Artykuły w czasopismach: „Double Atom Catalysis”

1

Chen, Wei, Binbin Wu, Yanyong Wang, Wang Zhou, Yingying Li, Tianyang Liu, Chao Xie i in. "Deciphering the alternating synergy between interlayer Pt single-atom and NiFe layered double hydroxide for overall water splitting". Energy & Environmental Science 14, nr 12 (2021): 6428–40. http://dx.doi.org/10.1039/d1ee01395e.

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Shan, Hui, i Paul R. Sharp. "Double Oxygen Atom Centered Rhodium–Gold Clusters". Angewandte Chemie International Edition in English 35, nr 6 (1.04.1996): 635–36. http://dx.doi.org/10.1002/anie.199606351.

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Mark, Brian L., i Michael NG James. "Anchimeric assistance in hexosaminidases". Canadian Journal of Chemistry 80, nr 8 (1.08.2002): 1064–74. http://dx.doi.org/10.1139/v02-130.

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Configuration retaining glycosidases catalyse the hydrolysis of glycosidic bonds via a double displacement mechanism, typically involving two key active site carboxyl groups (Glu or Asp). One of the enzymic carboxyl groups functions as a general acidbase catalyst, the other acts as a nucleophile. Alternatively, configuration-retaining hexosaminidases from the sequence-related glycosidase families 18, 20, and 56 lack a suitably positioned enzymic nucleophile; instead, they use the carbonyl oxygen atom of the neighbouring C2-acetamido group of the substrate. The carbonyl oxygen atom of the 2-acetamido group provides anchimeric assistance to the enzyme catalyzed reaction by acting as an intramolecular nucleophile, attacking the anomeric center and forming a cyclized oxazolinium ion intermediate that is stereochemically equivalent to the glycosylenzyme intermediate formed in the "normal" double displacement mechanism. Although there is little sequence similarity between families 18, 20, and 56 hexosaminidases, X-ray crystallographic studies demonstrate that they have evolved similar catalytic domains and active site architectures that are designed to distort the bound substrate so that the C2-acetamido group can become appropriately positioned to participate in catalysis. The substrate distortion allows for a substrate-assisted catalytic reaction that displays all the general characteristics of the classic double-displacement mechanism including the formation of a covalent intermediate.Key words: glycoside hydrolase, hexosaminidase, glycosidase, substrate-assisted catalysis, anchimeric assistance.

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4

Cao, Rong, Jie-Zhen Xia i Qi Wu. "Computational Insight into Defective Boron Nitride Supported Double-Atom Catalysts for Electrochemical Nitrogen Reduction". Catalysts 12, nr 11 (10.11.2022): 1404. http://dx.doi.org/10.3390/catal12111404.

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Designing highly selective and efficient double-atom electrocatalysts (DACs) is essential for achieving a superior nitrogen-reduction reaction (NRR) performance. Herein, we explored the defective boron nitride–supported cage-like double-atom catalysts to rummage the qualified NRR catalysts. Based on a systematic evaluation of the stability, N2 adsorption, NRR selectivity and activity of 10 DACs of TM1-TM2@VB-BN, we predicted Ru-Ti@VB-BN to be the NRR candidate with a limiting potential of −0.40 V. Compared to the corresponding single-atom catalysts, the introduction of Ti/Mo modulates the d-band center of the active metal atom, which improves the NRR performance. Moreover, the magnetic Ru-Ti dimer can facilitate the transfer of charge to molecular N2, ensuring a significant activation of the inert N≡N bond. This research not only opens up new avenues for designing boron nitride–supported DACs for NRR, but also deepens the understanding of DACs in N2 activation.

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5

Cheng, Jian, Jin Xie i Chengjian Zhu. "Relay photocatalytic cascade reactions: synthesis of indolo[2,1-a]isoquinoline derivatives via double C(sp3)–H bond functionalization". Chemical Communications 54, nr 13 (2018): 1655–58. http://dx.doi.org/10.1039/c7cc09820k.

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A relay photoredox catalysis strategy concomitant with [1,5] hydrogen atom transfer has been applied in the construction of a biologically important indolo[2,1-a]isoquinoline framework via a cascade reaction. This reaction enables double C(sp³)–H bond functionalization and formation of two carbon–carbon double bonds.

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Wang, Zelin, Si-Min Xu, Yanqi Xu, Ling Tan, Xian Wang, Yufei Zhao, Haohong Duan i Yu-Fei Song. "Single Ru atoms with precise coordination on a monolayer layered double hydroxide for efficient electrooxidation catalysis". Chemical Science 10, nr 2 (2019): 378–84. http://dx.doi.org/10.1039/c8sc04480e.

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7

Wang, Yun, i Lihua Kang. "Selective Hydrogenation of Acetylene Catalysed by a B12N12 Cluster Doped with a Single Nickel Atom: A DFT Study". Catalysts 10, nr 1 (13.01.2020): 115. http://dx.doi.org/10.3390/catal10010115.

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To obtain a catalyst based on a non-precious metal that can replace traditional palladium-based selective catalysts of acetylene hydrogenation, the catalytic performances of two different configurations of a B12N12 cluster doped with a single nickel atom were studied by a density functional theory computational approach. After analysing the effect that the adsorption of reactants onto the clusters has on the reaction path, we determined the lowest energy path for the acetylene double hydrogenation. Comparing the acetylene hydrogenation activities and ethylene product selectivities of the B11N12Ni and B12N11Ni clusters, which have different doping sites, we determined the activities of these two catalysts to be similar to each other; however, the B11N12Ni cluster was calculated to have higher selectivity for ethylene as a product. This difference may be related to the moderate adsorption of hydrogen and acetylene on the B11N12Ni cluster. As a new type of nickel-based single-atom catalyst, B11N12Ni clusters may have research value in the selective hydrogenation of acetylene.

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8

Poulos, Thomas L. "Intermediates in P450 catalysis". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 363, nr 1829 (15.04.2005): 793–806. http://dx.doi.org/10.1098/rsta.2004.1537.

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Cytochromes P450 catalyse the insertion of one O 2 -derived oxygen atom in unactivated C–H bonds, and as such, are potent oxidants. A significant amount is known about the P450 catalytic cycle owing partly to the single heme group at the active site that provides spectroscopic handles in tracking various intermediates. A sophisticated array of electron paramagnetic, electron double nuclear resonance, and more traditional absorption spectroscopies have been able to identify key intermediates, while crystallography has defined the structure of the substrate-free, -bound, and oxy-complexes. What has remained elusive is the Fe(IV)=O intermediate, thought to be the active hydroxylating agent. Here, theory and especially density functional calculations have provided valuable insights.

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9

Zhang, Xi-Sha, Kang Chen i Zhang-Jie Shi. "Transition metal-catalyzed direct nucleophilic addition of C–H bonds to carbon–heteroatom double bonds". Chem. Sci. 5, nr 6 (2014): 2146–59. http://dx.doi.org/10.1039/c3sc53115e.

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Compared with the traditional Grignard reaction, direct insertion of polar double bonds to C–H bonds via transition-metal catalysis is ideal from the viewpoint of atom-, step- and cost-economy and the avoidance of the waste emission, as well as of the complex manipulation of sensitive reagents.

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Rasool, Anjumun, Insha Anis, Mudit Dixit, Ashakiran Maibam, Afshana Hassan, Sailaja Krishnamurty i Manzoor Ahmad Dar. "Tantalum based single, double, and triple atom catalysts supported on g-C₂N monolayer for effective nitrogen reduction reaction: a comparative DFT investigation". Catalysis Science & Technology 12, nr 1 (2022): 310–19. http://dx.doi.org/10.1039/d1cy01292d.

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Density functional theory simulations demonstrate that single and triple Ta-atom catalysts anchored to C2N monolayer act as superior catalysts for the nitrogen reduction reaction via alternating and distal pathways.

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Pearson-Long, Morwenna, Philippe Bertus, Julien Caillé, Mathilde Pantin i Fabien Boeda. "Zinc-Mediated Double Addition on Functionalized Nitriles". Synthesis 51, nr 06 (24.01.2019): 1329–41. http://dx.doi.org/10.1055/s-0037-1611704.

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Allylzinc reagents were used to access highly functionalized tertiary carbinamine derivatives in high yields from cyanoesters and cyanocarbonates. While the monoaddition of organometallics on nitriles is generally observed, in this work the nucleophilic allylation occurs twice, due to an intermediate transfer of the carbonyl moiety onto the nitrogen atom. The chemoselectivity of the reaction allows the presence of various functionalities and in the case of carbonate derivatives, the nature of the final product was modulated by kinetic control, giving selectively hydroxyamides or cyclic carbamates.

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12

Yu, Linke, i Fengyu Li. "Pt2 Dimer Anchored Vertically in Defective BN Monolayer as an Efficient Catalyst for N2 Reduction: A DFT Study". Catalysts 12, nr 11 (8.11.2022): 1387. http://dx.doi.org/10.3390/catal12111387.

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The electrochemical nitrogen reduction reaction (NRR) using clean energy is considered a promising alternative to the conventional Haber–Bosch process; however, developing a highly active electrocatalyst is still a great challenge. In this study, ten metal dimers anchored in a defective boron nitride (BN) monolayer as double-atom catalysts (DACs) with reverse sandwich structures were screened for their stability and catalytic activity towards NRR by density functional theory (DFT) calculations. Among them, three DACs (Rh2⊥vb-BN, Pt2⊥vb-BN and Rh2⊥vn-BN) were confirmed to be stable and have high promise as NRR electrocatalysts, and Pt2⊥vb-BN particularly distinguishes itself due to its very low limiting potential (−0.06 V). In addition, the electrocatalytic performance of all three DACs prevailed over that of their single-atom catalyst counterparts. We believe that the unique conformation of the reverse sandwich structure has impressive potential for the development of DACs, and we hope that our study provides a new design strategy for DACs for NRR and beyond.

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13

Anis, Insha, Mohd Saleem Dar, Ghulam Mohammad Rather i Manzoor Ahmad Dar. "Exploring the structure and electronic properties of germanium doped boron clusters using density functional theory based global optimization method". New Journal of Chemistry 46, nr 13 (2022): 6244–54. http://dx.doi.org/10.1039/d2nj00227b.

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14

El-Taher, Sabry. "Theoretical investigation of the oxidation pathways of HO•-initiated reactions of acrolein, methacrolein, and trans-crotonaldehyde". Canadian Journal of Chemistry 87, nr 12 (grudzień 2009): 1716–26. http://dx.doi.org/10.1139/v09-142.

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Ab initio molecular-orbital calculations have been performed to investigate the reaction mechanisms of the HO•-initiated reactions of the α,β-unsaturated aldehydes: acrolein (ACR), methacrolein (MACR), and trans-crotonaldehyde (CROT). All geometries were fully optimized at the MP2(Full)/6–31G(d,p) level. The correlation energy corrections were introduced by carrying out single-point calculations using both spin-projected second-order Møller–Plesset perturbation theory (PMP2) and coupled-cluster theory (CCSD(T)) using basis sets of different sizes. All reaction pathways studied proceed via a barrierless formation of a loosely bound pre-reactive complex in the entrance channel. The transition-state structures of the HO• additions to the terminal (β) and to the central (α) carbon atoms of the C=C double bond are found to be reactant-like structures. The lowest-energy barrier pathways are found to be the aldehydic H-atom abstraction. The β-addition pathways are found to be energetically more favored than the α-addition pathways. The HO• addition and aldehydic H-atom abstraction pathways are found to be highly exoergic, with the H-atom abstraction pathway being more exoergic than the addition pathways. Although the methyl substitution at the C=C double bond of methacrolein and crotonaldehyde lowers the energies of the transition-state structures of both α- and β-addition pathways, it destabilizes the energies of the transition-state structures of the corresponding aldehydic H-atom abstraction pathways, compared with that of acrolein.

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15

Khlebnikov, Alexander, Vladimir Bodunov, Ekaterina Galenko, Alexey Galenko i Mikhail Novikov. "Synthesis of Substituted Indole-3-carboxylates by Iron(II)-Catalyzed Domino Isomerization of 3-Alkyl/aryl-4-aryl-5-methoxyisoxazoles". Synthesis 50, nr 14 (29.05.2018): 2784–98. http://dx.doi.org/10.1055/s-0036-1591576.

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The iron(II)-catalyzed domino isomerization of 3-alkyl/aryl-4-arylisoxazoles provides a selective access to a wide range of structurally diverse highly substituted indole-3-carboxylates. The operational simplicity, high atom efficiency, and the use of stable starting materials and an inexpensive and low-toxicity catalyst are some of the attractive features of this tandem double ring-opening–ring-closure strategy.

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16

Bai, Lichen, Chia-Shuo Hsu, Duncan T. L. Alexander, Hao Ming Chen i Xile Hu. "A Cobalt–Iron Double-Atom Catalyst for the Oxygen Evolution Reaction". Journal of the American Chemical Society 141, nr 36 (16.08.2019): 14190–99. http://dx.doi.org/10.1021/jacs.9b05268.

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Liu, Ce, Teng Li, Xingchao Dai, Jian Zhao, Dongcheng He, Guomin Li, Bin Wang i Xinjiang Cui. "Catalytic Activity Enhancement on Alcohol Dehydrogenation via Directing Reaction Pathways from Single- to Double-Atom Catalysis". Journal of the American Chemical Society 144, nr 11 (9.03.2022): 4913–24. http://dx.doi.org/10.1021/jacs.1c12705.

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18

Chang, Meng-Yang, i Kai-Xiang Lai. "Palladium(II) Acetate Mediated Dimerization/Cycloisomerization of 2-Sulfonyl-4-alkynones: Synthesis of trans-1,2-Difurylethylenes". Synthesis 51, nr 18 (23.05.2019): 3410–18. http://dx.doi.org/10.1055/s-0037-1611567.

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This paper describes a one-pot, atom-economic, easy-operation, open-atmosphere method for the synthesis of trans-1,2-difurylethylenes by the straightforward Pd(OAc)2-mediated dimerization/cycloisomerization of 2-sulfonyl-4-alkynones in the presence of Na2CO3 and PPh3 under refluxing EtOH conditions, and proposes and discusses a plausible mechanism. This protocol provides a highly effective annulation via two carbon–oxygen (C–O) single-bond and one carbon–carbon (C=C) double-bond formations.

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Chiang, Yvonne, Robert Eliason, Gary H. X. Guo i A. Jerry Kresge. "Vinyl ether hydrolysis. XXIX. 1-Methoxy-1,3-butadiene: reaction mechanism and implication for hydrolysis of the mutagen fecapentaene-12". Canadian Journal of Chemistry 72, nr 7 (1.07.1994): 1632–36. http://dx.doi.org/10.1139/v94-205.

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The hydrolysis of cis- and trans-1-methoxy-1,3-butadiene in aqueous solution occurs by hydron transfer to the δ-carbon atom with little or no β-hydronation to give crotonaldehyde as essentially the sole aldehyde product. The reaction gives appreciable hydronium-ion isotope effects in the normal direction [Formula: see text] and shows general acid catalysis; five carboxylic acid catalytic coefficients for hydrolysis of the trans isomer give a good Brønsted relation with the exponent α = 0.59. This is taken as evidence that these reactions occur by the conventional mechanism for vinyl ether hydrolysis involving rate-determining hydron transfer to substrate carbon followed by rapid formation and decomposition of a hemiacetal intermediate. Comparison of the reactivity of the present dienyl ethers with that of their monoenyl analog, methyl vinyl ether, shows that introduction of the second double bond decreases reactivity considerably: the hydronium-ion catalytic coefficient is reduced by a factor of 8.3 for the trans isomer and by a factor of 160 for the cis isomer. This reduction supports a hypothesis advanced to explain the occurrence of reaction by a different mechanism recently discovered in the hydrolysis of the strongly mutagenic polyenyl ether, fecapentaene-12.

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20

David, Michèle, Jean Sauleau i Armelle Sauleau. "Époxydes α-éthyléniques et phénate de sodium: accès à des éthers phénoliques et phénols ortho-allyliques". Canadian Journal of Chemistry 63, nr 9 (1.09.1985): 2449–54. http://dx.doi.org/10.1139/v85-405.

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The ring cleavage reactions of α-ethylenic epoxides by sodium phenoxide afforded a mixture of products. Problems of competitive attack by this nucleophile, at the less substituted carbon (compounds A) or at the β-ethylenic carbon atom (compounds B and C), were encountered and could be resolved by judicious choice of reaction conditions (solvents, stereochemistry of the oxiranes). The regioselectivity of the attack was dependent on the transition states, implying weak steric hindrance and a conjugation oxirane – double bond.

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21

Arnaud, R., S. Choubani, R. Subra, M. Vidal, M. Vincens i V. Barone. "Le radical méthylènecyclopropyle: étude théorique. Chloration par t-BuOCl et réduction par (nBu)3SnH de dérivés cyclopropéniques". Canadian Journal of Chemistry 63, nr 9 (1.09.1985): 2511–21. http://dx.doi.org/10.1139/v85-416.

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The allylic chlorination of ethyl 2,3-dialkyl 2-cyclopropenecarboxylate or primary and tertiary alcohols is highly regio- and stereoselective. The halogenated methylenecyclopropane derivative only is observed. In that compound, the halogen substituent and the functional group are in a trans position with respect to the ring. The halogenated allylic compounds of methylenecyclopropane and of cyclopropene undergo reduction by (nBu)3SnH with the same stereochemistry. Products arising from ring opening are also observed. The exocyclic migration of the double bond can be related to the formation of a transient allylic radical. A theoretical study performed within the MNDO (UHF and RHF) framework leads to a planar allylic radical, whatever the substituent. The radical abstraction reaction which takes place during the reduction process is easier for a cyclic carbon atom than for an exocyclic one. In the former case, the faster reaction is obtained for a chlorinated carbon atom.

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22

Filippov, Andrey S., Svetlana V. Amosova, Alexander I. Albanov i Vladimir A. Potapov. "Regioselective Synthesis of Novel Functionalized Dihydro-1,4-thiaselenin-2-ylsufanyl Derivatives under Phase Transfer Catalysis". Catalysts 12, nr 8 (12.08.2022): 889. http://dx.doi.org/10.3390/catal12080889.

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The regioselective one-pot synthesis of novel functionalized 2,3-dihydro-1,4-thiaselenin-2-ylsufanyl derivatives in high yields based on 2-bromomethyl-1,3-thiaselenole and activated alkenes was developed under phase transfer catalysis conditions. The reactions proceed under mild conditions at room temperature in a regioselective manner with the addition of sodium dihydro-1,4-thiaselenin-2-ylthiolate exclusively at the terminal carbon atom of the double bond of vinyl methyl ketone, alkylacrylates, acrylamide, acrylonitrile, divinyl sulfone, and divinyl sulfoxide. The sodium dihydro-1,4-thiaselenin-2-ylthiolate was generated from 2-[amino(imino)methyl]sulfanyl-2,3-dihydro-1,4-thiaselenine hydrobromide. The latter compound was obtained by the reaction of 2-bromomethyl-1,3-thiaselenole with thiourea, which was accompanied by a rearrangement with ring expansion to the six-membered heterocycle. The obtained 2,3-dihydro-1,4-thiaselenin-2-ylsufanyl derivatives are a novel family of compounds with putative biological activity. The addition products of sodium dihydro-1,4-thiaselenin-2-ylthiolate at one double bond of divinyl sulfone and divinyl sulfoxide, containing vinylsulfonyl and vinylsulfinyl groups, are capable of further addition reactions. A possibility to obtain corresponding alcohol derivatives was shown in the reaction with vinyl methyl ketone.

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23

Lo, John M. H., Robert A. Marriott, Binod R. Giri, John M. Roscoe i Mariusz Klobukowski. "A theoretical analysis of the kinetics of the reaction of atomic bromine with tetrahydrofuran". Canadian Journal of Chemistry 88, nr 11 (listopad 2010): 1136–45. http://dx.doi.org/10.1139/v10-092.

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The kinetic behaviour for the reaction of atomic bromine with tetrahydrofuran has been analysed using the information from quantum chemical calculations. Structures and energy profiles were first obtained using density functional theory (DFT) employing the Dunning’s basis sets of triple-zeta quality, and then for an accurate energetic description, single-point calculations were carried out at the coupled-cluster with single and double excitations (CCSD) and the fourth-order Møller–Plesset (MP4(SDQ)) levels of theory. The rate coefficients and the equilibrium constants for the potential reaction channels were obtained from the statistical rate theories and statistical thermodynamics, respectively, using the results of quantum chemical calculations; and the results were compared with our recently published experimental data. In terms of reaction mechanism, this reaction was found to be analogous to the reactions of the Br atom with 1,4-dioxane and with methanol, where the reaction proceeds via an addition–elimination mechanism. The dominant reaction channel involved coordination of the approaching Br atom to one of the hydrogen atoms adjacent to the ether oxygen atom, i.e., β-hydrogen abstraction is uncompetitive. Although the complexes formed by direct coordination of the Br atom to the ether oxygen atom appeared in the reaction mechanism, we were not able to link them specifically to any reaction. The density functional theory predicted an activation energy and enthalpy of reaction that were much smaller than the experimental values, which led to an overestimation of the theoretical rate coefficients. The source of this discrepancy could be attributed to the overbinding of the transition states and of the tetrahydrofuranyl radical by DFT. Single-point calculations at the DFT structures using the CCSD and MP4(SDQ) methods yielded an accurate energetic description of the reaction of tetrahydrofuran with bromine, resulting in rate coefficients that showed excellent agreement with the experimental values.

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Cowie, Bradley E., Gary S. Nichol, Jason B. Love i Polly L. Arnold. "Double uranium oxo cations derived from uranyl by borane or silane reduction". Chemical Communications 54, nr 31 (2018): 3839–42. http://dx.doi.org/10.1039/c8cc00341f.

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Onwukwe, Goodluck U., M. Kristian Koski, Petri Pihko, Werner Schmitz i Rik K. Wierenga. "Structures of yeast peroxisomal Δ3,Δ2-enoyl-CoA isomerase complexed with acyl-CoA substrate analogues: the importance of hydrogen-bond networks for the reactivity of the catalytic base and the oxyanion hole". Acta Crystallographica Section D Biological Crystallography 71, nr 11 (27.10.2015): 2178–91. http://dx.doi.org/10.1107/s139900471501559x.

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Δ3,Δ2-Enoyl-CoA isomerases (ECIs) catalyze the shift of a double bond from 3Z- or 3E-enoyl-CoA to 2E-enoyl-CoA. ECIs are members of the crotonase superfamily. The crotonase framework is used by many enzymes to catalyze a wide range of reactions on acyl-CoA thioesters. The thioester O atom is bound in a conserved oxyanion hole. Here, the mode of binding of acyl-CoA substrate analogues to peroxisomal Saccharomyces cerevisiae ECI (ScECI2) is described. The best defined part of the bound acyl-CoA molecules is the 3′,5′-diphosphate-adenosine moiety, which interacts with residues of loop 1 and loop 2, whereas the pantetheine part is the least well defined. The catalytic base, Glu158, is hydrogen-bonded to the Asn101 side chain and is further hydrogen-bonded to the side chain of Arg100 in the apo structure. Arg100 is completely buried in the apo structure and a conformational change of the Arg100 side chain appears to be important for substrate binding and catalysis. The oxyanion hole is formed by the NH groups of Ala70 (loop 2) and Leu126 (helix 3). The O atoms of the corresponding peptide units, Gly69 O and Gly125 O, are both part of extensive hydrogen-bond networks. These hydrogen-bond networks are a conserved feature of the crotonase oxyanion hole and their importance for catalysis is discussed.

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Chiarucci, Michel, i Marco Bandini. "New developments in gold-catalyzed manipulation of inactivated alkenes". Beilstein Journal of Organic Chemistry 9 (21.11.2013): 2586–614. http://dx.doi.org/10.3762/bjoc.9.294.

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Over the recent years, the nucleophilic manipulation of inactivated carbon–carbon double bonds has gained remarkable credit in the chemical community. As a matter of fact, despite lower reactivity with respect to alkynyl and allenyl counterparts, chemical functionalization of isolated alkenes, via carbon- as well as hetero atom-based nucleophiles, would provide direct access to theoretically unlimited added value of molecular motifs. In this context, homogenous [Au(I)] and [Au(III)] catalysis continues to inspire developments within organic synthesis, providing reliable responses to this interrogative, by combining crucial aspects such as chemical selectivity/efficiency with mild reaction parameters. This review intends to summarize the recent progresses in the field, with particular emphasis on mechanistic details.

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Wu, Yingxi, Hongyan Wang, Yuexia Lin, Simin Gao i Feng Zhang. "Hydrogen-bonded proton transfer in the hydrated adenine–thymine anion". Canadian Journal of Chemistry 91, nr 10 (październik 2013): 992–98. http://dx.doi.org/10.1139/cjc-2013-0162.

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The proton transfer processes of microhydrated adenine–thymine anions are studied using density functional theory with the B3LYP method and DZP++ basis set. The microhydration effects on the geometrical structures, adsorption site, and the proton transfer reaction of the adenine–thymine anion are investigated. The site N10 atom of the adenine moiety has a larger proton affinity than the site O24 atom of thymine, which facilitates the proton H26 transfers from the N25 site of thymine to the N10 site of adenine. Therefore, the first single-proton transfer pathway (SPT1) is found for the all of the monohydrated adenine–thymine anions (AN4T)−·H2O, (AN13T)−·H2O, (ATO24)−·H2O, and (ATO28)−·H2O and tetrahydrated adenine–thymine anions (AT)−·4H2O. The proton H9 at the N7 site of adenine is also found to transfer to the O24 site of thymine for (AN4T)−·H2O and (AN13T)−·H2O in the gas phase. The double-proton transferred pathway is found when one water molecule interacts with the O28 atom of thymine. The reactant structures before the proton transfer are more stable than the product structures, and the structural changes mainly occur in thymine. The reaction energies of the microhydrated adenine–thymine anion in the gas phase and in the aqueous environment predict that the proton transfer process of the microhydrated adenine–thymine anion are more favorable in the gas phase than in aqueous solution.

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Liu, Fan, Ning Yan, Guangqi Zhu, Zigeng Liu, Shenqian Ma, Guolei Xiang, Songrui Wang, Xingjiang Liu i Wei Wang. "Fe–N–C single-atom catalysts with an axial structure prepared by a new design and synthesis method for ORR". New Journal of Chemistry 45, nr 29 (2021): 13004–14. http://dx.doi.org/10.1039/d1nj01380g.

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FePc powder sublimates losing H atoms to form unstable fragments at 450 °C which self-assemble to form units with a double-layer structure. The self-assembly units are driven by argon gas at 70 °C to where the substrate is located and crystallize to form Fe-N5/C@G catalyst.

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Zhang, Jin, i Wei An. "Single-, double-, and triple-atom catalysts on graphene-like C₂N enable electrocatalytic nitrogen reduction: insight from first principles". Catalysis Science & Technology 12, nr 8 (2022): 2604–17. http://dx.doi.org/10.1039/d1cy02254g.

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The *NHx intermediates on Mn@C2N are highly stable for n = 3 and unstable for n = 1, rendering Mn@C2N as the optimal candidate for driving the eNRR owing to its moderate binding with NHx (x = 0, 1, 2, 3).

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30

Filkina, Maria E., Daria N. Baray, Elena K. Beloglazkina, Yuri K. Grishin, Vitaly A. Roznyatovsky i Maxim E. Kukushkin. "Regioselective Cycloaddition of Nitrile Imines to 5-Methylidene-3-phenyl-hydantoin: Synthesis and DFT Calculations". International Journal of Molecular Sciences 24, nr 2 (9.01.2023): 1289. http://dx.doi.org/10.3390/ijms24021289.

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Nitrile imine cycloaddition to hydantoins containing an exocyclic C=C double bond has been previously described in a very limited number of examples. In this work, regioselective synthesis of spiro-pyrazoline-imidazolidine-2,4-diones based on a 1,3-dipolar cycloaddition reaction of nitrile imines to 5-methylidene-3-phenyl-hydantoin have been proposed. It was found that, regardless of the nature of the aryl substituents at the terminal C and N atoms of the C-N-N fragment of nitrile imine (electron donor or electron acceptor), cycloaddition to the 5-methylidenhydantoin exocyclic C=C bond proceeds regioselectively, and the terminal nitrogen atom of the nitrile imine connects to the more sterically hindered carbon atom of the double bond, which leads to the formation of a 5-disubstituted pyrazoline ring. The observed cycloaddition regioselectivity was rationalized using DFT calculations of frontier molecular orbital interactions, global CDFT reactivity indices, and minimum energy paths.

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31

Yang, Weijie, Binghui Zhou, Yongqian Zhang, Jianuo Ren, Chongchong Wu, Ian D. Gates, Yanfeng Liu i Zhengyang Gao. "A novel low-temperature Fe-Fe double-atom catalyst for a “fast SCR” reaction". Molecular Catalysis 533 (grudzień 2022): 112769. http://dx.doi.org/10.1016/j.mcat.2022.112769.

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32

Jewell, Deborah Rae, Lukose Mathew i John Warkentin. "Rate constant for chlorine abstraction from CCl4 by the 5-hexenyl radical". Canadian Journal of Chemistry 65, nr 2 (1.02.1987): 311–15. http://dx.doi.org/10.1139/v87-052.

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Cyclization of the 5-hexenyl free radical to the cyclopentylmethyl free radical was used to clock chlorine atom abstraction by 5-hexenyl from carbon tetrachloride in solution. The source of 5-hexenyl radicals was 5-hexenyl[1-hydroxy-1-methyl-ethyl]diazene ((CH3)2C(OH)N=N(CH2)4CH=CH2), which decomposes thermally in CCl4 by a radical chain mechanism to afford chloroform, acetone, nitrogen, 6-chloro-1-hexene, cyclopentylchloromethane, 1-hexene, and methylcyclopentane as primary products. 6-Chloro-1-hexene is converted, in part, to a secondary product, 1,1,1,3,7-pentachloroheptane, by radical chain addition of CC14 to the double bond. The rate constant for chlorine atom abstraction, kCl, was calculated from the product composition and the known rate constant for cyclization of the 5-hexenyl radical. For the temperature range 274–353 K, kCl is given by log (kCl/M−1 s−1) = (8.4 ± 0.3) − (6.2 ± 0.4)/θ where θ = 2.3 RT kcal mol−1, which leads to [Formula: see text]. This value is significantly smaller than recently reported estimates for other primary alkyl radicals.

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33

Wel, Hans van der, Nico M. M. Nibbering i Margaret M. Kayser. "A gas phase study of the regioselective BH4− reduction of some 2-substituted maleic anhydrides". Canadian Journal of Chemistry 66, nr 10 (1.10.1988): 2587–94. http://dx.doi.org/10.1139/v88-406.

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Gas phase ion/molecule reactions in a Fourier transform ion cyclotron resonance mass spectrometer have been carried out for reductions of isotopically labelled citraconic (methylmaleic), phenylmaleic, and ethoxymaleic anhydrides by BH4−. In citraconic anhydride the carbonyl group neighbouring the methyl substituent is reduced preferentially in agreement with the ab initio calculations, which show the higher LUMO coefficients at this site. Hydride ion transfer to the olefinic double bond occurs as well; however, in that case no preference for either of the carbon atoms is observed. In phenylmaleic anhydride strong indications are found for a theoretically unexpected hydride ion transfer to the phenyl ring. For ethoxymaleic anhydride experimental evidence is presented showing hydride ion transfer to the carbon atom carrying the ethoxy group, which is in agreement with the "best overlap" consideration predicting that this carbon atom bears the highest LUMO coefficient.Most of the hydride transfers from BH4− to the molecules studied seem, therefore, to take place under orbital control rather than under control of long-range ion-induced dipole interactions between reactants.

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34

Stoyanov, Evgenii S., Irina Yu Bagryanskaya i Irina V. Stoyanova. "Substitution of H Atoms in Unsaturated (Vinyl-Type) Carbocations by Cl or O Atoms". International Journal of Molecular Sciences 24, nr 13 (27.06.2023): 10734. http://dx.doi.org/10.3390/ijms241310734.

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Introduction of Cl and O atoms into C4-vinyl carbocations was studied by X-ray diffraction analysis and IR spectroscopy. Chlorine atoms are weak electron acceptors in ordinary molecules but, within vinyl carbocations, manifest themselves as strong electron donors that accept a positive charge. The attachment of a Cl atom directly to a C=C bond leads to an increase in the e-density on it, exceeding that of the common double bond. The positive charge should be concentrated on the Cl atom, and weak δ− may appear on the C=C bond. More distant attachment of the Cl atom, e.g., to a C atom adjacent to the C=C bond, has a weaker effect on it. If two Cl atoms are attached to the Cγ atom of the vinyl cation, as in Cl2CγCδHCαHCH3, then the cation switches to the allyl type with two practically equivalent and almost uncharged CγCδCα bonds. When such a strong nucleophile as the O atom is introduced into the carbocation, a protonated ester molecule with a C–O(H+)–C group and a C=C bond forms. Nonetheless, in the future, there is still a possibility of obtaining carbocations with a non-protonated C–O–C group.

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35

Daloze, D., J. C. Braekman, P. Vanhecke, J. L. Boevé i J. M. Pasteels. "Long chain electrophilic contact poisons from the Dufour's gland of the ant Crematogasterscutellaris (Hymenoptera, Myrmicinae)". Canadian Journal of Chemistry 65, nr 2 (1.02.1987): 432–36. http://dx.doi.org/10.1139/v87-073.

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The Dufour's gland secretion of C. scutellaris contains a series of C23 long chain derivatives characterized by the presence of a cross-conjugated dienone linked to either a primary acetate, an aldehyde, or a carboxylic acid function. These compounds further differ from each other by the degree of unsaturation and (or) the position of an isolated double bond in the carbon atom chain. A combination of spectroscopic data and chemical degradations led to structures 1a–c, 2a–c, and 5a–c for the major components of the secretion. The highly electrophilic character of these compounds accounts for their efficiency as contact poisons.

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36

Robinson, E. A. "The duodecet rule: Part 3. Fluoro species of the third period elements". Canadian Journal of Chemistry 70, nr 6 (1.06.1992): 1696–705. http://dx.doi.org/10.1139/v92-213.

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On the basis of the suggested new value of 54 pm for the single bond covalent radius of fluorine, the previously established duodecetrule for period 3 elements in molecular species with highly electronegative ligands is extended to fluorides. It is shown, for species such as SiF4, (F3Si)2O, F3SiNH2, F3PO, and PF5, that the observed bond lengths are consistent with significant partial double bonding involving all the ligands, including fluorine, and with a total of six electron pairs in the valence shell of the central atom. Empirical rules based on d/d1, the ratio of an observed bond length to the corresponding single bond length calculated from the sum of covalent radii, are developed as a simple approximate guide to the extent of partial double bonding in bonds to third period elements. It is also shown that bond lengths in species such as Al2F5, AlO45−, and Al(NH2)4− are consistent with a duodecet rule.

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37

Mironenko, Roman M., Elina R. Saybulina, Liudmila N. Stepanova, Tatiana I. Gulyaeva, Mikhail V. Trenikhin, Konstantin S. Rodygin i Valentine P. Ananikov. "Sustainable Hydrogenation of Vinyl Derivatives Using Pd/C Catalysts". Catalysts 11, nr 2 (28.01.2021): 179. http://dx.doi.org/10.3390/catal11020179.

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The hydrogenation of unsaturated double bonds with molecular hydrogen is an efficient atom-economic approach to the production of a wide range of fine chemicals. In contrast to a number of reducing reagents typically involved in organic synthesis, hydrogenation with H2 is much more sustainable since it does not produce wastes (i.e., reducing reagent residues). However, its full sustainable potential may be achieved only in the case of easily separable catalysts and high reaction selectivity. In this work, various Pd/C catalysts were used for the liquid-phase hydrogenation of O-, S-, and N-vinyl derivatives with molecular hydrogen under mild reaction conditions (room temperature, pressure of 1 MPa). Complete conversion and high hydrogenation selectivity (>99%) were achieved by adjusting the type of Pd/C catalyst. Thus, the proposed procedure can be used as a sustainable method for vinyl group transformation by hydrogenation reactions. The discovery of the stability of active vinyl functional groups conjugated with heteroatoms (O, S, and N) under hydrogenation conditions over Pd/C catalysts opens the way for many useful transformations.

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38

Yang, Shaowei, Chen Wu, Jinhui Wang, Haidong Shen, Kai Zhu, Xi Zhang, Yueling Cao, Qiuyu Zhang i Hepeng Zhang. "Metal Single-Atom and Nanoparticle Double-Active-Site Relay Catalysts: Design, Preparation, and Application to the Oxidation of 5-Hydroxymethylfurfural". ACS Catalysis 12, nr 2 (3.01.2022): 971–81. http://dx.doi.org/10.1021/acscatal.1c05236.

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39

Wang, Mei Han, Hao Lei, Jia Xing Wen, Yutaka Sawada, Yoichi Hoshi, Takayuki Uchida i Zhao Xia Hou. "Research Progress in Gasochromics Mechanism of Tungsten Oxide Thin Films". Advanced Materials Research 1070-1072 (grudzień 2014): 471–74. http://dx.doi.org/10.4028/www.scientific.net/amr.1070-1072.471.

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The gasochromic effect and its potential applications of tungsten oxide (WO3) thin films are introduced. The research progress in gasochromics mechanism of WO3films is reviewed and various mechanism models are summarized and discussed. The double injection model, oxygen vacancy diffusion model and localized water molecules model are extensively used to explain the gasochromic coloration of WO3films. A perspective on the gasochromics mechanism development of WO3films is tended to fabricate WO3film with single crystal and regular structure, which may simply the quantitative characterizations induced by the complicated structure. Elucidating gasochromics mechanism of WO3films not only helps to understand gasochromic coloration phenomenon well but also improves the performance of gasochromic coloration devices. It also accelerates the development of the relative science, such as gas detector, atom/ion transport material, surface catalysis of semiconductor, and so on.

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40

Freindorf, Marek, i Elfi Kraka. "Mechanistic Details of the Sharpless Epoxidation of Allylic Alcohols—A Combined URVA and Local Mode Study". Catalysts 12, nr 7 (18.07.2022): 789. http://dx.doi.org/10.3390/catal12070789.

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In this work, we investigated the catalytic effects of a Sharpless dimeric titanium (IV)–tartrate–diester catalyst on the epoxidation of allylalcohol with methyl–hydroperoxide considering four different orientations of the reacting species coordinated at the titanium atom (reactions R1–R4) as well as a model for the non-catalyzed reaction (reaction R0). As major analysis tools, we applied the URVA (Unified Reaction Valley Approach) and LMA (Local Mode Analysis), both being based on vibrational spectroscopy and complemented by a QTAIM analysis of the electron density calculated at the DFT level of theory. The energetics of each reaction were recalculated at the DLPNO-CCSD(T) level of theory. The URVA curvature profiles identified the important chemical events of all five reactions as peroxide OO bond cleavage taking place before the TS (i.e., accounting for the energy barrier) and epoxide CO bond formation together with rehybridization of the carbon atoms of the targeted CC double bond after the TS. The energy decomposition into reaction phase contribution phases showed that the major effect of the catalyst is the weakening of the OO bond to be broken and replacement of OH bond breakage in the non-catalyzed reaction by an energetically more favorable TiO bond breakage. LMA performed at all stationary points rounded up the investigation (i) quantifying OO bond weakening of the oxidizing peroxide upon coordination at the metal atom, (ii) showing that a more synchronous formation of the new CO epoxide bonds correlates with smaller bond strength differences between these bonds, and (iii) elucidating the different roles of the three TiO bonds formed between catalyst and reactants and their interplay as orchestrated by the Sharpless catalyst. We hope that this article will inspire the computational community to use URVA complemented with LMA in the future as an efficient mechanistic tool for the optimization and fine-tuning of current Sharpless catalysts and for the design new of catalysts for epoxidation reactions.

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41

Yan, Yan, Haoyan Cheng, Zehua Qu, Rui Yu, Fan Liu, Qianwen Ma, Shuang Zhao i in. "Recent progress on the synthesis and oxygen reduction applications of Fe-based single-atom and double-atom catalysts". Journal of Materials Chemistry A 9, nr 35 (2021): 19489–507. http://dx.doi.org/10.1039/d1ta02769g.

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42

Chen, Hongyu, Ying Zhang, Qian He, Hao Zhang, Sheng Xu, Xiaohui He i Hongbing Ji. "A facile route to fabricate double atom catalysts with controllable atomic spacing for the r-WGS reaction". Journal of Materials Chemistry A 8, nr 5 (2020): 2364–68. http://dx.doi.org/10.1039/c9ta13192b.

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Four double atom catalysts (DACs) with controllable interatomic distances were achieved via solventless ball-milling, among which double-atom Ni₂/N–C showed good selectivity and superior catalytic activity to single-atom Ni₁/N–C for r-WGS reactions.

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43

Duncombe, Bridgette J., Lijlijana Pukar, Bohan Wu i Anthony J. Stace. "Gas-phase experiments on the chemistry and coordination of Zn(II) by aprotic solvent molecules". Canadian Journal of Chemistry 83, nr 11 (1.11.2005): 1994–2004. http://dx.doi.org/10.1139/v05-203.

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Experiments have been performed in the gas phase on a series of doubly charged zincligand complexes to elucidate their solvation structure and available fragmentation pathways. Production of such complexes was achieved by the formation of neutral argonligand clusters followed by the subsequent addition of a single zinc atom using a pickup technique. Multiply charged ions were then produced by electron impact within a high resolution, double-focusing mass spectrometer. Studies have been undertaken on a number of zinc(II) aprotic solvent complexes including those consisting of argon and carbon dioxide in association with the zinc cation. Investigation of these novel metalsolvent clusters took the form of recorded parent ion intensity distributions and the measurement of fragmentation patterns promoted via collision-induced dissociation (CID). Discussion of the intensity distributions is presented in terms of the solvation of Zn(II) by each solvent, drawing on existing theoretical and experimental data from the gaseous and condensed phases. Investigation of collision-induced dissociation processes includes identifying charge transfer reactions in each solvated system, and analysis of the results in terms of kinetic energy release as well as possible mechanisms for fragmentation pathways. Key words: zinc, clusters, dications, gas phase, solvation.

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44

Zhang, Hailong, Romain Carlino, Régis Guillot, Richard Gil, Sophie Bezzenine i Jérôme Hannedouche. "Substrate-Dependent Selectivity in Sc(OTf)3-Catalyzed Cyclization of Alkenoic Acids and N-Protected Alkenamides". Catalysts 12, nr 11 (20.11.2022): 1481. http://dx.doi.org/10.3390/catal12111481.

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Five- and six-membered ring lactones and lactams are ubiquitous frameworks in various natural and synthetic molecules and are key building blocks in organic synthesis. Catalytic addition of an O-H or N-H bond across an unactivated C–C double bond is an appealing approach to rapidly access such highly valuable N- and O-containing skeletons in a waste-free and 100% atom efficient process. Herein, we report, for the first time, the efficient and high-yield cyclization of δ/ε-alkenoic acids and N-protected δ-alkenamides catalyzedby practical and easily accessible Lewis acid scandium(III) triflate under thermal and microwave conditions. The selectivity outcome of the reaction of δ/ε-alkenoic acids was dependent on the substitution patterns of the backbone chain and alkene moiety, leading to the exclusive formation of either the corresponding γ/δ-lactones via an O-selective cyclization or the Friedel–Crafts-type product by C-selective cyclization. An uncommon and rarely disclosed O-selective cyclization occurred preferentially or exclusively when N-protected δ-alkenamides were engaged in the reaction. The atom selectivity of the cyclization was unambiguously confirmed by single crystal X-ray crystallography.

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45

Bax, Ben, Chun-wa Chung i Colin Edge. "Getting the chemistry right: protonation, tautomers and the importance of H atoms in biological chemistry". Acta Crystallographica Section D Structural Biology 73, nr 2 (1.02.2017): 131–40. http://dx.doi.org/10.1107/s2059798316020283.

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There are more H atoms than any other type of atom in an X-ray crystal structure of a protein–ligand complex, but as H atoms only have one electron they diffract X-rays weakly and are `hard to see'. The positions of many H atoms can be inferred by our chemical knowledge, and such H atoms can be added with confidence in `riding positions'. For some chemical groups, however, there is more ambiguity over the possible hydrogen placements, for example hydroxyls and groups that can exist in multiple protonation states or tautomeric forms. This ambiguity is far from rare, since about 25% of drugs have more than one tautomeric form. This paper focuses on the most common, `prototropic', tautomers, which are isomers that readily interconvert by the exchange of an H atom accompanied by the switch of a single and an adjacent double bond. Hydrogen-exchange rates and different protonation states of compounds (e.g. buffers) are also briefly discussed. The difference in heavy (non-H) atom positions between two tautomers can be small, and careful refinement of all possible tautomers may single out the likely bound ligand tautomer. Experimental methods to determine H-atom positions, such as neutron crystallography, are often technically challenging. Therefore, chemical knowledge and computational approaches are frequently used in conjugation with experimental data to deduce the bound tautomer state. Proton movement is a key feature of many enzymatic reactions, so understanding the orchestration of hydrogen/proton motion is of critical importance to biological chemistry. For example, structural studies have suggested that, just as a chemist may use heat, some enzymes use directional movement to protonate specific O atoms on phosphates to catalyse phosphotransferase reactions. To inhibit `wriggly' enzymes that use movement to effect catalysis, it may be advantageous to have inhibitors that can maintain favourable contacts by adopting different tautomers as the enzyme `wriggles'.

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46

Kresge, A. J., M. Leibovitch i K. R. Kopecky. "Acid-catalyzed hydrolysis of tetramethoxyethene in aqueous solution. Initial state stabilization by the methoxy groups". Canadian Journal of Chemistry 68, nr 10 (1.10.1990): 1786–90. http://dx.doi.org/10.1139/v90-278.

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The acid-catalyzed hydrolysis of tetramethoxyethene to methyl dimethoxyacetate in aqueous solution at 25 °C was found to occur with the hydronium-ion catalytic coefficient [Formula: see text], to give the solvent isotope effect [Formula: see text], and to provide a Brønsted relation based upon six carboxylic acids with the exponent α = 0.42. These data indicate that the reaction proceeds via rate-determining proton transfer from the catalyzing acid to an olefinic carbon atom of the substrate. They also show tetramethoxyethene to be 1.0 × 106 times less reactive than 1,1-dimethoxyethene (ketene dimethyl acetal), a rate retardation 600 times greater than that expected from initial state stabilization by the two additional methoxy groups in tetramethoxyethene; possible causes of this disparity are discussed. Keywords: tetramethoxyethene, carbon–carbon double bond reactivity, ketene acetal, vinyl ether hydrolysis.

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47

Powell, Donald A., William S. York, Herman van Halbeek, Joseph T. Etse, Alexander I. Gray i Peter G. Waterman. "Structural characterization, by two-dimensional NMR spectroscopy and fast-atom-bombardment mass spectrometry, of a highly acylated trirhamnoside from Mezzettialeptopoda (Annonaceae)". Canadian Journal of Chemistry 68, nr 7 (1.07.1990): 1044–50. http://dx.doi.org/10.1139/v90-163.

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The structure of Mezzettiaside 3, a highly acylated trisaccharide obtained from the stem bark of Mezzettialeptopoda, was determined by a combination of double-quantum-filtered {1H,1H} correlation spectroscopy, two-dimensional homonuclear Hartmann–Hahn, and 1H-detected {1H,13C} one-bond and multiple-bond shift correlation nuclear magnetic resonance experiments, in conjunction with fast-atom-bombardment mass spectrometry. Mezzettiaside 3 was found to be the α-(n-octyl)glycoside of 3,4-di-O-acetyl-L-rhamnopyranosyl-α(1 → 3)-2,4-di-O-acetyl-L-rhamnopyranosyl-α(1 → 3)-4-O-hexanoyl-L-rhamnopyranose. The heteronuclear multiple-bond correlation NMR technique proved to be invaluable in establishing the location of the O-acyl groups in this complex carbohydrate. Keywords: oligosaccharide, HMBC, HMQC, HOHAHA, FAB-MS.

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48

Tachikawa, Hiroto. "SN2 and SN2′ reaction dynamics of cyclopropenyl chloride with halide ion A direct ab initio molecular dynamics (MD) study". Canadian Journal of Chemistry 83, nr 9 (1.09.2005): 1597–605. http://dx.doi.org/10.1139/v05-176.

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Direct ab initio molecular dynamics (MD) calculations have been carried out for the reaction of cyclopropenyl chloride with halide ion (F) (F + (CH)3Cl → F(CH)3 + Cl) in gas phase. Both SN2 and SN2′ channels were found as product channels. These channels are strongly dependent on the collision angle of F to the target (CH)3Cl molecule. The collision at one of the carbon atoms of the C=C double bond leads to the SN2′ reaction channel; whereas the collision at the methylene carbon atom leads to the SN2 reaction channel. The reactions proceed via a direct mechanism without long-lived complexes. The reaction mechanism is discussed on the basis of the theoretical results.Key words: SN2 reaction, direct ab initio molecular dynamics, halogen exchange, reaction mechanism.

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49

Andrada, Diego M., Nicole Holzmann i Gernot Frenking. "Bonding analysis of ylidone complexes EL2 (E = C–Pb) with phosphine and carbene ligands L". Canadian Journal of Chemistry 94, nr 12 (grudzień 2016): 1006–14. http://dx.doi.org/10.1139/cjc-2016-0263.

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Quantum chemical calculations using DFT and ab initio methods have been carried out of the compounds EL2 with atoms E = C–Pb and the ligands L = PPh3, N-heterocyclic carbene (NHC), bicyclic NHC, and cyclic alkyl-amino carbene (cAAC). The equilibrium structures are reported and the bonding situation was analyzed with a variety of charge- and energy decomposition methods. Some of the molecules are experimentally known, but most molecules have not yet been prepared. The bonding analysis suggests that all but one molecule should be considered as ylidones that possess dative bonds L→E←L. The sole exception is C(cAAC)2, which has a linear structure and classical double bonds (cAAC)=C=(cAAC). The ylidones EL2 have two lone-pair orbitals at atom E with σ and π symmetry. The π lone pair is somewhat delocalized due to L←E→L π-backdonation. The contribution of L←E→L π-backdonation relative to L→E←L σ-donation increases for the heavier elements. The compounds have rather large first and second proton affinities, which is a characteristic feature of ylidones. They are thus double Lewis bases that could be utilized in chemical reactions.

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50

Zhang, Jingfang, Jieyu Liu, Lifei Xi, Yifu Yu, Ning Chen, Shuhui Sun, Weichao Wang, Kathrin M. Lange i Bin Zhang. "Single-Atom Au/NiFe Layered Double Hydroxide Electrocatalyst: Probing the Origin of Activity for Oxygen Evolution Reaction". Journal of the American Chemical Society 140, nr 11 (8.03.2018): 3876–79. http://dx.doi.org/10.1021/jacs.8b00752.

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