Article
Chemistry, Organic
Jake J. Blackner, Deirdre M. Rooney, Joshua W. Hollett, J. Adam McCubbin
Summary: A boronic acid catalyzed carbon-carbon and carbon-nitrogen bond-forming reaction using ferrocenium boronic acid hexafluoroantimonate salt as catalyst has been developed for the functionalization of various pi-activated alcohols. The reaction proceeds under mild conditions and yields up to 98%, with higher yields and selectivity observed when using organosilane nucleophiles. Computational studies provide a mechanistic pathway for the retention of E/Z stereochemistry when using alkenyl silanes as nucleophiles. This methodology is effective with a variety of organosilane nucleophile sub-types, including allylic, vinylic, and propargylic trimethylsilanes.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Yuki Saito, Shu Kobayashi
Summary: The article discusses the application of chiral heterogeneous Sc catalysts in continuous-flow reactions, achieving efficient synthesis of compounds through noncovalent interactions and the crucial role of heteropoly acid.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Applied
Huimiao Zhang, Patrick H. Toy
Summary: A halogen bond donor based on a 2,2'-bipyridine framework has been synthesized and used to catalyze Friedel-Crafts reactions of furans, yielding good reaction yields with moderate catalyst loading at low temperatures. The catalyst design allows for the potential development of an enantioselective version for stereo-selective catalysis.
ADVANCED SYNTHESIS & CATALYSIS
(2021)
Article
Chemistry, Organic
Haipeng Hu, Xin Wu, Yuqian Qiu, Cuilin Wang, Wei Wang, Guizhou Yue, Hanguang Wang, Juhua Feng, Guangtu Wang, Hailiang Ni, Ping Zou
Summary: In this study, the dehydrative mono-/dialkylation reactions of alcohols and beta-ketoacids were achieved under arylboronic acid catalysis, leading to the formation of beta-aryl ketones and beta-ketoesters in moderate to high yields. The reaction temperature was found to control the selectivity between decarboxylative alkylation and decarboxylation processes. A possible catalytic cycle was proposed based on experimental evidence.
Article
Engineering, Chemical
Yiwen Cao, You Wang, Yuli Fu, Fa Zhou, Jianhan Huang
Summary: Hyper-crosslinked polymers (HCPs) functionalized with 8-hydroxyquinoline (HQ) were successfully fabricated by nucleophilic substitution and Friedel-Crafts alkylation. These polymers showed high adsorption capacity for 2-naphthol, exceeding the discharge standard in China.
SEPARATION AND PURIFICATION TECHNOLOGY
(2023)
Article
Chemistry, Organic
Rekha, Sonam Sharma, Ramasamy Vijaya Anand
Summary: In this study, a simple, efficient, additive-free redox-neutral approach for the synthesis of indolyl diarylmethanes was achieved via a radical reaction of indoles with para-quinone methides (p-QMs) under visible-light mediated reaction conditions using eosin Y as an organophotoredox catalyst. This protocol showed excellent applicability to various substituted p-QMs and indoles, providing the desired products in good to excellent yields in both organic and aqueous media under visible-light irradiation.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2023)
Article
Chemistry, Applied
Hajar Jamali, Reza Teimuri-Mofrad
Summary: The synthesis of new ferrocene-based esters was conducted through alkylation of carboxylic acids with potassium carbonate as a base. 4-iodobutylferrocene was identified as the most effective initial reagent, leading to acceptable reaction yields without catalysts at room temperature. The cyclic voltammetry results demonstrated the potential electrochemical applications of the synthesized esters.
APPLIED ORGANOMETALLIC CHEMISTRY
(2022)
Article
Chemistry, Multidisciplinary
Leijie Zhou, Stefania Perulli, Marco M. Mastandrea, Patricia Llanes, Junshan Lai, Miquel A. Pericas
Summary: A polystyrene-supported version of the Denton catalyst has been developed for catalytic inversion of enantiopure secondary alcohols, showing high yields and enantioselectivity. The functional resin exhibits excellent recyclability and can be easily re-activated for extended use.
Article
Engineering, Chemical
Guangfei Feng, Mei Yang, Hongbiao Chen, Bei Liu, Yijiang Liu, Huaming Li
Summary: Novel triazine-linked triphenylimidazole (TPIM) and triphenylimidazolium (TPIM-IL) monomers were synthesized and used to form PTPIM and PTPIM-IL networks via Friedel-Crafts alkylation reaction. The resulting networks exhibited high specific surface areas and PTPIM network could be easily transformed into PTPIM-IL network through post-modification. PTPIM-IL network showed high CO2 uptake capacity and excellent catalytic activity for the cycloaddition of CO2 to epoxides.
SEPARATION AND PURIFICATION TECHNOLOGY
(2023)
Article
Chemistry, Organic
Amjad Ali, Raveena Jajoria, Harish K. Harit, Ravi P. Singh
Summary: In this study, the addition of alpha-ketoamide top-quinone methide initiated by dialkylphosphite in the presence of organic base DBU was explored. The coupling of dialkylphosphites to alpha-ketoamides followed[1,2]-phospha-Brook rearrangement, generating alpha-phosphonyloxy enolates that were subsequently seized by p-quinonemethides. This two-step one-pot 1,6-conjugate addition method provides effective access to a series of isatin-incorporated phosphate-bearing 1,6-adducts with high yield and selectivity.
JOURNAL OF ORGANIC CHEMISTRY
(2022)
Article
Biochemistry & Molecular Biology
Ivan A. Shershnev, Irina A. Boyarskaya, Aleksander V. Vasilyev
Summary: By studying the reaction mechanism of 5,5,5-trichloropent-3-en-2-one in Bronsted superacid CF3SO3H, it was found that a novel class of indene derivatives can be formed.
Review
Biochemistry & Molecular Biology
Michal Barbasiewicz, Michal Fedorynski, Rafal Loska, Mieczyslaw Makosza
Summary: The aim of this essay is to reveal the similarity in a wide range of reactions between nucleophiles and p-electrophiles, regardless of whether they are aromatic or aliphatic. These reactions involve reversible addition followed by various transformations, common for both aliphatic and aromatic electrophile adducts. The understanding of this analogy is expected to broaden the scope of known reactions and inspire the exploration of new reactions that have been overlooked.
Article
Chemistry, Multidisciplinary
Fei Wang, Yoshihiro Nishimoto, Makoto Yasuda
Summary: The study reports a new method catalyzed by BF3 for carbon elongation of benzylic fluorides. Through DFT calculation study, it was found that the BF3 catalyst could contribute to both C-F bond cleavage and re-formation. This method shows high diastereoselectivity and can be applied to various benzylic fluorides and diazo esters for synthesis.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2021)
Article
Chemistry, Multidisciplinary
Nicolas Zeidan, Sergiu Bicic, Robert J. Mayer, David Leboeuf, Joseph Moran
Summary: This study demonstrates that HFIP greatly expands the scope of the Bronsted acid-catalyzed hydroarylation of enamides, and acts as a slow-release reservoir for the key cationic intermediate. The reaction is fast and practical, and can prevent the oligomerization of the substrate.
Review
Chemistry, Multidisciplinary
Takanori Iwasaki, Nobuaki Kambe
Summary: Carbon-fluorine bonds are stable but can be selectively transformed under appropriate conditions, making them useful synthetic methods in organic chemistry. This review focuses on C-C bond formation at monofluorinated sp(3)-hybridized carbons via C-F bond cleavage, including cross-coupling and multi-component coupling reactions. The mechanisms of C-F bond cleavage on sp(3)-hybridized carbon centers are categorized into three types: Lewis acids promoted F atom elimination, nucleophilic substitution with metal or carbon nucleophiles, and cleavage of C-F bonds via single electron transfer. Furthermore, the unique characteristics of alkyl fluorides compared to other (pseudo)halides as electrophilic coupling counterparts are discussed.
Article
Materials Science, Multidisciplinary
S. Mungiguerra, L. Silvestroni, R. Savino, L. Zoli, B. Esser, M. Lagos, D. Sciti
Summary: Qualification and reusability campaigns were conducted on ultra-high temperature ceramic matrix composites to evaluate their performance as thermal protection systems. The new composites showed increased erosion resistance and preserved structural stability even under high thermal loads.
Article
Engineering, Manufacturing
Antonio Vinci, Laura Silvestroni, Nicola Gilli, Luca Zoli, Diletta Sciti
Summary: This study investigates the effects of rare earth oxides on carbon fibre-ZrB2/SiC composites and finds that the addition of Y2O3, La2O3, and CeO2 improves the densification of the material, while Sc2O3 promotes the formation of solid solutions in the matrix. All the composites exhibit improved mechanical properties, but CeO2 is detrimental to the long-term structural stability.
COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING
(2022)
Article
Engineering, Multidisciplinary
D. Sciti, L. Zoli, T. Reimer, A. Vinci, P. Galizia
Summary: This paper presents a systematic approach to scale up the Ultra-High Temperature Ceramic Matrix Composites (UHTCMCs) based on carbon fiber reinforced zirconium diboride plus silicon carbide. The scale-up process lasted for three years, resulting in an increase in diameter by 10 times and thickness by 30 times. By utilizing hot pressing and spark plasma sintering techniques, the composites with different dimensions were successfully consolidated with good reproducibility.
COMPOSITES PART B-ENGINEERING
(2022)
Article
Materials Science, Ceramics
Francesca Servadei, Luca Zoli, Pietro Galizia, Cesare Melandri, Diletta Sciti
Summary: Carbon fibre reinforced ultra-high temperature ceramic (UHTC) matrix composites were fabricated using different consolidation techniques, and it was found that the second technique resulted in composites with higher flexural strength.
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
(2022)
Article
Materials Science, Ceramics
Francesca Servadei, Luca Zoli, Pietro Galizia, Andreana Piancastelli, Diletta Sciti
Summary: Uncoated PAN-based carbon fibre-reinforced ultra-high temperature ceramic matrix composites were manufactured using aqueous ZrB2 powder-based slurry impregnation, mild polymer infiltration, and pyrolysis with allylhydrido polycarbosilane. Different cloth architectures, including unidirectional (UD), two-dimensional (2D), and needle-punched (2.5D), were impregnated to demonstrate the versatility of the process. The microstructure and mechanical properties were studied and correlated with fiber properties and architecture. The process resulted in a homogeneous distribution of UHTC phase around each fiber and a weak fiber/matrix interface, leading to improved durability and performance in extreme environments without the need for expensive fiber coating.
CERAMICS INTERNATIONAL
(2023)
Article
Materials Science, Ceramics
Antonio Vinci, Luca Zoli, Laura Silvestroni, Nicola Gilli, Diletta Sciti
Summary: A significant improvement in mechanical performance was achieved in ZrB2-based ultra-high temperature ceramic matrix composites (UHTCMCs) through the introduction of rare earth oxides, resulting in the formation of ternary boro-carbides of general formula REB2C2. This study investigated the potential routes for synthesizing YB2C2 phases at UHTC sintering temperatures by using different boron sources, and analyzed their microstructure using SEM, XRD, and TEM. The findings showed that the mixture with B4C exhibited the highest selectivity for the formation of YB2C2, and a long carbon fibre reinforced YB2C2 ceramic composite with a flexural strength of 380 MPa was successfully fabricated. The chemical stability of these materials in air was also assessed.
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
(2023)
Article
Materials Science, Ceramics
Francesca Servadei, Luca Zoli, Pietro Galizia, Cesare Melandri, Simone Failla, Diletta Sciti
Summary: Cf/ZrB2-SiC composites were prepared by water-based slurry impregnation followed by polymer infiltration and pyrolysis. The composite showed a flexural strength above 500 MPa at temperatures up to 1400 degrees C. Thermal treatments between 1400 degrees C and 1900 degrees C led to microstructural changes and affected the flexural strength. Annealing at 1400 degrees C resulted in a decrease in strength at room temperature due to the creation of new porosity, but maintained the strength up to 87% at 1500 degrees C. Annealing at higher temperatures had a detrimental effect on microstructure and strength.
CERAMICS INTERNATIONAL
(2023)
Article
Chemistry, Physical
Elena Bassan, Francesco Calogero, Yasi Dai, Angela Dellai, Alessandro Franceschinis, Emanuele Pinosa, Fabrizia Negri, Andrea Gualandi, Paola Ceroni, Pier Giorgio Cozzi
Summary: A new meso-naphthalenyl BODIPY was developed to efficiently generate long-lived triplet excited state when exposed to green light. This heavy atom-free organic chromophore was used in a dual palladium and photoredox catalysis, demonstrating the applications of BODIPY dyes as photoredox catalysts.
Article
Chemistry, Multidisciplinary
V. Barone, M. Fuse, R. Aguado, S. Potenti, I. Leon, E. R. Alonso, S. Mata, F. Lazzari, G. Mancini, L. Spada, A. Gualandi, P. G. Cozzi, C. Puzzarini, J. L. Alonso
Summary: A study was conducted on 4-fluoro-threonine, the only naturally occurring fluorinated amino acid, combining experimental and theoretical approaches. The conformational landscape of this amino acid was extensively characterized, leading to the identification of 13 stable low-energy minima. Through a combination of quantum chemical calculations and machine learning principles, the complex rotational spectrum of this molecule could be assigned, and 12 out of 13 conformers were experimentally confirmed. The results obtained from analyzing intra-molecular interactions can be used to model fluorine-substitution effects in biomolecules accurately.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Organic
Emanuele Pinosa, Elena Bassan, Sultan Cetin, Marco Villa, Simone Potenti, Francesco Calogero, Andrea Gualandi, Andrea Fermi, Paola Ceroni, Pier Giorgio Cozzi
Summary: The stability of a TADF photocatalyst was investigated and found that it can be efficiently converted into another species under visible light irradiation in the absence of quenchers. The new species obtained has useful applications in photoredox transformations.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Materials Science, Ceramics
Matteo Mor, Antonio Vinci, Simone Failla, Pietro Galizia, Luca Zoli, Diletta Sciti
Summary: A new technique for manufacturing short fibre-reinforced ultra-refractory ceramics is introduced. It allows the production of solvent-free, thin, flexible, and easy-to-handle sheets suitable for various structures. The composition range can be adjusted from 0% to 100%. By increasing the fibre amount, the mechanical properties of the ceramics showed improvement. Functionally graded composites were also successfully fabricated using this technique.
JOURNAL OF ADVANCED CERAMICS
(2023)
Article
Engineering, Mechanical
T. Reimer, G. D. Di Martino, D. Sciti, L. Zoli, P. Galizia, A. Vinci, M. A. Lagos, N. Azurmendi
Summary: The development of new Ultra High-Temperature Ceramic Matrix Composites (UHTCMC) for use in severe space applications lacks sufficient data regarding the properties influencing structural behavior. This study proposes and applies two different methodologies to investigate the fatigue life of UHTCMCs based on ZrB2-SiC, resulting in the determination of their sigma/N curves.
INTERNATIONAL JOURNAL OF FATIGUE
(2023)
Article
Chemistry, Physical
Laura Silvestroni, Antonio Vinci, Nicola Gilli, Luca Zoli, Diletta Sciti, Dietmar Koch, Marius Kuetemeyer
Summary: The reactions between a Zr2Cu melting phase and compounds for ultra-refractory ceramic matrix composites, including SiC, TiB2, and ZrB2, were investigated. The results confirmed the good infiltration capability of the melt. A multiphasic ultra-high temperature ceramic matrix composite was prepared through reactive melt infiltration (RMI) using a TiB2-coated carbon fiber preform infiltrated with Zr2Cu. A second composite was prepared by introducing an additional ZrB2-B infiltration step to reduce the processing temperature and limit fiber damage. The combination of factors on multiple length scales provides synergistic reinforcing phenomena for developing materials for extreme environments.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Materials Science, Ceramics
Diletta Sciti, Antonio Vinci, Luca Zoli, Pietro Galizia, Simone Failla, Stefano Mungiguerra, Giuseppe D. Di Martino, Anselmo Cecere, Raffaele Savino
Summary: Ultra-high-temperature ceramic matrix composites (UHTCMCs) based on a ZrB2/SiC matrix were used to fabricate reusable nozzles for propulsion. The prototypes, obtained by sintering with either hot pressing or spark plasma sintering, were tested multiple times without observable erosion. The oxidation mechanism involved the formation of a ZrO2 intermediate layer and a silicon oxide (SiO2) layer on the surface, protecting the nozzle from further oxidation.
JOURNAL OF ADVANCED CERAMICS
(2023)
Article
Materials Science, Ceramics
Pietro Galizia, Diletta Sciti, Jon Binner, Vinothini Venkatachalam, Miguel. A. Lagos, Francesca Servadei, Antonio Vinci, Luca Zoli, Thomas Reimer
Summary: This paper presents a comparison study on the microstructures and mechanical properties of different ZrB2-based CMCs produced through different processes. Tensile testing and flexural testing were conducted to assess the structural properties, and for the first time, tensile tests up to 1600 degrees C were performed on UHTCMCs. Despite variations in microstructure, all the ZrB2-based CMCs demonstrated excellent structural properties, even at high temperatures. The study also highlights the influence of porosity and fiber properties on the mechanical behavior of these composites, and discusses the role of residual thermal stresses.
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
(2023)
