| 1. |
- Binbin, Song, et al.
(author)
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Oxidation properties of self-propagating high temperature synthesized niobium disilicide
- 2014
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In: Corrosion Science. - : Elsevier BV. - 0010-938X .- 1879-0496. ; 85, s. 311-317
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Journal article (peer-reviewed)abstract
- NbSi2 monoliths were prepared by self-propagating high temperature synthesis (SHS) and hot pressing (HP) and their oxidation behavior was investigated at various temperatures (823-1123 K) in air. The combustion mode of SHS reaction was steady state combustion, and the combustion product was single-phase NbSi2. Oxidation studies show that the highest mass gain was 0.95675 kg m(-2) at 1023 K. In cyclic oxidation, the oxidation rate was reduced and the mass gain was only 0.15507 kg m(-2). A dense protective amorphous SiO2 scale formed at 823 K and 923 K whereas a porous multilayer SiO2 and alpha/beta-Nb2O5 oxide scales formed at and above 1023 K and spalled off. Pest oxidation of NbSi2 monoliths was not observed in hot pressed NbSi2 monoliths.
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| 2. |
- Lai, Elisa Y., et al.
(author)
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Ruthenium-Catalyzed Aminocarbonylation with Isocyanates Through Weak Coordinating Groups
- 2023
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In: Chemistry - A European Journal. - 0947-6539 .- 1521-3765. ; 29:61
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Journal article (peer-reviewed)abstract
- Introducing amide functional groups under mild conditions has growing importance owing to the prevalence of such moiety in biologically active molecules. Herein, we disclose a mild protocol for the directed ruthenium-catalyzed C−H aminocarbonylation with isocyanates as the amidating agents developed through high-throughput experimentation (HTE). The redox-neutral and base-free reaction is guided by weakly Lewis basic functional groups, including anilides, lactams and carbamates to access anthranilamide derivatives. The synthetic utility of this transformation is reflected by large-scale synthesis and late-stage functionalization.
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| 3. |
- Lin, Zhipeng, et al.
(author)
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Electrocatalyzed direct arene alkenylations without directing groups for selective late-stage drug diversification
- 2023
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In: Nature Communications. - 2041-1723. ; 14:1
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Journal article (peer-reviewed)abstract
- Electrochemistry has emerged as an increasingly viable tool in molecular synthesis. Here the authors realize electrocatalyzed C-H activations, with the aid of data science and artificial intelligence, towards selective alkenylations for late-stage drug diversifications. Electrooxidation has emerged as an increasingly viable platform in molecular syntheses that can avoid stoichiometric chemical redox agents. Despite major progress in electrochemical C-H activations, these arene functionalizations generally require directing groups to enable the C-H activation. The installation and removal of these directing groups call for additional synthesis steps, which jeopardizes the inherent efficacy of the electrochemical C-H activation approach, leading to undesired waste with reduced step and atom economy. In sharp contrast, herein we present palladium-electrochemical C-H olefinations of simple arenes devoid of exogenous directing groups. The robust electrocatalysis protocol proved amenable to a wide range of both electron-rich and electron-deficient arenes under exceedingly mild reaction conditions, avoiding chemical oxidants. This study points to an interesting approach of two electrochemical transformations for the success of outstanding levels of position-selectivities in direct olefinations of electron-rich anisoles. A physical organic parameter-based machine learning model was developed to predict position-selectivity in electrochemical C-H olefinations. Furthermore, late-stage functionalizations set the stage for the direct C-H olefinations of structurally complex pharmaceutically relevant compounds, thereby avoiding protection and directing group manipulations.
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| 4. |
- Ran, Huashen, et al.
(author)
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Microstructure and properties of Ti5Si3-based porous intermetallic compounds fabricated via combustion synthesis
- 2014
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In: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388 .- 1873-4669. ; 612, s. 337-342
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Journal article (peer-reviewed)abstract
- Porous titanium silicides (Ti5Si3-based) were produced by combustion synthesis process from reaction mixtures of titanium to silicon in varying molar ratios. The effects of combustion characteristics of the reaction mixtures on the phase formation, microstructure, porosity, pore size and compressive strength of porous titanium silicide intermetallic compounds were investigated. The results showed that the flame-front propagation velocity and temperature of the combustion reaction were the maximum for the reaction mixture containing Ti and Si in the ratio of 5 to 3 (Ti5Si3), 32.7 mm/s and 2205 K, respectively. X-ray diffraction analysis confirmed that the dominant phase formed was Ti5Si3 in all combustion synthesized porous intermetallic compounds. Ti5Si3-based intermetallic compounds were highly porous. The porosity and pore size of these intermetallics were dependent on the initial composition of the reaction mixture. The total and open porosities of Ti5Si3-based intermetallics varied from 33 to 61% and 17 to 55%, respectively. The porous titanium silicide intermetallic materials displayed high mechanical strength, in the range of 6-35 MPa, duly required for their use as filters.
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