts and their hydrodesulfurization performance
Ali, Islam,Saleh, Tawfik A.
, (2020)
A composite of zeolite Y type -graphene as a support doped with molybdenum-cobalt and molybdenum-nickel (active phase and promoter) was synthesized and evaluated as hydrodesulfurization (HDS) catalysts. The ZGMoCo was found to have the ability to reduce the sulfur content by ≈98 % after a 5 h reaction time which is higher compared to the ZMoCo or ZMoNi. This activity can be ascribed to the improved surface area and better distribution of the active phases (molybdenum and cobalt or nickel) on the zeolite Y type -graphene surface. SEM images showed enhanced dispersion of the active phases on the support surface. As per the BET measurements, the surface area was improved due to the introduction of graphene to be 323.6 m2/g ZGMoCo compared to 257.3 m2/g ZMoCo; and 312.5 m2/g for ZGMoNi compared to 245.7 m2/g for ZMoNi. The work offers a convenient approach to prepare an effective HDS catalyst.
The isomers of [12]annulyne and their reactive relationships to heptalene and biphenyl
Rose, Brad D.,Reiter, Richard C.,Stevenson, Cheryl D.
, p. 8714 - 8718 (2008)
(Chemical Equation Presented) [12]Annulyne not like benzyne: The base-initiated condensation of hexadiyne in nonpolar solvents leads directly to the symmetrical isomers of [12]annulyne, i.e. the all cis isomer, which exists as its cumulene, and the 6,9-tr
