115-18-4Relevant articles and documents
Tailoring the framework composition of carbon nitride to improve the catalytic efficiency of the stabilised palladium atoms
Vorobyeva,Chen,Mitchell,Leary,Midgley,Thomas,Hauert,Fako,López,Pérez-Ramírez
, p. 16393 - 16403 (2017)
Graphitic carbon nitride (g-C3N4) exhibits unique properties for the preparation of single-atom heterogeneous catalysts (SAHCs) due to the presence of sixfold nitrogen-based coordination sites in the lattice. Despite the potential to profoundly affect the metal stabilisation and resulting catalytic properties, no work has previously investigated the effect of modifying the carrier composition. Here, we study the impact of doping carbon in g-C3N4 on the interaction with palladium. This is achieved by introducing carbon-rich heterocycles (barbituric acid or 2,4,6-triaminopyrimidine) during the synthesis of bulk and mesoporous g-C3N4. Palladium is subsequently introduced via microwave-irradiation-assisted deposition, which emerges as a highly effective route for the dispersion of single atoms. Detailed characterisation confirms the controlled variation of the C/N ratio of the lattice and reveals the complex interplay with the crystal size, surface area, amount of defects, basic properties and thermal stability of the carrier. Atomic dispersions of palladium with similar surface densities could be obtained on both the stoichiometric and carbon-doped carriers in mesoporous form, but appreciable differences are observed in the ratio of Pd2+/Pd4+. The latter, which provides a measure of the degree of electron transfer from the metal to the carrier, is found to correlate with the activity in the continuous flow semi-hydrogenation of 2-methyl-3-butyn-2-ol. Density functional theory calculations support the decreased adsorption energy of palladium upon doping with carbon and reveal the potentially significant impact of oxygen-containing defects. The findings demonstrate the importance of understanding the metal-carrier interaction to optimise the catalytic efficiency of SAHCs.
Scale up study of capillary microreactors in solvent-free semihydrogenation of 2‐methyl‐3‐butyn‐2‐ol
Cherkasov, Nikolay,Al-Rawashdeh, Ma ’moun,Ibhadon, Alex O.,Rebrov, Evgeny V.
, p. 205 - 212 (2016)
A 2.5 wt.% Pd/ZnO catalytic coating has been deposited onto the inner wall of capillary reactors with a diameter of 0.53 and 1.6 mm. The coatings were characterised by XRD, SEM, TEM and elemental analysis. The performance of catalytic reactors was studied in solvent-free hydrogenation of 2-methyl-3-butyn-2-ol. No mass transfer limitations was observed in the reactor with a diameter of 0.53 mm up to a catalyst loading of 1.0 kg(Pd) m?3. The activity and selectivity of the catalysts has been studied in a batch reactor to develop a kinetic model. The kinetic model was combined with the reactor model to describe the obtained data in a wide range of reaction conditions. The model was applied to calculate the range of reaction conditions to reach a production rate of liquid product of 10–50 kg a day in a single catalytic capillary reactor.
Palladium-bismuth intermetallic and surface-poisoned catalysts for the semi-hydrogenation of 2-methyl-3-butyn-2-ol
Cherkasov, Nikolay,Ibhadon, Alex O.,McCue, Alan J.,Anderson, James A.,Johnston, Shaun K.
, p. 22 - 30 (2015)
The effects of poisoning of Pd catalysts with Bi and annealing in a polyol (ethylene glycol) were studied on the semi-hydrogenation of 2-methyl-3-butyn-2-ol (MBY). An increase in the Pd:Bi ratio from 7 to 1 in the Bi-poisoned catalysts decreased the hydrogenation activity due to blocking of active sites, but increased maximum alkene yield from 91.5% for the Pd catalyst to 94-96% for all Bi-poisoned Pd catalysts, by decreasing the adsorption energy of alkene molecules and suppressing the formation of β-hydride phase. Annealing of the catalysts induced the formation of intermetallic phases and decreased its activity due to sintering of the catalytic particles and low activity of intermetallic compounds. Langmuir-Hinshelwood kinetic modelling of the experimental data showed that poisoning of Pd with Bi changed the relative adsorption constants of organic species suggesting ligand effects at high Bi content.
Solvent-free semihydrogenation of acetylene alcohols in a capillary reactor coated with a Pd-Bi/TiO2 catalyst
Cherkasov, Nikolay,Ibhadon, Alex O.,Rebrov, Evgeny V.
, p. 108 - 115 (2016)
A solvent-free semihydrogenation of 2-methyl-3-butyn-2-ol (MBY) to 2-methyl-3-buten-2-ol was performed in a capillary reactor (10 m long, 0.53 mm i.d.) coated with a titania supported Pd-Bi catalyst. Several coatings with different Pd/Bi ratio have been prepared. The catalysts have been characterized with SEM, TEM, EDX, XRD analysis and N2 adsorption-desorption measurements. The maximum alkene yield of 90% was obtained at a molar Pd/Bi ratio of 11. The yield was increased to 95% in the presence of 10 mol.% pyridine in the reaction mixture. The alkene selectivity decreased with time due to leaching of Bi. The leaching was fully suppressed in the presence of 1 vol.% acetic acid in the reaction mixture. The catalyst remained stable for 100 h of continuous operation. The results demonstrate that capillary reactors provide alkene selectivity the same compared to ideal stirred tank batch reactors.
Structural and functional insights into asymmetric enzymatic dehydration of alkenols
Nestl, Bettina M.,Geinitz, Christopher,Popa, Stephanie,Rizek, Sari,Haselbeck, Robert J.,Stephen, Rosary,Noble, Michael A.,Fischer, Max-Philipp,Ralph, Erik C.,Hau, Hoi Ting,Man, Henry,Omar, Muhiadin,Turkenburg, Johan P,Van Dien, Stephen,Culler, Stephanie J.,Grogan, Gideon,Hauer, Bernhard
, p. 275 - 281 (2017)
The asymmetric dehydration of alcohols is an important process for the direct synthesis of alkenes. We report the structure and substrate specificity of the bifunctional linalool dehydratase isomerase (LinD) from the bacterium Castellaniella defragrans that catalyzes in nature the hydration of β-myrcene to linalool and the subsequent isomerization to geraniol. Enzymatic kinetic resolutions of truncated and elongated aromatic and aliphatic tertiary alcohols (C5-C15) that contain a specific signature motif demonstrate the broad substrate specificity of LinD. The three-dimensional structure of LinD from Castellaniella defragrans revealed a pentamer with active sites at the protomer interfaces. Furthermore, the structure of LinD in complex with the product geraniol provides initial mechanistic insights into this bifunctional enzyme. Site-directed mutagenesis confirmed active site amino acid residues essential for its dehydration and isomerization activity. These structural and mechanistic insights facilitate the development of hydrating catalysts, enriching the toolbox for novel bond-forming biocatalysis.
Novel Fe–Pd/γ-Al2O3 catalysts for the selective hydrogenation of C≡C bonds under mild conditions
Shesterkina, Anastasiya A.,Kozlova, Ludmila M.,Mishin, Igor V.,Tkachenko, Olga P.,Kapustin, Gennady I.,Zakharov, Viktor P.,Vlaskin, Mikhail S.,Zhuk, Andrei Z.,Kirichenko, Olga A.,Kustov, Leonid M.
, p. 339 - 342 (2019)
Novel promising Fe–Pd/γ-Al2O3 catalysts for the selective liquid-phase hydrogenation of unsaturated compounds (phenylacetylene and 2-methylbut-3-yn-2-ol) under ambient conditions have been prepared. They were characterized by low temperature nitrogen adsorption, XRD, SEM, TEM, TPR-H2 and DRIFTS-CO techniques. The presence of Pd–Fe nanoparticles led to increased reactivity and selectivity of the new catalysts in hydrogenation of the C≡C bond to the C=C one as compared to those of the Pd/Al2O3 system.
Efficient synthesis of 3-sulfolenes from allylic alcohols and 1,3-dienes enabled by sodium metabisulfite as a sulfur dioxide equivalent
Dang, Hang T.,Nguyen, Vu T.,Nguyen, Viet D.,Arman, Hadi D.,Larionov, Oleg V.
, p. 3605 - 3609 (2018)
We present herein an efficient and practical method for a gram scale synthesis of 3-sulfolenes using sodium metabisulfite as a safe, inexpensive, and easy to handle sulfur dioxide equivalent. Diversely-substituted 3-sulfolenes can be prepared by reacting a variety of 1,3-dienes or allylic alcohols with sodium metabisulfite in aqueous hexafluoroisopropanol (HFIP) or in aqueous methanol in the presence of potassium hydrogen sulfate. Advantageously, the method enables conversion of allylic alcohols directly to 3-sulfolenes, bypassing intermediate 1,3-dienes.
-
Taylor,Shenk
, p. 2756 (1941)
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Tedeschi et al.
, p. 1118,1120 (1971)
A novel one-pot conversion of allyl alcohols into primary allyl halides mediated by acetyl halide
Kishali, Nurhan,Polat, M. Fatih,Altundas, Ramazan,Kara, Yunus
, p. 67 - 72 (2008)
A new and simple method for the synthesis of the primary allyl chlorides and bromides 9-16 from the secondary or tertiary allyl alcohols 3-8 and acyl halide was developed (Scheme 2, Table 1). Non-commercially available secondary and tertiary allyl alcohols were synthesized from the related ketones and aldehydes via the addition of vinylmagnesium chloride. Mechanistic studies indicate that the alcohols were first acetylated by the acetyl halide and then protonated prior to substitution by the halide, Cl- or Br -, via an 5N2′ reaction, to yield the primary halides (Scheme 5).
Hydrophobic periphery tails of polyphenylenepyridyl dendrons control nanoparticle formation and catalytic properties
Kuchkina, Nina V.,Morgan, David Gene,Kostopoulou, Athanasia,Lappas, Alexandros,Brintakis, Konstantinos,Boris, Bethany S.,Yuzik-Klimova, Ekaterina Yu.,Stein, Barry D.,Svergun, Dmitri I.,Spilotros, Alessandro,Sulman, Mikhaill G.,Nikoshvili, Linda Zh.,Sulman, Esther M.,Shifrina, Zinaida B.,Bronstein, Lyudmila M.
, p. 5654 - 5663 (2014)
(Figure Presented) Here we report control of iron oxide and palladium nanoparticle (NP) formation via stabilization with polyphenylenepyridyl dendrons of the second and third generations with dodecyl periphery. These nanomaterials are developed as magnetically recoverable catalysts. To accurately assess the influence of the dodecyl exterior for the same dendron generation, we also designed a second generation dendron with partial dodecyl periphery. For all dendrons studied, the multicore iron oxide mesocrystals were formed, the sizes and morphology of which were controlled by the dendron generation. Analysis of the static and dynamic magnetic properties, in combination with transmission electron microscopy observations, demonstrate that magnetism is sensitive on the structure-directing capabilities of the type of the dendron which was employed for the mesocrystal stabilization. Close proximity of single cores in such multicore mesocrystals promotes the coupling of the neighboring magnetic moments, thus boosting their magnetization and allowing easy crossover between superparamagnetic and ferrimagnetic behaviors at room temperature. The particularly dramatic role of the dendron structure was also witnessed via the Pd NP formation, which was found to depend on both the dendron generation and its dodecyl periphery. In the case of the catalyst based on the second generation dendron with full dodecyl periphery, no Pd NPs were observed by TEM indicating that these species are of a subnanometer size and are not visible on or near the iron oxide NPs. For the catalyst based on the second generation dendron with partial dodecyl periphery, hydrogen reduction leads to much larger Pd NPs (2.7 nm) due to an unimpeded exchange of Pd species between dendrons and nondense dendron coating with asymmetrical dendrons. The third generation dendron with full dodecyl periphery allows nearly monodisperse 1.2 nm Pd NPs in the shells of iron oxide mesocrystals and the best catalytic properties in selective hydrogenation of dimethylethynylcarbinol. This study suggests a robust approach to control NP formation in magnetically recoverable catalysts for a wide variety of catalytic reactions using dendrons combining rigidity and flexibility in one molecule.
KINETIC RELATIONSHIPS IN FORMATION OF ISOPRENE FROM EQUILIBRIUM MIXTURE OF 3-METHYL-1-BUTEN-3-OL AND 3-METHYL-2-BUTEN-1-OL IN AQUEOUS PERCHLORIC ACID SOLUTIONS
Osipova, G. F.,Ryabova, R. S.,Vinnik, M. I.
, p. 885 - 890 (1982)
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Preparation of semi-hydrogenation catalysts by embedding Pd in layered double hydroxides nanocages via sacrificial template of ZIF-67
Li, Lina,Li, Wenqing,Miao, Shiding,Wang, Jian,Wang, Ziyan,Wei, Cundi,Zhang, Peiping,Zhang, Peng,Zhang, Yan
, (2020)
In this work a Pd/Fe-Co-Ni layered double hydroxide (LDH) composite was prepared and investigated in the semi-hydrogenation of 2-methyl-3-butyn-2-ol (MBY). Hollow nanocages of ternary Fe-Co-Ni LDH were constructed by stacking the LDH nanosheets edge-to-face which inherited the rhombic dodecahedral structure of ZIF-67 templates. Uniform palladium (Pd) nanocrystals with cubic shapes were imbedded in the LDH nanocages via a solvothermal method. The hydroxyl groups on LDH supports were critical to inhibit the association of excess hydrogen atoms on the catalyst, so less MBY molecules were converted to 2-methyl-2-butanol (MBA) during the hydrogenation catalysis. Under optimized reaction conditions the hydrogenation activity of Pd/Fe-Co-Ni LDH was significantly improved, and the conversion of MBY was higher than 99% with selectivity of 2-methyl-3-buten-2-ol (MBE) exceeding 99%. The catalyst was easily recovered and had little reduction in catalytic performance during the cycling reactions.
Capillary microreactor with a catalytic coating based on mesoporous titanium dioxide for the selective hydrogenation of 2-methyl-3-butyn-2-ol
Okhlopkova,Kerzhentsev,Ismagilov
, p. 497 - 503 (2016)
A continuously working capillary microreactor with a catalytic coating based on mesoporous titanium dioxide with embedded Pd nanoparticles was tested in a reaction of the selective hydrogenation of 2-methyl-3-butyn-2-ol (MBI). The catalytic coatings were obtained by the supporting of a carrier sol, which contained colloidal Pd nanoparticles, onto the internal wall of a quartz capillary with a diameter of 250 μm in the dynamic mode. The effects of the concentration of MBI in methanol (0.05–0.2 mol/L), the partial pressure of hydrogen (0.28–1.0 atm), and the reaction temperature (308–333 K) on the catalyst activity and the selectivity of reaction were studied. High selectivity for the formation of the semi-hydrogenated product 2-methyl-3-buten-2-ol was reached at 313 K in an atmosphere of pure hydrogen. At a conversion of 99.9%, the selectivity was 92.3%, which is 15.5% higher than that in a batch reactor. The rate of hydrogenation on the Pd/TiO2 coating was higher by one order of magnitude than that on a commercial Lindlar catalyst. The coating remained stable upon the continuous passage of the flow of a reaction mixture for 500 h.
Freidlin,Gorschkow
, (1960)
Coating the Internal Surface of a Capillary Microreactor for the Selective Hydrogenation of 2-Methyl-3-Butyn-2-ol by PdxZn1 – x/TiO2 Catalysts: A Kinetic Study
Okhlopkova,Kerzhentsev,Ismagilov
, p. 450 - 458 (2018)
The kinetics of the liquid-phase hydrogenation of 2-methyl-3-butyn-2-ol (MBI) on the thin films of Pd50Zn50/TiO2, Pd80Zn20/TiO2, and Pd/TiO2 was studied in a temperature range of 308–333 K at MBI concentrations of 0.1–0.6 mol/L. The films were applied to the internal walls of silica capillaries with an inside diameter of 530 μm. The reaction of MBI hydrogenation at its initial stage was of first order with respect to hydrogen, and the orders of reaction with respect to MBI on Pd50Zn50/TiO2, Pd80Zn20/TiO2, and Pd/TiO2 were 0.3, 0.4, and 0.5, respectively. The yield of the target product 2-methyl-3-buten-2-ol on the bimetallic films was higher than that on Pd/TiO2. The highest yield (94%) was achieved on the film of Pd50Zn50/TiO2 at a conversion of 99%, a temperature of 313 K, and a partial hydrogen pressure of 1 atm. The higher selectivity of the reaction, which occurred according to the Langmuir–Hinshelwood mechanism, on the bimetallic films was explained by a decrease in the alkene/alkyne and alkene/alkane ratios of adsorption constants and by a decrease in the rate constants of 2-methyl-3-buten-2-ol hydrogenation.
Development, Synthesis, and Study of Nanomaterials of Titania Doped by Zirconium for Selective Hydrogenation of 2-Methyl-3-Butyn-2-ol in a Microcapillary Reactor
Okhlopkova,Kerzhentsev,Ismagilov
, p. 474 - 483 (2019)
Abstract: An ordered mesoporous titanium–zirconium TixZr1–xO2 matrix for introducing catalytic nanoparticles was synthesized by self-assembly using titanium isopropoxide and zirconium oxychloride as precursors and amphiphilic triblock copolymer F127 as a template. The process of self-assembly occurs without the addition of an acid to preserve the morphology and structure of the catalytic nanoparticles. When controlling the initial molar ratios of the copolymer to metal precursors, titanium–zirconium nanocomposites with controlled texture and composition were obtained in a wide range of titania content, from 15 to 80 mol % TiO2. The structural and phase properties of the composites were studied by X-ray diffraction, low-temperature nitrogen adsorption, and transmission electron microscopy. Composites have an ordered mesoporous structure, a high specific surface area, a large pore volume, and a uniform pore size distribution. Catalytic coatings of 1 wt % Pd–Zn/TixZr1–xO2 (x = 1.0, 0.8, 0.5) on the inner surface of a capillary reactor were prepared by the dip-coating method using a colloidal solution of Pd–Zn nanoparticles. The developed catalytic coatings based on titanium–zirconium composites exhibit high activity and selectivity (> 96%) in the hydrogenation of 2-methyl-3-butyn-2-ol.
Selective hydrogenation of 2-methyl-3-butyn-2-ol over Pd-nanoparticles stabilized in hypercrosslinked polystyrene: Solvent effect
Nikoshvili, Linda,Shimanskaya, Elena,Bykov, Alexey,Yuranov, Igor,Kiwi-Minsker, Lioubov,Sulman, Esther
, p. 179 - 188 (2015)
Selective hydrogenation of 2-methyl-3-butyn-2-ol (MBY) to 2-methyl-3-butene-2-ol (MBE) over Pd supported on hypercrosslinked polystyrene was studied in polar (ethanol, isopropanol, water) and non-polar (cyclohexane, toluene, octane, hexane, heptane and m-xylene) solvents. The catalytic activity and selectivity were found to be strongly affected by solvent properties such as dipole moment and dielectric constant, but cannot be explained by solvent polarity only. Hydrogen solubility and solvent-catalyst interaction also influential factors. The catalyst activity decreases in the series: alcohols > cyclohexane > water/ethanol mixture > octane ≥ hexane ≥ xylene > toluene > heptane. The highest values of MBE selectivity of 99.6% and 98.7% at 95% MBY conversion were obtained in toluene and in ethanol, respectively.
Reasons for the Inverse Dependence of the Turnover Frequency of Hydrogenation of Unsaturated Compounds on Palladium Catalyst Concentration
Skripov,Belykh,Sterenchuk,Levchenko,Schmidt
, p. 299 - 306 (2021/04/26)
Abstract: The hypotheses about reasons for the inverse dependence of the turnover frequency of hydrogenation of unsaturated compounds (alkyne, alkynol, olefin) on the catalyst concentration were discriminated by kinetic methods combined with electron microscopy. The reasons are: dissociation of polycrystalline Pd–P particles, equilibrium shift (stabilized cluster–cluster + stabilizer), and aggregation–disaggregation of Pd–P particles, the latter being the main reason for the concentration range 0.125–1 mmol/L. The effect of aggregation–disaggregation of Pd–P particles on the catalyst activity differs depending on the substrate. The proposed kinetic model was shown to be consistent with the experimental data for styrene hydrogenation used as an example. The rate constants of some stages were determined.
Generation of Stable Isopentenyl Monophosphate Aryloxy Triester Phosphoramidates as Activators of Vγ9Vδ2 T Cells
Xu, Qin,Taher, Taher E.,Ashby, Elizabeth,Sharif, Maria,Willcox, Benjamin E.,Mehellou, Youcef
, p. 2375 - 2380 (2021/05/26)
Aryloxy triester phosphoramidate prodrugs of the monophosphate derivatives of isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP) were synthesized as lipophilic derivatives that can improve cell uptake. Despite the structural similarity of IPP and DMAPP, it was noted that their phosphoramidate prodrugs exhibited distinct stability profiles in aqueous environments, which we show is due to the position of the allyl bond in the backbones of the IPP and DMAPP monophosphates. As the IPP monophosphate aryloxy triester phosphoramidates showed favorable stability, they were subsequently investigated for their ability to activate Vγ9/Vδ2 T cells and they showed promising activation of this subset of T cells. Together, these findings represent the first report of IPP and DMAPP monophosphate prodrugs and the ability of IPP aryloxy triester phosphoramidate prodrugs to activate Vγ9/Vδ2 T cells highlighting their potential as possible immunotherapeutics.
