Transformation Reactions Research Articles

Catalytic Activity of Incorporated Palladium Nanoparticles on Recycled Carbon Black from Scrap Tires.

A stable support substrate for catalytically active metal nanoparticles (NPs) plays an important role in various chemical transformation reactions. This study describes the effective integration of catalytically active palladium nanoparticles (PdNPs) into recycled carbon black (rCB) obtained from scrap tires. The loading efficiency and dispersion degree of PdNPs prepared via a deposition-precipitation method are thoroughly compared to those prepared with conventional Vulcan CB. As the rCB powder exhibits relatively larger surface areas and wider pore size distributions, slightly polydisperse and more PdNPs are integrated across rCB than those on CB. These composite materials are subsequently tested as catalysts in the Suzuki coupling and styrene hydrogenation reactions. For the Suzuki reaction using phenylboronic acid and bromobenzene, the PdNPs on rCB exhibit slightly higher reactivity than those on CB (TOF of ∼9/h vs ∼8/h), presumably due to the structural features of the integrated PdNPs and the relatively hydrophobic characteristics of the rCB substrate. For the hydrogenation reaction, both composite materials easily result in over 99% yield under ambient conditions with similar activation energies of ∼32 kcal/mol. These composite materials are also recyclable in both reactions without a detectable loss of the PdNP catalyst and its activity. Understanding the physicochemical properties of rCB and demonstrating their potential use as a catalyst support substrate evidently suggest the possibility of replacing conventional CB, which also provides an idea of upcycling waste tires in the development of practical and green reaction systems.

Pioneering Metal-Free Late-Stage C-H Functionalization Using Acridinium Salt Photocatalysis.

Using organic dyes as photocatalysts is an innovative approach to photocatalytic organic transformations. These dyes offer advantages such as widespread availability, adaptable absorption properties, and diverse chemical structures. Recent progress has led to the development of organic photocatalysts that can utilize visible light to modify chemically inert C-H bonds. These catalysts are sustainable, selective, and versatile, enabling mild reactions, late-stage functionalization, and various transformations in line with green chemistry principles. As catalysts in photoredox chemistry, they contribute to the development of efficient and environmentally friendly synthetic pathways. Acridinium-based organic photocatalysts have proved valuable in late-stage C-H functionalization, enabling transformative reactions under mild conditions. This review emphasizes their innovative features, such as organic frameworks, efficient light absorption properties, and their applications in modifying complex molecules. It provides an overview of recent advancements in the use of acridinium-based organic photocatalysts for late-stage C-H bond functionalization without the need for transition metals, showcasing their potential to expedite the development of new molecules and igniting excitement about the prospects of this research in the field.

Electrosynthesis for the Development of Selective Organic Reactions

The development of efficient and selective reactions play a vital role in chemical synthesis and drug discovery, serving as crucial drivers for advancements in these fields. Electrosynthesis has emerged as a versatile and powerful tool within organic chemistry, enabling the exploration and development of new organic reactions. This state-of-the-art technique harnesses the power of electricity to propel chemical transformations, paving the way for synthetic chemists to create intricate organic molecules. In this presentation, we will showcase notable discoveries from the Malapit Lab, highlighting the innovative application of electrochemistry in the exploration of novel and transformative reactions. Among these groundbreaking findings are a site-selective C–H functionalization reaction and the utilization of organoboron reagents to generate diverse carbon-heteroatom products through radical intermediates. These reactions hold promise for the late-stage functionalization of numerous biologically active compounds, presenting exciting opportunities for drug development and synthesis.

(Invited) The Activation of Alkanes at Electrochemical Interfaces Using Real-Time Control of Potentials: Novel Avenues for Energy Storage and Sustainable Chemical Manufacturing

Producing fuels and chemicals using renewable electricity holds the promise to enable a truly sustainable circular economy based on sustainably produced carriers of electrical energy and sustainably produced chemicals. The science which allows us to link electricity to chemical transformations, electrocatalysis, remains chiefly focused on the electricity-driven transformation of small inorganic molecules such as CO2, H2O, N2, as well as the oxidation and reduction of alcohols. However, comprehensive electrification of society will require electrocatalytic reactions that can promote the central processes that sustain today’s society: alkane transformations. In this presentation, I will show how fundamental understanding of the interfacial processes occurring in electrocatalytic reactions, combined with monolayer-sensitive differential electrochemical mass spectrometry, allows us to independently control the elementary steps (adsorption, transformation, desorption) of complex alkane transformation reactions, allowing for the room-temperature fragmentation of ethane into methane, as well as for enabling the extraction of the chemical energy stored in alkanes in the form of electricity. I will show how we can apply these technologies to expand the reaction scope of electrocatalysis, allowing for novel avenues in energy storage, chemical synthesis and plastics recycling.

Electrocatalytic organic transformation reactions in green chemistry: Exploring nanocrystals and single atom catalysts

Electrocatalytic organic transformation reactions in green chemistry: Exploring nanocrystals and single atom catalysts

Mechanism and Origin of Stereoselectivity of N-Heterocyclic Carbene (NHC)-Catalyzed Transformation Reaction of Benzaldehyde with o-QDM as Key Intermediate: A DFT Study.

N-heterocyclic carbene (NHC)-bound ortho-quinodimethane, served as a nucleophile, has occupied an important position for constructing various all-carbon or heterocyclic compounds and attracted increasing attention for the functionalization of benzylic carbon of aromatic aldehydes, whereas the mechanistic studies on the generation and transformations of dienolate intermediate are rare. In the present study, the mechanism of activation/transformation of aldehyde catalyzed by NHC was theoretically studied using the density functional theory (DFT) method. Based on the calculations, the nucleophilic addition process is the stereoselectivity-determining step with RS-configured product being generated preferentially. Furthermore, non-covalent index (NCI) and atoms-in-molecules (AIM) analyses have been performed to disclose the origin of stereoselectivity, by which the larger number and stronger weak interactions are the key for stabilizing the low-energy transition state and thus leading to the stereoselectivity inducing.

Constructing Functional Radiation-Resistant Thorium Clusters for Catalytic Redox Reactions.

When catalytic reactions are interfered with by radiation sources, thorium clusters are promising as potential catalysts due to their superior radiation resistance. However, there is currently very little research on the design synthesis and catalytic application of radiation-stable thorium clusters. In this work, we have elaborately engineered and fabricated three high-nuclear thorium cluster catalysts denoted as Th12L3-MA12, Th12L3-MA6-BF6, and Th12L3-Fcc12, which did not undergo any significant alterations in their molecular structures and compositions after irradiation with 690 kGy γ-rays. We systematically investigated the photocatalytic/thermocatalytic properties of these radiation-resistant thorium clusters for the first time and found that γ-rays could not alter their catalytic activities. In addition, it was found that ligand engineering could modulate the catalytic activity of thorium clusters, thus expanding the range of catalytic applications of thorium clusters, including reduction reactions (nitroarene reduction) and some oxidation reactions (N-heterocyclic oxidative dehydrogenation and diphenylmethane oxidation). Meanwhile, all of these organic transformation reactions achieved a >80% conversion and nearly 100% product selectivity. Radiation experiments combined with DFT calculations showed that the synergistic catalysis of thorium-oxo core and ligands led to the generation of specific active species (H+, O2•-, or tBuO/tBuOO•) and activation of substrate molecules, thus achieving superior catalytic performance. This work is not only the first to develop radiation-resistant thorium cluster catalysts to perform efficient redox reactions but also provides design ideas for the construction of high-nuclearity thorium clusters under mild conditions.

Co-aromatization of methane and methanol over MoxZn/HZSM-5 to increase aromatic hydrocarbon yield: experimental and kinetic studies

Co-aromatization of methane and methanol over MoxZn/HZSM-5 was conducted to improve hydrocarbon yield and methane conversion. Natural gas, coalbed methane, and coke oven gas are rich in methane. The utilization of methane-rich gas is particularly important as energy demand continues to increase and environmental requirements continue to rise. The efficient conversion to light aromatics is obtained using a co-feed of methane and methanol under relatively mild conditions and catalyzed by MoxZn/HZSM-5. In general, Mo species promote the C-H bond breaking of methane to produce intermediates. Mo is transformed into Mo2C in the co-aromatization reaction as observed by FT-IR and XPS, which leads to the higher activity and aromatic selectivity of the catalyst and can also avoid carbon deposition of the catalyst. Furthermore, kinetic analysis results indicate that olefins play an important role during the co-aromatization of methane and methanol. Olefins are the key reaction intermediates to form aromatics and olefins initially formed in the transformation reaction of methanol perhaps promote the conversion of methane.

RGO@MoS2 as the host-separator modifier with efficient polysulfides trapping and fast Li+ diffusion for lithium-sulfur batteries

Lithium sulfur battery is widely regarded as the most promising next generation energy storage systems because of its high specific energy (2600 Wh kg−1). However，its commercial application is still limited by numerous challenges, including the insulation of charging/discharging products sulfur and Li2S2/Li2S, as well as the "shuttle effect" triggered by the soluble polysulfides. Herein, we report that a functional separator modified by a rGO@MOS2 composites comprising ultrathin MoS2 nanosheets in-situ growth on the surface of reduced graphene oxide (rGO). This composite boasts -an abundant mesoporous structure and large specific surface area can effectively adsorb lithium polysulfides (LiPSs). Additionally, the introduction of high conductive rGO and ultrathin MoS2 nanosheets with rich edge active sites can accelerate the catalytic transformation reaction from LiPSs to Li2S2/Li2S, thus inhibiting the "shuttle effect". In comparison to Li-S batteries without rGO@MoS2 composites, batteries equipped with the functional separator exhibit an impressive initial discharge capacity of 1125.4 mAh g−1 at 1 C, and retain at 910.4 mAh g−1 after 200 cycles, with a low capacity decay rate of 0.09 % per cycle, indicating excellent cyclic stability. Moreover, the areal capacity of the electrode with high sulfur loading mass of 4.1 mg cm−2 is 4.1 mAh cm−2, approaching the practical application standard at a current density of 0.1 C.

Heterogeneous Iron-Based Catalysts for Organic Transformation Reactions: A Brief Overview.

Iron (Fe) is considered to be one of the most significant elements due to its wide applications. Recent years have witnessed a burgeoning interest in Fe catalysis as a sustainable and cost-effective alternative to noble metal catalysis in organic synthesis. The abundance and low toxicity of Fe, coupled with its competitive reactivity and selectivity, underscore its appeal for sustainable synthesis. A lot of catalytic reactions have been performed using heterogeneous catalysts of Fe oxide hybridized with support systems like aluminosilicates, clays, carbonized materials, metal oxides or polymeric matrices. This review provides a comprehensive overview of the latest advancements in Fe-catalyzed organic transformation reactions. Highlighted areas include cross-coupling reactions, C-H activation, asymmetric catalysis, and cascade processes, showcasing the versatility of Fe across a spectrum of synthetic methodologies. Emphasis is placed on mechanistic insights, elucidating the underlying principles governing iron-catalyzed reactions. Challenges and opportunities in the field are discussed, providing a roadmap for future research endeavors. Overall, this review illuminates the transformative potential of Fe catalysis in driving innovation and sustainability in organic chemistry, with implications for drug discovery, materials science, and beyond.

Illitization of montmorillonite in ammonium solutions under hydrothermal conditions

In diagenetic solutions, ammonium may be incorporated into smectites as an exchangeable cation and become fixed within the interlayer space of illites and other white micas. To study the potential impact of NH4+ on the smectite-to-illite transformation reaction, a series of hydrothermal experiments were carried out at 100, 150 and 200 °C, spanning reaction duration from 15 to 90 days, and two NH4+ concentrations (0.1 and 0.2 M). The solids resulting from these alteration experiments were characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and transmission and analytical electron microscopy (TEM and AEM). The XRD analysis revealed that, under the specified experimental conditions, smectite incorporates NH4+ in the structure, leading to the formation of non-swelling layers, resulting in partial transformation to illite layers and producing packets of disordered illite/smectite (I/S). In addition, a minor XRD peak at ∼10 Å suggests the formation of discrete illite crystals. The FTIR spectra demonstrated the uptake of NH4+, with deformation bands observed at 1400 and 1430 cm−1, corresponding to exchangeable NH4+ in smectite and fixed NH4+ in high-charge layers, respectively. TEM analysis revealed that smectite particles exhibited wavy stacks comprising a few layers with abundant defects and lateral discontinuities. The interlayer spacing in these particles ranged from 12 to 15 Å and became thinner and more plate-like with increasing temperature and time. Moreover, they contained inclusions of 10–10.3 Å layers, either as discrete layers or in packets of several layers, indicating the formation of disordered mixed-layer illite-smectite. Lateral transitions from 12 to 15 Å to 10 Å layers were frequently observed and interpreted as reaction fronts due to local rearrangement. At 150 and 200 °C, isolated packets of 10 Å layers were identified as discrete illite crystals that precipitated directly from solution. Analysis of the chemical composition of individual particles revealed an increase in octahedral charge (MgVI for AlVI substitution) in smectite particles, followed by increase in tetrahedral charge in I/S particles. Interlayer NH4+ played a stabilizing role in the high-charge layers and favored the smectite-to-illite conversion process.

Effects of TaB2 addition on microstructure and mechanical properties of Nb[sbnd]Si based alloys

The effects of TaB2 addition on the Nb-16Si-22Ti-3Al alloy were investigated in this study. The results showed that the Nb-16Si-22Ti-3Al alloy consisted of the Nbss phase, α-Nb5Si3 phase, Nb3Si phase, and Tiss phase. With the addition of TaB2 increased from 0 to 0.25 at. %, the Nb3Si disappeared and the eutectic transformation reaction occurred (Nb3Si → Nbss + α-Nb5Si3), which made the volume fraction of the Nbss phase increased from 38.6% to 50.3%. With the TaB2 addition further increasing to 2.0 at. %, the α-Nb5Si3 became the primary phase, and the microstructure transformed from the Nbss + α-Nb5Si3 eutectic structure to the primary α-Nb5Si3 and (Nbss + γ-Nb5Si3) hypereutectic structure. The alloy with 0.25 at. % TaB2 addition had the highest fracture toughness of 10.2 MPa•m1/2 due to the refinement of microstructure and the increment of ductile Nbss. The maximum compressive strength of TaB2 added alloy at room temperature reached 2587.25 MPa in 2.0TaB2 specimen, owing to the solid solution strengthening of Ta and B, and the increment of the silicides content. Additionally, by comparing the fracture toughness of alloys with TaB2 addition obtained by three-point bending (SENBs) and indentation methods, respectively, the feasibility of estimating the fracture toughness of NbSi based alloys by the indentation method is demonstrated with an error of below 20%, which provided a basis for subsequent rapid performance characterization.

INTEGRATED ANALYSIS OF IMMUNOLOGICAL BLOOD PARAMETERS IN PRESCHOOL CHILDREN WITH RECURRENT RESPIRATORY INFECTIONS

Background. Recurrent respiratory infections are a very pressing problem in everyday pediatric practice. They are most commonly diagnosed in preschool children. According to different researchers, their incidence varies considerably (6-30%). The temporary immaturity of immune system is thought to be one of the causes of frequent episodes of acute respiratory infections (ARI). Aim: To determine the state of interdependence between the particular indicators of complex immunological blood test and the frequency of ARI episodes in preschool children. Materials and methods. A total of 26 children (11 boys and 15 girls) aged 1-4 years, undergoing inpatient treatment on ARI, were involved in the clinical study. The number of ARI episodes during the previous year of their life was taken into account. Additionally, two integral indices of ARI recurrence, specifically the infection index and resistance index, were calculated. The children underwent a clinical blood test. Also, the particular indicators of humoral and cellular immunity, functional activity of immune cells (neutrophil phagocytic activity (PhA), lymphocyte blast transformation reaction), complement system (C3c, C4) and the several classes of circulating immune complexes (CIC) were analyzed. The statistical processing of the digital data was performed using IBM SPSS Statistics 28 licensed software with the calculation of the confidence interval (CI) for the main indicators. Results. The prevalent majority of the examined children (80.8%) had an increased serum CIC(small) level. There was a moderate positive correlation between the resistance index values and the CIC(small) level [ρ = 0.392; p = 0.048; CI: 0.072–0.644]. The tightest interdependence was found in the following pairs of studied indicators: 1) CIC(medium)*CIC(small) [ρ=0.732; p<0.001; CI: 0.471–0.875]; 2) C3c*C4 [ρ=0.658; p<0.001; CI: 0.352–0.837]; 3) CIC(large)*Ig(A+M+G) [ρ=0.643; p<0.001; CI: 0.330–0.829]; 4) PhA(spontaneous)*PhA(induced) [ρ=0.601; p=0.001; CI: 0.267–0.806]. A linear regression analysis showed that the predicted resistance index was dependent on only one of the immunological blood parameters considered, specifically total leukocyte antigen. Among other possible predictors, the impact of this antigen on the dependent variable was 18.4%. Conclusions. The particular indicators of a complex immunological blood test are highly interrelated. The results obtained should be taken into account when developing an integrated model for predicting the likelihood of recurrent ARI episodes in preschool children.

Pd-Catalyzed Atroposelective C-H Olefination: Diverse Synthesis of Axially Chiral Biaryl-2-carboxylic Acids.

Axially chiral carboxylic acids are important motifs in chiral catalysts and ligands. We herein reported the synthesis of axially chiral carboxylic acids via Pd(II)-catalyzed atroposelective C-H olefination using carboxylic acid as the native directing group. A broad range of axial chiral biaryl-2-carboxylic acids were synthesized in good yields with high enantioselectivities (up to 84% yield with 99% ee). Gram-scale reaction and further transformation reactions also provide a platform for synthetic applications of this method.

Calcium‐ferrum‐alumina‐silicate (CFAS) corrosion behavior of Lu4Hf3O12 ceramics at 1400°C

AbstractIn this work, the corrosion behavior of rare‐earth Lu4Hf3O12 ceramic when exposed to a CaO‐FeO1.5‐AlO1.5‐SiO2 (CFAS) environment at a temperature of 1400°C was investigated, with a focus on exploring the associated phase transformation, microstructure evolution, and corrosion reaction mechanism. Results reveal that during the corrosion process, the CFAS melt infiltrates Lu4Hf3O12 particles through cracks, resulting in the formation of a continuous reaction layer. This reaction leads to the generation of several high‐melting‐point garnets, including HfO2, Lu3Al5O12, Ca3Fe2(SiO4)3 (Ca‐Fe garnet), and Ca3Al2Si3O12 (Grossular). These garnets effectively fill the voids within the Lu4Hf3O12 ceramics, preventing further infiltration of the CFAS melts. As time progresses, the rate of the reaction gradually increases, while the rate of infiltration consistently decreases. Consequently, a relatively stable corrosion layer is achieved, effectively impeding further corrosion.

Resolving Transformative Reactions in Zeolites under Catalytic Hydrothermal Conditions

Resolving Transformative Reactions in Zeolites under Catalytic Hydrothermal Conditions

Synthesis of sulphone-infused two-dimensional microporous covalent organic frameworks involving Ni(II) porphyrin and sulfur powder for the photocatalytic generation of N-benzylidene benzylamine and their derivatives

In this article, the synthesis of a two-dimensional sulfone-based microporous COF, Ni-P has been executed via C-S coupling of nickel (II) tetra(p-bromophenyl) porphyrin with sulfur powder in the presence of the catalytic amount of CuI and benzotriazole in an inert atmosphere (N2) at 120 °C for 7–8 hrs. The authenticity as well as physiochemical properties of the compound have been investigated using FT-IR, XPS, XRD, TGA, SEM, and BET. The optical band gap (1.9 eV) and electrochemical band gap (2.1 eV) of Ni-P have been calculated through UV–vis and cyclic voltammetric study which finds Ni-P a suitable candidate for photocatalytic study. In the chemical transformation reactions, Ni-P shows an excellent conversion rate of benzylamine for the generation of N-benzylidene benzylamine through oxidative coupling (yield ∼ 99 %). In the photostability study, even after 5 times, it shows good recyclability as evidenced by FT-IR and XRD data.

Constructing surface protective film of V-Se-O to promote zinc ion storage by surface oxygen implantation strategy

Interfacial chemical modification is an effective strategy to adjust the strong Coulombic ion-lattice interactions with high valence cations experienced by electrode materials, facilitating the reaction kinetic. In this paper, a simple and fast surface oxygen implantation strategy was designed to adjust the electronic structure of stainless steel (SS) supported vanadium diselenide (VSe2) nanosheets and form a surface protective film, which effectively accelerates the reaction kinetics of Zn2+ and extends the cycle life of the battery. It is demonstrated that the conductivity, pseudocapacitance and specific capacity can be tuned by selectively introducing oxygen species to the surface, which provides an important reference for the design of electrodes with controlled surface chemistry. Density functional theory (DFT) calculations also confirm that the electronic structure can be adjusted by surface oxygen injection strategy, which not only improves the conductivity, but also adjusts the adsorption energy, thus providing favorable conditions for zinc ion storage. Benefiting from the selenium vacancies and pores generated by the removal of part of selenium, and the oxide film formed on the surfaces, the VSe2-xOx-SS-30 electrode showed higher specific capacity (188.4 mAh/g at 0.5 A g−1 after 50 cycles), better rate performance (107.1 mAh/g at 4 A g−1) and more satisfactory cycling stability (83.1 mAh/g at 5 A g−1 after 1800 cycles) than VSe2-SS electrode. Importantly, the flexible quasi-solid-state VSe2-xOx-SS-30//Zn battery also exhibits high specific capacity and excellent environmental adaptability. Furthermore, the zinc (de)intercalation and transformation reactions mechanism was revealed by some ex-situ/in-situ techniques.

Synthesis of isoprene from 1-butanol and from diethyl ether in the presence of 3d-metal oxides nano-clusters acting as catalysts

The conformational equilibria of 1-butanol (1-BuOH) and diethyl ether (DEE) molecules were investigated in gas and liquid phases. The geometry of the molecules of all stable isomers of 1-BuOH and DEE was fully optimised and the thermochemical quantities’ values (ΔH, ΔG and ΔS) were computed in the temperature range from close to 0 K to 1000 K at the Density Functional Theory (DFT) level. DEE shows two rotamers (namely, Tt and Tg), whereas five different rotamers were identified for 1-BuOH (namely, Tt, Tg, Gt, Gg and Gg’) with different stability, due to the presence of intramolecular interactions. Electrostatic properties of 1-BuOH, ethanol (EtOH), and DEE were also evaluated. Calculated vibration spectra of 1-BuOH and DEE were compared with the experimental FT-IR and Raman spectra recorded in neat phase and diluted in cyclohexane (CHX). The experimental vibrational spectra found the best match with the sum of calculated spectra using the Boltzmann coefficients based on the thermal stability of each conformer. The frequency shift observed for some peaks as a function of the concentration of 1-BuOH in CHX reveals the impact of hydrogen bonds between 1-BuOH molecules, in particular in the case of conformer Gg’. In contrast, very weak interactions among molecules of DEE were spectroscopically detected. The transformation reactions of {1-BuOH+EtOH} and {DEE+EtOH} mixtures at different temperatures were studied using the method of quantum mechanical calculations. The mechanism of isoprene formation from these mixtures was determined taking into account the chemisorption of 1-BuOH and DEE onto metal oxide nano-clusters M4O4 (M = Sc to Zn) and its effect on the vibrations of BuOH and DEE at the interface for M = Zn, Cu and Ti using Raman microscopic spectroscopy.

Imidazolidine‐pyrroloimidazolone Pyridine‐Ni(acac)2 complex Catalyzed Asymmetric Darzens Reaction of Isatins with Phenacyl Chlorides: A Chiral Amplification Effect

With phenacyl chlorides as simple nucleophilic species, the asymmetric Darzens reaction of isatins using Ni(acac)2 as the Lewis acid and imidazolidine‐pyrroloimidazolone pyridine as the ligand is reported. In the presence of 1 mol% of catalyst, diverse spiro‐epoxyoxindoles with two new contiguous stereocenters were afforded in 82‐99% yields, >20:1 dr, and 91‐99% ee. Chiral spiro‐epoxyoxindoles could undergo ring‐opening reactions in further transformations. The developed method was applied to the derivatization of complex molecules including indomethacin, gemfibrozil, and febuxostat‐derived α‐chloroketones. A strong positive nonlinear effect was observed, which was caused by the precipitation of a less‐soluble racemic catalyst complex.