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Journal articles on the topic 'Metal catalysed'

Author: Grafiati

Published: 4 June 2021

Last updated: 18 May 2024

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1

Rajesh, Nimmakuri, and Dipak Prajapati. "Indium(iii) catalysed regio- and stereoselective hydrothiolation of bromoalkynes." RSC Adv. 4, no. 61 (2014): 32108–12. http://dx.doi.org/10.1039/c4ra04359f.

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Hydrothiolation of bromoalkynes has been reported for the first time under metal catalysed conditions. Indium(iii) trifluoromethanesulfonate was demonstrated as the first catalyst which can catalyse the hydrothiolation of bromoalkynes with absolute regio- and stereoselectivity to generate synthetically valuable (Z)-β-bromo vinyl sulfides in good yields.

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2

Lukey, CA, MA Long, and JL Garnett. "Aromatic Hydrogen Isotope Exchange Reactions Catalyzed by Iridium Complexes in Aqueous Solution." Australian Journal of Chemistry 48, no. 1 (1995): 79. http://dx.doi.org/10.1071/ch9950079.

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Sodium hexachloroiridate (III) and sodium hexachloroiridate (IV) have been used as homogeneous catalysts for hydrogen isotope exchange between benzenoid compounds and water. The ideal solvent consisted of 50 mole % acetic acid/water, and the optimum temperature was found to be 160°C. Under these conditions the rate of incorporation of deuterium into benzene was significant (typically 15% D in 6 h), and reduction to iridium metal was minimized. The active catalytic species was identified as a solvated iridium(III) species, which is also postulated to be the active catalyst in solutions containing hexachloroiridate (IV). The kinetics of exchange in benzene catalysed by sodium hexachloroiridate (III) were elucidated, and found to be more complex than for the corresponding sodium tetrachloroplatinate (II) catalysed exchange, in that a two-term rate dependence was found for catalyst concentration and the reaction was inversely dependent on hydrogen ion concentration. The reaction was found to be independent of chloride ion concentration, this confirming that the active catalyst is a solvated species. Isotopic labelling in all compounds was confined to the aromatic ring, and most substituted benzenes exhibited deactivation of the ortho positions, indicating that a dissociative π-complex exchange mechanism was operating. This was confirmed by exchange into naphthalene, where it was found that labelling was predominantly in the β position. Facile exchange into nitrobenzene provided good evidence of homogeneous catalysis, and not catalysis by precipitated metal.

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3

Wang, Jian, and Yi Fan Zhang. "The Study of Divalent Metal Ion Catalysts on Phenol-Formaldehyde Resol Resins." Applied Mechanics and Materials 71-78 (July 2011): 818–21. http://dx.doi.org/10.4028/www.scientific.net/amm.71-78.818.

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The curing characteristic of phenol-formaldehyde resol resins catalyzed with magnesium hydroxide, calcium hydroxide and barium hydroxide was studied in this study.The effects of catalysts on chemical structure of phenol formaldehyde resin was investigated by fourier transform infrared.The results indicated that divalent metal ions catalysts played an important role influence both the cure rate and cure time.Phenol formaldehyde resin catalysed by diffierent catalysts showed diffierent addition of formaldehyde onto ortho positions of phenolic rings.The order of the divalent metal ions effectiveness studied in alkaline conditions is calcium hydroxide, barium hydroxide and magnesium hydroxide.

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4

Nyembe, Sanele, Gebhu Ndlovu, Poslet Shumbula, Richard Harris, Nosipho Moloto, and Lucky Sikhwivhilu. "Laser Assisted Catalytic Growth of Silicon Nanowires Using Gold and Nickel Catalysts." Journal of Nanoscience and Nanotechnology 21, no. 10 (October 1, 2021): 5260–65. http://dx.doi.org/10.1166/jnn.2021.19448.

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Laser assisted synthesis of silicon nanowires (SiNWs) was successfully achieved through the use of gold and nickel as catalysts. The diameter of the resulting SiNWs was found to be dependent on that of the catalyst in the case of gold catalyst. The gold catalysed silicon nanowires were unevenly curved and branched owing to the high kinetic energy possessed by gold nanoparticles (AuNPs) at relatively high processing temperature. The use of nickel as catalyst resulted in the formation of several SiNWs on a single nickel catalyst crystallite due to interconnection of the nickel metal crystallites at processing temperature. The morphology of SiNWs catalysed by both nickel and gold was controlled by optimising the laser energy during ablation.

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5

Ceder, Rosa Ma, Arnald Grabulosa, Guillermo Muller, and Mercè Rocamora. "Metal catalysed hydrovinylation." Catalysis Science & Technology 3, no. 6 (2013): 1446. http://dx.doi.org/10.1039/c3cy00084b.

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6

Li, Suan, Zhenguang Sun, Qi Liu, Hang Ye, and Kunpeng Wang. "Self-catalysed hydrogenation of heavy oil and coal mixtures." Polish Journal of Chemical Technology 25, no. 2 (June 1, 2023): 8–14. http://dx.doi.org/10.2478/pjct-2023-0011.

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Abstract Coal liquefaction and heavy oil processing have become the urgent need for national energy strategic technology reserves in China. However, the inactivation of solid catalysts in these processes is an inevitable problem. Therefore, a self-catalysed method was proposed. The properties of raw oil could be changed by adding a modifier, as it has the function of self-catalysis, and the additional catalyst is no longer needed. The effect of 200 ppm modifier on the hydrogenation of heavy oil and 500 ppm on the hydrogenation of coal and oil were investigated. The results showed that modifiers could be miscible with heavy oil at 50~100 °C and could change the properties of oil. When the temperature exceeded 250 °C, the sulfur element in the heavy oil combined with the metal element brought in by the modifier to form a particle with the size of 2–8 nm, which could interact with the hydrogen molecule to activate the hydrogen molecule. Activated hydrogen atoms further formed the complexes with nickel, vanadium, calcium, iron, and other elements in heavy oil to achieve the purpose of purifying and lightening the oil phase. Therefore, the self-catalysed method could be widely used in oil refining and would greatly promote the development of the oil refining and catalysis industry.

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7

Saha, Debasree, and Chhanda Mukhopadhyay. "Metal Nanoparticles: An Efficient Tool for Heterocycles Synthesis and Their Functionalization via C-H Activation." Current Organocatalysis 6, no. 2 (June 24, 2019): 79–91. http://dx.doi.org/10.2174/2213337206666181226152743.

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Background: Metal nanoparticles have been extensively used in the synthesis of organic molecules during the last few decades especially due to their high catalytic activity. Organic reactions involving C-H functionalisations are very much in demand as they provide a direct method of derivatisation of organic molecules, thus making the process economical. In the recent years, metal nanoparticles catalysed C-H activation reactions have led to the design of useful molecules especially heterocyclic motifs which form the core structure of drugs and thus have high biological and industrial importance. Methods: In this review, we present a collection of reactions where metal nanoparticles are instrumental in the synthesis and functionalization of heterocycles via C-H activation. The review consists of three units namely, Nano-copper catalysed C-H activation reactions, nano-palladium catalysed CH activation reactions and other nano-metals catalysed C-H activation reactions. Results: The discussion reflects the scope of nano-metals as effective catalysts for the synthesis and functionalization of heterocycles as well as the efficiency of nano-metals towards catalysing economic and environmentally viable reaction protocols. Conclusion: The theme of this review is to correlate nanometal catalysis, heterocyclic synthesis and C-H activation, each of which in itself forms an integral part of modern day chemical research. Thus, the review will hopefully highlight the need for future development and research in this area and be instrumental in guiding researchers towards fulfilling that goal.

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8

Guangqing, Zhang, Shenjun Qin, Li Zhen, Han Haiyan, Li Hui, and Tao Chang. "Coupling reaction of epoxide and carbon dioxide catalysed by alkali metal salts in the presence of ß-cyclodextrin derivatives." World Journal of Engineering 14, no. 2 (April 10, 2017): 159–64. http://dx.doi.org/10.1108/wje-12-2016-0172.

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Purpose This study aims to investigate the coupling reaction of epoxide and CO2 catalysed by alkali metal salts in the presence of ß-cyclodextrin (ß-CD) derivatives to generate cyclic carbonates at various conditions. Design/methodology/approach The coupling reaction was catalysed by alkali metal salts. The effects of the co-catalysts were investigated by using the conversion rate of raw materials. The affecting factors, such as reaction temperature, amount of the co-catalyst and reaction time, were explored. The possible mechanism of the coupling reaction was discussed. Findings Results showed that the structure of ß-CD is an important factor influencing the catalytic activity for the coupling reaction of epoxide with CO2. The catalytic system of 2,3,6-trimethyl-ß-CD with potassium iodide (KI) showed a high catalytic activity. The protocol was expanded to various epoxides, which provided the corresponding cyclic carbonates in excellent yields. The apparent decrease in the yields was not detected after four recycling times. Moreover, the mechanism for the synergetic effect of the catalyst was proposed. Originality/value The coupling reactions were achieved in the presence of different structure of ß-CD as co-catalysts. The affecting of substituent of ß-CD were investigated.

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9

Ralser, Markus. "The RNA world and the origin of metabolic enzymes." Biochemical Society Transactions 42, no. 4 (August 1, 2014): 985–88. http://dx.doi.org/10.1042/bst20140132.

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An RNA world has been placed centre stage for explaining the origin of life. Indeed, RNA is the most plausible molecule able to form both a (self)-replicator and to inherit information, necessities for initiating genetics. However, in parallel with self-replication, the proto-organism had to obtain the ability to catalyse supply of its chemical constituents, including the ribonucleotide metabolites required to replicate RNA. Although the possibility of an RNA-catalysed metabolic network has been considered, it is to be questioned whether RNA molecules, at least on their own, possess the required catalytic capacities. An alternative scenario for the origin of metabolism involves chemical reactions that are based on environmental catalysts. Recently, we described a non-enzymatic glycolysis and pentose phosphate pathway-like reactions catalysed by metal ions [mainly Fe(II)] and phosphate, simple inorganic molecules abundantly found in Archaean sediments. While the RNA world can serve to explain the origin of genetics, the origin of the metabolic network might thus date back to constraints of environmental chemistry. Interestingly, considering a metal-catalysed origin of metabolism gives rise to an attractive hypothesis about how the first enzymes could have formed: simple RNA or (poly)peptide molecules could have bound the metal ions, and thus increased their solubility, concentration and accessibility. In a second step, this would have allowed substrate specificity to evolve.

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10

Badarau, Adriana, Christian Damblon, and Michael I. Page. "The activity of the dinuclear cobalt-β-lactamase from Bacillus cereus in catalysing the hydrolysis of β-lactams." Biochemical Journal 401, no. 1 (December 11, 2006): 197–203. http://dx.doi.org/10.1042/bj20061002.

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Metallo-β-lactamases are native zinc enzymes that catalyse the hydrolysis of β-lactam antibiotics, but are also able to function with cobalt(II) and require one or two metal-ions for catalytic activity. The hydrolysis of cefoxitin, cephaloridine and benzylpenicillin catalysed by CoBcII (cobalt-substituted β-lactamase from Bacillus cereus) has been studied at different pHs and metal-ion concentrations. An enzyme group of pKa 6.52±0.1 is found to be required in its deprotonated form for metal-ion binding and catalysis. The species that results from the loss of one cobalt ion from the enzyme has no significant catalytic activity and is thought to be the mononuclear CoBcII. It appears that dinuclear CoBcII is the active form of the enzyme necessary for turnover, while the mononuclear CoBcII is only involved in substrate binding. The cobalt-substituted enzyme is a more efficient catalyst than the native enzyme for the hydrolysis of some β-lactam antibiotics suggesting that the role of the metal-ion is predominantly to provide the nucleophilic hydroxide, rather than to act as a Lewis acid to polarize the carbonyl group and stabilize the oxyanion tetrahedral intermediate.

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11

Alonso, José Miguel, María Teresa Quirós, and María Paz Muñoz. "Chirality transfer in metal-catalysed intermolecular addition reactions involving allenes." Organic Chemistry Frontiers 3, no. 9 (2016): 1186–204. http://dx.doi.org/10.1039/c6qo00207b.

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12

Shul’pin, Georgiy B. "Metal-catalysed hydrocarbon oxidations." Comptes Rendus Chimie 6, no. 2 (February 2003): 163–78. http://dx.doi.org/10.1016/s1631-0748(03)00021-3.

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13

Becica, Joseph, and Graham E. Dobereiner. "The roles of Lewis acidic additives in organotransition metal catalysis." Organic & Biomolecular Chemistry 17, no. 8 (2019): 2055–69. http://dx.doi.org/10.1039/c8ob02856g.

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We present recent advances in prominent organotransition metal-catalysed reactions in which Lewis acid cocatalysts are employed to increase catalyst activity or selectivity. The roles of Lewis acids are discussed.

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14

Yuan, Jia, Ying Zhang, Hong Yu, Cuiying Wang, Sixuan Meng, Jian Chen, Guang-Ao Yu, and Chi-Ming Che. "Transition metal complexes with functionalized indenyl phosphine ligands: structures and catalytic properties." Organic & Biomolecular Chemistry 20, no. 3 (2022): 485–97. http://dx.doi.org/10.1039/d1ob01884a.

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This review summarizes the recent development of the use and impact of indenyl phosphines in the coordination chemistry and transition-metal-catalysed transformations, especially in E–H (E = H, C, Si and B) bonds activation, and palladium-catalyzed cross-coupling reactions.

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15

Roy, Lisa, Bhaskar Mondal, and Shengfa Ye. "Computational mechanistic insights into non-noble-metal-catalysed CO2 conversion." Dalton Transactions 49, no. 46 (2020): 16608–16. http://dx.doi.org/10.1039/d0dt03096a.

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16

Mohamed, Ziyaad, Venkata D. B. C. Dasireddy, Sooboo Singh, and Holger B. Friedrich. "The Mitigation of CO Present in the Water–Gas Shift Reformate Gas over IR-TiO2 and IR-ZrO2 Catalysts." Catalysts 11, no. 11 (November 15, 2021): 1378. http://dx.doi.org/10.3390/catal11111378.

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CO hydrogenation and oxidation were conducted over Ir supported on TiO2 and ZrO2 catalysts using a feed mimicking the water–gas shift reformate stream. The influence of the support interaction with Ir and the catalysts’ redox and CO chemisorption properties on activity and selectivity were evaluated. Both catalysts oxidised CO to CO2 in the absence of H2, and a conversion of 70% was obtained at 200 °C. For the CO oxidation in the presence of H2 over these catalysts, the oxidation of H2 was favoured over CO due to H2 spillover occurring at the active metal and support interface, resulting in the formation of interstitials catalysed by Ir. However, both catalysts showed promising activity for CO hydrogenation. Ir-ZrO2 was more active, giving 99.9% CO conversions from 350 to 370 °C, with high selectivity towards CH4 using minimal H2 from the feed. Furthermore, results for the Ir-ZrO2 catalyst showed that the superior activity compared to the Ir-TiO2 catalyst was mainly due to the reducibility of the support and its interaction with the active metal. Controlling the isoelectric point during the synthesis allowed for a stronger interaction between Ir and the ZrO2 support, which resulted in higher catalytic activity due to better metal dispersions, and higher CO chemisorption capacities than obtained for the Ir-TiO2 catalyst.

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17

Verma, Piyush Kumar, Mahadev L. Shegavi, Shubhankar Kumar Bose, and K. Geetharani. "A nano-catalytic approach for C–B bond formation reactions." Organic & Biomolecular Chemistry 16, no. 6 (2018): 857–73. http://dx.doi.org/10.1039/c7ob02958f.

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Nanoparticle-catalysed borylation is one of the most convenient methods for the synthesis of organoboranes to overcome the confines of homogeneous catalysis such as recyclability and heavy metal contamination.

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18

Vayenas, C. G., S. Bebelis, I. V. Yentekakis, P. Tsiakaras, and H. Karasali. "Non-Faradaic Electrochemical Modification of Catalytic Activity." Platinum Metals Review 34, no. 3 (July 1, 1990): 122–30. http://dx.doi.org/10.1595/003214090x343122130.

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The catalytic activity and selectivity of platinum metals can be altered dramatically and reversibly by interfacing the metal with a solid electrolyte which supplies ions onto the catalyst surface under the influence of an external potential. The induced change in catalytic rate is orders of magnitude higher than the rate of ion supply. This new effect has revealed a surprisingly simple exponential relationship between catalytic activity and catalyst work function. The effect appears to apply to all heterogeneously catalysed reactions, but is particularly pronounced for platinum. This interfacing of electrochemistry and catalysis appears to offer some exciting theoretical and technological possibilities.

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19

Telalović, Selvedin, and Ulf Hanefeld. "Investigation of the cyanosilylation catalysed by metal-siliceous catalysts." Catalysis Communications 12, no. 6 (February 2011): 493–96. http://dx.doi.org/10.1016/j.catcom.2010.11.012.

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20

Sánchez-Bayo, Alejandra, Rosalía Rodríguez, Victoria Morales, Nima Nasirian, Luis Fernando Bautista, and Gemma Vicente. "Hydrothermal Liquefaction of Microalga Using Metal Oxide Catalyst." Processes 8, no. 1 (December 20, 2019): 15. http://dx.doi.org/10.3390/pr8010015.

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The yield and composition of the biocrude obtained by hydrothermal liquefaction (HTL) of Nannocloropsis gaditana using heterogeneous catalysts were evaluated. The catalysts were based on metal oxides (CaO, CeO2, La2O3, MnO2, and Al2O3). The reactions were performed in a batch autoclave reactor at 320 °C for 10 min with a 1:10 (wt/wt) microalga:water ratio. These catalysts increased the yield of the liquefaction phase (from 94.14 ± 0.30 wt% for La2O3 to 99.49 ± 0.11 wt% for MnO2) as compared with the thermal reaction (92.60 ± 1.20 wt%). Consequently, the biocrude yields also raised in the metal oxides catalysed HTL, showing values remarkably higher for the CaO (49.73 ± 0.9 wt%) in comparison to the HTL without catalyst (42.60 ± 0.70 wt%). The N and O content of the biocrude obtained from non-catalytic HTL were 6.11 ± 0.02 wt% and 10.50 ± 0.50 wt%, respectively. In this sense, the use of the metal oxides decreased the N content of the biocrude (4.62 ± 0.15–5.45 ± 0.11 wt%), although, they kept constant or increased its O content (11.39 ± 2.06–21.68 ± 0.03 wt%). This study shows that CaO, CeO2 and Al2O3 can be promising catalysts based on the remarkable amount of biocrude, the highest values of C, H, heating value, energy recovery, and the lowest content of N, O and S.

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21

Zhao, Siling, and Neal P. Mankad. "Metal-catalysed radical carbonylation reactions." Catalysis Science & Technology 9, no. 14 (2019): 3603–13. http://dx.doi.org/10.1039/c9cy00938h.

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22

Moinet, Claude, Jean-Pierre Hurvois, and Anny Jutand. "Organic and Metal-Catalysed Electrosynthesis." Advances in Organic Synthesis 1, no. 1 (March 1, 2005): 403–53. http://dx.doi.org/10.2174/1574087054582978.

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23

Cardona, Francesca, and Andrea Goti. "Metal-catalysed 1,2-diamination reactions." Nature Chemistry 1, no. 4 (June 22, 2009): 269–75. http://dx.doi.org/10.1038/nchem.256.

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24

Cunningham, R. H., A. V. G. Mangnus, J. van Grondelle, and R. A. van Santen. "Metal catalysed alkylation of alkenes." Catalysis Today 21, no. 2-3 (December 1994): 431–39. http://dx.doi.org/10.1016/0920-5861(94)80165-7.

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25

Fairley, Michael, Laia Davin, Alberto Hernán-Gómez, Joaquín García-Álvarez, Charles T. O'Hara, and Eva Hevia. "s-Block cooperative catalysis: alkali metal magnesiate-catalysed cyclisation of alkynols." Chemical Science 10, no. 22 (2019): 5821–31. http://dx.doi.org/10.1039/c9sc01598a.

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26

Banerjee, Rupendranath. "Metal-ion catalysed aquation of transition metal complexes." Coordination Chemistry Reviews 68 (December 1985): 145–67. http://dx.doi.org/10.1016/0010-8545(85)80033-3.

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27

Thomas, Stephen P., and Jingying Peng. "Activation Strategies for Earth-Abundant Metal Catalysis." Synlett 31, no. 12 (April 6, 2020): 1140–46. http://dx.doi.org/10.1055/s-0039-1690873.

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The use of earth-abundant metal-catalysed organic transformations has increased significantly in recent years. Where low-oxidation-state catalysts are required, the in situ activation of metal(II/III) salts offers an operationally simple method to access these catalysts. Here we present the development of activation strategies from the use of reducing organometallic reagents to endogenous activation. Applications in alkene and alkyne hydrofunctionalisation reactions will be used to highlight the synthetic applications of the activation methods discussed.1 Introduction2 In situ Activation Using Organometallic Reagents3 In situ Activation Using Nonorganometallic Reagents4 ‘Activator-Free’ Systems5 Conclusions

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28

Kumar, Mithilesh, Kamini Singh, and R. A. Singh. "Aspects of thermodynamic parameters with a kinetic approach of transition metal catalysed by potassium bromate oxidation of methyl diethylene glycol (MDG) in alkaline medium." Research Journal of Chemistry and Environment 26, no. 9 (August 25, 2022): 7–11. http://dx.doi.org/10.25303/2609rjce07011.

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The kinetic data obtained in ruthenium(VI) catalysed oxidation of methyldiethylene glycol (MDG) in alkaline medium using potassium bromate as oxidant and transition metal ruthenium tetroxide as a homogenous catalyst. In this kinetic reaction, Hg(OAc)2 acts as a liberated bromide ion scavenger. The result shows first order with respect to KBrO3, methyldiethylene glycol (MDG) and transition metal respectively. It shows zero order dependences of the reaction on aqueous sodium hydroxide, which is used as medium of the reaction and also zero effect of mercuric acetate. In this catalysed reaction, ionic strength has positive effect. The corresponding acid was found to be main oxidation product. A plausible reaction mechanism in agreement with kinetic results was put forward.

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29

Dragutan, V., I. Dragutan, and A. T. Balaban. "Metathesis Catalysed by the Platinum Group Metals." Platinum Metals Review 44, no. 2 (April 1, 2000): 58–66. http://dx.doi.org/10.1595/003214000x4425866.

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Metathesis (from the Greek meta tithemi = change place) describes in chemistry the interchange of atoms between two molecules. The metathesis of olefins is the formal scission of a pair of double bonds, followed by the interchange of their carbon atoms. Metathesis polymerisation of cycloolefins refers to the apparent ring cleavage at the double bond, accompanied by polymerisation to unsaturated polymers (la, lb). Nowadays metathesis is established as a powerful method of synthesis in organic and polymer chemistry (), and platinum group metal catalysts have played a prominent role in this achievement. Metathesis has resulted in both unique syntheses and novel compounds. In this review metathesis reactions catalysed by platinum group metals are described, specifically the types of catalyst, their metathesis activity and various ring-opening and ring-closing reactions. Part II of this paper will be published in the July issue of this Journal.

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30

SOLANO, Francisco, Celia JIMÉNEZ-CERVANTES, José H. MARTÍNEZ-LIARTE, José C. GARCÍA-BORRÓN, José R. JARA, and José A. LOZANO. "Molecular mechanism for catalysis by a new zinc-enzyme, dopachrome tautomerase." Biochemical Journal 313, no. 2 (January 15, 1996): 447–53. http://dx.doi.org/10.1042/bj3130447.

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Dopachrome tautomerase (DCT; EC 5.3.3.12) catalyses the conversion of L-dopachrome into 5,6-dihydroxyindole-2-carboxylic acid in the mammalian eumelanogenic biosynthetic pathway. This enzyme, also named TRP2, belongs to a family of three metalloenzymes termed the tyrosinase-related proteins (TRPs). It is well known that tyrosinase has copper in its active site. However, the nature of the metal ion in the active site of DCT is under discussion. Whereas theoretical predictions based on similarity between the protein sequences of the TRPs suggest the presence of copper, the different inhibition pattern of DCT with some metal chelators compared with that of tyrosinase suggests that the nature of the metal ion could differ. Direct estimations of the metal content in purified DCT preparations show the presence of around 1.5 Zn atoms/molecule and the absence of copper. Apoenzyme preparation by treatment of DCT with cyanide or o-phenanthroline followed by reconstitution experiments of tautomerase activity in the presence of different ions confirmed that the metal cofactor for the DCT active site is zinc. Our results are consistent with Zn2+ chelation by the highly conserved histidine residues homologous to the histidines at the classical copper-binding sites in tyrosinase. This finding accounts for the reaction catalysed by DCT, i.e. a tautomerization, versus the copper-mediated oxidations catalysed by tyrosinase. Based on the predicted tetrahedrical co-ordination of the zinc ions in the enzyme active site, a molecular mechanism for the catalysis of L-dopachrome tautomerization is proposed. From the present data, the existence of additional ligands for metal ions other than zinc in the DCT molecule, such as the proposed cysteine iron-binding sites, cannot be completely ruled out. However, if such sites exist, they could be subsidiary binding sites, whose function would be likely to stabilize the protein.

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31

Myers, T. W., and L. A. Berben. "Aluminium–ligand cooperation promotes selective dehydrogenation of formic acid to H2 and CO2." Chem. Sci. 5, no. 7 (2014): 2771–77. http://dx.doi.org/10.1039/c4sc01035c.

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Selective conversion of formic acid to H₂ and CO₂ is catalysed by a molecular aluminum complex. Metal–ligand cooperative interactions stabilize a transition state for an outer-sphere β-hydride abstraction mechanism for catalysis.

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32

Harris, Peter J. F. "The surface structure of platinum catalyst particles." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 4 (August 1990): 296–97. http://dx.doi.org/10.1017/s0424820100174618.

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For many metal-catalysed reactions, activity and selectivity depend strongly on the structure of the metal surface. However, surprisingly little is known about the surface structures of supported ultrafine metal particles of the type used in practical catalysts. Transmission electron microscopy can play an important role in this area, and is beginning to produce results which could have a major impact on our understanding of processes such as catalyst poisoning and promotion.In this study, which builds on previous work, the effect of various heat-treatments on the shapes and surface structures of alumina-supported platinum particles has been investigated using both conventional bright field TEM and high-resolution imaging. It has been found, for example, that heating in hydrogen tends to produce almost spherical particles with little faceting, as shown in Figure 1. Heating in sulphur-containing atmospheres, on the other hand, produces sharp (100) faceting so that the particles often display square or rectangular profiles, as shown in Figure 2. It is well known that sulphur poisoning can produce changes in catalytic selectivity without deactivating the catalyst completely.

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33

Thomas, Stephen, Nate Ang, Cornelia Buettner, Scott Docherty, Alessandro Bismuto, Jonathan Carney, Jamie Docherty, and Michael Cowley. "Borane-Catalysed Hydroboration of Alkynes and Alkenes." Synthesis 50, no. 04 (November 20, 2017): 803–8. http://dx.doi.org/10.1055/s-0036-1591719.

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Simple, commercially available borane adducts, H3B·THF and H3B·SMe2, have been used to catalyse the hydroboration of alkynes and alkenes with pinacolborane to give the alkenyl and alkyl boronic esters, respectively. Alkynes and terminal alkenes underwent highly regioselective hydroboration to give the linear boronic ester products. Good functional group tolerance was observed for substrates bearing ester, amine, ether and halide substituents. This catalytic process shows comparable reactivity to transition-metal-catalysed hydroboration protocols.

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34

Steven, Alan. "Micelle-Mediated Chemistry in Water for the Synthesis of Drug Candidates." Synthesis 51, no. 13 (May 21, 2019): 2632–47. http://dx.doi.org/10.1055/s-0037-1610714.

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Micellar reaction conditions, in a predominantly aqueous medium, have been developed for transformations commonly used by synthetic chemists working in the pharmaceutical industry to discover and develop drug candidates. The reactions covered in this review are the Suzuki–Miyaura, Miyaura borylation, Sonogashira coupling, transition-metal-catalysed CAr–N coupling, SNAr, amidation, and nitro reduction. Pharmaceutically relevant examples of these applications will be used to show how micellar conditions can offer advantages in yield, operational ease, amount of waste generated, transition-metal catalyst loading, and safety over the use of organic solvents, irrespective of the setting in which they are used.1 Introduction2 Micelles as Solubilising Agents3 Micelles as Nanoreactors4 Designer Surfactants5 A Critical Evaluation of the Case for Chemistry in Micelles6 Scope of Review7 Suzuki–Miyaura Coupling8 Miyaura Borylation9 Sonogashira Coupling10 Transition-Metal-Catalysed CAr–N Couplings11 SNAr12 Amidation13 Nitro Reduction14 Micellar Sequences15 Summary and Outlook

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35

Brunner, Henri, Henri B. Kagan, and Georg Kreutzer. "Asymmetric catalysis. Part 153: Metal-catalysed enantioselective α-ketol rearrangement." Tetrahedron: Asymmetry 14, no. 15 (August 2003): 2177–87. http://dx.doi.org/10.1016/s0957-4166(03)00433-6.

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de Campo, Floryan, Dominique Lastécouères, and Jean-Baptiste Verlhac. "New and improved catalysts for transition metal catalysed radical reactions." Chemical Communications, no. 19 (1998): 2117–18. http://dx.doi.org/10.1039/a804915g.

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37

Scamp, Ryan J., Bradley Scheffer, and Jennifer M. Schomaker. "Regioselective differentiation of vicinal methylene C–H bonds enabled by silver-catalysed nitrene transfer." Chemical Communications 55, no. 51 (2019): 7362–65. http://dx.doi.org/10.1039/c9cc04006d.

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38

Li, Yahui, Yuya Hu, and Xiao-Feng Wu. "Non-noble metal-catalysed carbonylative transformations." Chemical Society Reviews 47, no. 1 (2018): 172–94. http://dx.doi.org/10.1039/c7cs00529f.

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39

Jiang, Guanyu, Xinduo Sun, Fanrui Zhou, Kun Liang, and Qian Chen. "Chiral Quaternary Ammoniums Derived from Dehydroabietylamine: Synthesis and Application to Alkynylation of Isatin Derivatives Catalyzed by Silver." Catalysts 11, no. 12 (December 3, 2021): 1479. http://dx.doi.org/10.3390/catal11121479.

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Abietic acid and its derivatives have broadly been used in fine chemicals and are renewable resources. Its inherent chiral rigid tricyclic phenanthrene skeleton is unique. Its utilities in asymmetric catalysis remain to be explored. A series new amide-type chiral quaternary ammoniums bearing dehydroabietylamine were designed, and prepared by two convenient steps. Acylation of dehydroabietylamine with bromoacetyl chloride afforded amide holding bromoacetyl group in higher yields using triethyl amine as base. Subsequent quaternization reaction gave the desired amide-type chiral quaternary ammoniums. The new chiral quaternary ammoniums can be used as phase-transfer catalyst (PTC) for the transition metal-catalysed alkynylation of isatin derivatives.

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Beletskaya, Irina, and Andrew Pelter. "Hydroborations catalysed by transition metal complexes." Tetrahedron 53, no. 14 (April 1997): 4957–5026. http://dx.doi.org/10.1016/s0040-4020(97)00001-x.

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41

Abraham, K. M., M. Alamgir, E. B. Willstaedt, and W. P. Kilroy. "Metal phthalocyanine-catalysed Li/SOCl2 cells." Electrochimica Acta 37, no. 3 (March 1992): 531–43. http://dx.doi.org/10.1016/0013-4686(92)87046-3.

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Cameron, Thomas M., R. Tom Baker, and Stephen A. Westcott. "Metal-catalysed multiple boration of ketimines†." Chemical Communications, no. 21 (1998): 2395–96. http://dx.doi.org/10.1039/a805792c.

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43

Ventura-Espinosa, David, and Jose A. Mata. "Multiple-Metal (De-)Hydrogenation-Catalysed Processes." European Journal of Inorganic Chemistry 2016, no. 17 (April 4, 2016): 2667–75. http://dx.doi.org/10.1002/ejic.201600090.

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44

Goswami, Monalisa, and Bas de Bruin. "Metal-Catalysed Azidation of Organic Molecules." European Journal of Organic Chemistry 2017, no. 8 (December 22, 2016): 1152–76. http://dx.doi.org/10.1002/ejoc.201601390.

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45

Riyaz, Sayima, Ghulam Mustafa Peerzada, Nadeem Bashir Ganaie, and Usma Gull. "Kinetics of the Acetaminophen-Based Oscillatory Chemical Reaction with and without Ferroin as Catalyst: An Inorganic Prototype Model for Acetaminophen–Ethanol Syndrome." Progress in Reaction Kinetics and Mechanism 42, no. 2 (May 2017): 163–81. http://dx.doi.org/10.3184/146867817x14806858831901.

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This paper describes the nonlinear behaviour of the acetaminophen-based uncatalysed Belousov–Zhabotinsky oscillator and its dynamics in the presence of ferroin as catalyst. The role of free metal ions as catalysts was examined and the results compared with those of corresponding complexed catalysts. Free metal ions were found to be sluggish with respect to the evolution of the oscillatory regime as compared to complexed ones. The effect was monitored of change of the ligand moiety of the catalyst complex on the oscillatory parameters. Since ethanol potentiates the hepatotoxicity caused by acetaminophen in vivo, it is thought to understand this interaction by virtue of causing perturbation of the acetaminophen-based oscillator with different concentrations of ethanol with and without ferroin as catalyst. Another dimension to the ethanol effect was examined by perturbation of the system with ethanol at different stages of the reaction so as to get an idea as to whether it is acetaminophen or some reactive intermediate generated in the reaction system which reacts with ethanol. Further, the ferroin-catalysed oscillator is taken as a prototype inorganic model of the acetaminophen–ethanol syndrome, as ferroin and hypobromous acid (HOBr) act as inorganic replacements for cytochrome P450 and nicotinamide adenine dinucleotide phosphate (NADPH) in alcohol metabolism.

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Zhao, Da, Roland Petzold, Jiyao Yan, Dieter Muri, and Tobias Ritter. "Tritiation of aryl thianthrenium salts with a molecular palladium catalyst." Nature 600, no. 7889 (December 15, 2021): 444–49. http://dx.doi.org/10.1038/s41586-021-04007-y.

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AbstractTritium labelling is a critical tool for investigating the pharmacokinetic and pharmacodynamic properties of drugs, autoradiography, receptor binding and receptor occupancy studies1. Tritium gas is the preferred source of tritium for the preparation of labelled molecules because it is available in high isotopic purity2. The introduction of tritium labels from tritium gas is commonly achieved by heterogeneous transition-metal-catalysed tritiation of aryl (pseudo)halides. However, heterogeneous catalysts such as palladium supported on carbon operate through a reaction mechanism that also results in the reduction of other functional groups that are prominently featured in pharmaceuticals3. Homogeneous palladium catalysts can react chemoselectively with aryl (pseudo)halides but have not been used for hydrogenolysis reactions because, after required oxidative addition, they cannot split dihydrogen4. Here we report a homogenous hydrogenolysis reaction with a well defined, molecular palladium catalyst. We show how the thianthrene leaving group—which can be introduced selectively into pharmaceuticals by late-stage C–H functionalization5—differs in its coordinating ability to relevant palladium(II) catalysts from conventional leaving groups to enable the previously unrealized catalysis with dihydrogen. This distinct reactivity combined with the chemoselectivity of a well defined molecular palladium catalyst enables the tritiation of small-molecule pharmaceuticals that contain functionality that may otherwise not be tolerated by heterogeneous catalysts. The tritiation reaction does not require an inert atmosphere or dry conditions and is therefore practical and robust to execute, and could have an immediate impact in the discovery and development of pharmaceuticals.

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González-Belman, Oscar F., J. Oscar C. Jiménez-Halla, Fady Nahra, Catherine S. J. Cazin, and Albert Poater. "The role of the metal in the dual-metal catalysed hydrophenoxylation of diphenylacetylene." Catalysis Science & Technology 8, no. 14 (2018): 3638–48. http://dx.doi.org/10.1039/c8cy00510a.

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Nájera, Carmen, Irina P. Beletskaya, and Miguel Yus. "Metal-catalyzed regiodivergent organic reactions." Chemical Society Reviews 48, no. 16 (2019): 4515–618. http://dx.doi.org/10.1039/c8cs00872h.

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Woo, Ho K., R. Srinivasan, L. Rice, P. J. Reucroft, and R. J. De Angelis. "Reactivity and structure of nickel-cobalt bimetallic catalysts." Proceedings, annual meeting, Electron Microscopy Society of America 46 (1988): 698–99. http://dx.doi.org/10.1017/s0424820100105552.

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Ni and Co catalyst systems have been extensively dealt with in the catalyst research literature but investigations on Ni/Co alloy systems have been relatively sparse. An early study attempted to correlate catalysed hydrogenation activity with metal/alloy lattice parameter. Matsuyama et al. investigated catalytic hydrogenation of ethylene by nickel alloys as a function of surface and bulk composition. The activity increased as the proportion of Ni increased but decreased from 90 to 100%Ni. A study has been initiated to relate catalytic activity to the structure of Ni/Co bimetallic catalyst particles.Silica supported catalysts were prepared by the incipient wetness (impregnation) technique. Nickel, and cobalt nitrate in the desired proportions were dissolved in the impregnating solution. The wet catalyst samples were dried overnight at 120C after impregnation,. Catalysts were reduced by heating at 400C in flowing hydrogen for 18 hrs. Reactivity was determined by passing a 3/1 mixture of hydrogen and carbon monoxide over the catalyst and analyzing the effluent stream at hourly intervals by gas chromatography for hydrocarbon products.

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Sen, Ayusman. "Homogeneous Palladium(II) Mediated Oxidation of Methane." Platinum Metals Review 35, no. 3 (July 1, 1991): 126–32. http://dx.doi.org/10.1595/003214091x353126132.

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A metal catalysed, electrophilic approach to methane oxidation is discussed. This involves the oxidation of methane to the corresponding methyl ester in trifluoroacetic acid; the oxidant is hydrogen peroxide and the catalyst is the palladium(II) ion. The latter species activates methane by the electrophilic cleavage of a C-H bond, and then acts as a two-electron oxidant towards the resultant metal-bound methyl group. The hydrogen peroxide reoxidises palladium(0) back to palladium(II)

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