Atmospheric Chemistry Research Articles

Halogen Radical-Enabled Dearomatization of N-Arylpropiolamides via Photoinduced Sequential Halogenation/Spirocyclization/Oxidation Process.

Here we report a strategy that eliminates the need for photocatalysts and external additives, which provides an operable and mild method for halogen radical-enabled dearomatization of N-arylpropiolamides under an oxygen atmosphere at room temperature. The method is applicable to a wide range of substrates, extending beyond the limited scope of p-methoxyl N-phenylpropynamides. Furthermore, several functional synthetic intermediates and anticancer bioactive molecules were successfully derived from 3-halogenated azaspiro[4.5]trienones.

Dual Role of Aerosols on Reactive Bromine Recycling in Extrapolar Marine and Continental Regions

AbstractReactive bromine species play important roles in atmospheric chemistry and influence the abundance of climate‐ and air quality‐relevant trace gases. While extensive studies have focused on bromine chemistry in polar regions, the bromine species in extrapolar regions, particularly regarding pollution‐related bromine recycling, have received less attention. In this study, we examine the factors influencing the bromine recycling at a clean marine site of the North Atlantic (Cape Verde, CVAO), a semipolluted coastal site of the South China Sea (Hok Tsui, HT), and a polluted continental site of North China (Wangdu, WD), using an observation‐based model combined with updated halogen chemistry. Our results indicate that aerosol‐related multiphase processes significantly affect bromine recycling in these extrapolar sites. Nitrate photodissociation efficiently recycled bromide into the gas phase in regions characterized by strong aerosol acidity (HT) or high aerosol concentrations (WD). Concurrently, bromine species are lost from the gas phase toward aerosol surfaces, with this process being more effective at higher liquid water content (WD > HT > CVAO). In semipolluted and polluted sites, the aerosol‐related processes resulted in elevated bromine levels in the daytime compared to nighttime, leading to larger effects of bromine species on ozone than previously thought. Our study suggests the need for a better understanding of the complex effects of aerosols on reactive halogen chemistry.

Viscosity of aqueous ammonium nitrate–organic particles: equilibrium partitioning may be a reasonable assumption for most tropospheric conditions

Abstract. The viscosity of aerosol particles determines the critical mixing time of gas–particle partitioning of volatile compounds in the atmosphere. The partitioning of the semi-volatile ammonium nitrate (NH4NO3) might alter the viscosity of highly viscous secondary organic aerosol particles during their lifetimes. In contrast to the viscosity of organic particles, data on the viscosity of internally mixed inorganic–organic aerosol particles are scarce. We determined the viscosity of an aqueous ternary inorganic–organic system consisting of NH4NO3 and a proxy compound for a highly viscous organic, sucrose. Three techniques were applied to cover the atmospherically relevant humidity range: viscometry, fluorescence recovery after photobleaching, and the poke-flow technique. We show that the viscosity of NH4NO3–sucrose–H2O with an organic to inorganic dry mass ratio of 4:1 is 4 orders of magnitude lower than the viscosity of the aqueous sucrose under low-humidity conditions (30 % relative humidity (RH), 293 K). By comparing viscosity predictions of mixing rules with those of the Aerosol Inorganic–Organic Mixtures Functional groups Activity Coefficients Viscosity (AIOMFAC-VISC) model, we found that a mixing rule based on mole fractions performs similarly when data from corresponding binary aqueous subsystems are available. Applying this mixing rule, we estimated the characteristic internal mixing time of aerosol particles, indicating significantly faster mixing for inorganic–organic mixtures compared to electrolyte-free particles, especially at lower RH. Hence, the assumption in global atmospheric chemistry models of quasi-instantaneous equilibrium gas–particle partitioning is reasonable for internally mixed single-phase particles containing dissolved electrolytes (but not necessarily for phase-separated particles), for most conditions in the planetary boundary layer. Further data are needed to see whether this assumption holds for the entire troposphere at midlatitudes and at RH > 35 %.

Opinion: Challenges and needs of tropospheric chemical mechanism development

Abstract. Chemical mechanisms form the core of atmospheric models to describe degradation pathways of pollutants and ultimately inform air quality and climate policymakers and other stakeholders. The accuracy of chemical mechanisms relies on the quality of their input data, which originate from experimental (laboratory, field, chamber) and theoretical (quantum chemistry, theoretical kinetics, machine learning) studies. The development of robust mechanisms requires rigorous and transparent procedures for data collection, mechanism construction and evaluation and the creation of reduced or operationally defined mechanisms. Developments in analytical techniques have led to a large number of identified chemical species in the atmospheric multiphase system that have proved invaluable for our understanding of atmospheric chemistry. At the same time, advances in software and machine learning tools have enabled automated mechanism generation. We discuss strategies for mechanism development, applying empirical or mechanistic approaches. We show the general workflows, how either approach can lead to robust mechanisms and that the two approaches complement each other, resulting in reliable predictions. Current challenges are discussed related to global change, including shifts in emission scenarios that result in new chemical regimes (e.g., low-NO scenarios, wildfires, mega- and gigacities) and that require the development of new or expanded gas- and aqueous-phase mechanisms. In addition, new mechanisms should be developed to also target oxidation capacity and aerosol chemistry impacting climate, human and ecosystem health.

Development of the CMA-ChemRA: China Regional Weakly Coupled Chemical-Weather Reanalysis System with product since 2007.

The CMA-ChemRA (China Regional Weakly Coupled Chemical-Weather Reanalysis System) was developped using China's first-generation global atmospheric reanalysis product (CRA-40) as initial fields and boundary conditions, coupled with the WRF-Chem atmospheric chemical model and the WRFDA/3DVar assimilation system. By constructing a joint background error covariance matrix, CMA-ChemRA achieves weak coupling between atmospheric chemistry and meteorological variables, enabling simultaneous assimilation of diverse data sources, including hourly observations from ground stations, wind profilers, upper-air soundings, aircraft reports, and atmospheric composition measurements. To extend the dataset to periods before 2013 when China lacked PM2.5 observations, the system incorporates a reconstructed PM2.5 dataset derived by AI from visibility inversion alongside various emission inventories. The CMA-ChemRA system produces a reanalysis product from 2007 to the present, with a spatial resolution of 15km and an hourly temporal resolution. It includes three-dimensional isobaric and near-surface layers for 6 key elements PM2.5, PM10, O3, SO2, NO2, and CO, as well as meteorological variables. This product is updated in near real-time, with a 50-min lag for forecast updates. Evaluation of the system shows substantial improvements in accuracy, with significant reductions in root mean square error (RMSE) for the six elements in the near-surface atmospheric layer post-assimilation. The model's depiction of ground-level PM2.5 concentrations aligns well with independent observational data across five urban regions, showing a narrow RMSE range of 15.5 to 32.8μg/m3. Additionally, CMA-ChemRA demonstrates strong performance in capturing the evolution of dust storms and pollution events, particularly in accurately modeling PM2.5 concentrations during severe pollution episodes. Our innovative approach in constructing a joint background error covariance matrix and the resulting high-resolution, real-time updating CMA-ChemRA product. This represents significant advancement in the field of atmospheric and chemical weather reanalysis. The product serves as an crucial tool for environmental monitoring and forecasting in China.

Ciprofloxacin degradation over Co3O4 catalysts by the microwave-assisted persulfate oxidation: a critical role of coordination composition

The combination of catalysts and microwave (MW) effects presents an emerging approach for persulfate (PS) activation, while the effect of active sites of catalysts on the synergistic reaction remains poorly understood. Here, we regulated the coordination composition of Co3O4 by strategically controlling the oxygen atmosphere during fabrication. We found that Co3+ and Co2+ acted as reactive centers for microwave absorption and catalytic activation of persulfate, respectively. By altering the ratio between Co3+ and Co2+, we explored the Co3O4 (2.23)-550 catalysts with significantly improved synergistic activity for degrading ciprofloxacin (CIP), which was 33.0 and 26.8 times higher than PS- Co3O4 (2.23)-550 (without microwave) and MW- Co3O4 (2.23)-550 (without persulfate), respectively. Meanwhile, Co3O4 (2.23)-550 catalyst (0.5mgL-1) showed the highest degradation rate of CIP 92.6% (0.5mgL-1) within 10min under microwave. According to the radical identification and intermediate analysis, the efficient degradation of CIP was ascribed to both free radical and non-free radical pathways. Thus, this work raises new insights into the structure-activity relationship of catalysts, and provides an efficient way to eliminate antibiotics via synergistic catalysis.

History of Atmospheric Chemistry in Switzerland.

This paper presents an overview on atmospheric chemistry, beginning with international aspects since the Roman Empire, and then focusing on the developments in Switzerland. Finally, the institutions dealing with atmospheric chemistry along with relevant scientists are briefly described.

Secondary Organic Aerosol from Biomass Burning Phenolic Compounds and Nitrate Radicals can be Highly Viscous over a Wide Relative Humidity Range.

Biomass burning events, including wildfires, can emit large amounts of phenolic compounds such as guaiacol. These phenolic compounds can undergo oxidation by nitrate radicals (NO3) to form secondary organic aerosol (SOA). Viscosity and hygroscopicity are key properties that affect SOA's role in atmospheric chemistry, air quality, climate and public health. However, these properties have not been quantified for SOA formed from the reaction of phenolic compounds with NO3. We used the poke-flow technique and a quartz crystal microbalance (QCM) to measure the viscosity and hygroscopicity of SOA particles generated from the reaction of NO3 with guaiacol, termed guaiacol-NO3 SOA. The viscosity of this SOA is extremely high (≳5 × 107 Pa s) at RH ≲ 70% and drastically higher than other SOA types previously investigated with the poke-flow technique at RH ≳ 40%. The high viscosity for guaiacol-NO3 SOA can be attributed, at least in part, to the low hygroscopicity measured via the QCM. From the viscosity results, we calculated the mixing times of organic molecules within guaiacol-NO3 SOA. The results suggest that mixing times within this type of SOA exceed 1 h for most tropospheric conditions, with possible implications for predicting the size, mass, and long-range transport of pollutants in phenolic SOA.

Ammonia Emissions from Swiss Agriculture and their Effects on Atmospheric Chemistry and Ecosystems

Ammonia (NH3) is an important atmospheric pollutant due to its contribution to secondary inorganic aerosol formation and its deposition and impacts on (semi-)natural ecosystems. Therefore various efforts have been made to limit emissions to the atmosphere. The predominant emission source in Switzerland is livestock agriculture, wherein NH3 is volatilised from ammonium contained in animal manure. While modelled NH3 emissions based on agricultural activity data indicate a minor decrease since 2000, concentration measurements do not reflect this trend. This can at least partly be attributed to a decline in the transformation of NH3 to particulate ammonium due to significantly decreased emission of oxidised nitrogen and sulfur compounds in the past decade. The partitioning between the gaseous and the particulate phase also determines the deposition pathway (dry or wet deposition) and thus the average lifetime and transport distance in the atmosphere. Gaseous NH3 is subject to fast dry deposition and is deposited preferentially to ecosystems close to the source. Once deposited into an ecosystem, NH3 leads to eutrophication and acidification of water and soils, which change the plant community composition and microbial functioning, especially in N-sensitive ecosystems. Although NH3 can also cause direct toxicity to plants, assessments of ecosystem impacts are generally collated using the critical load approach, which includes the input of all N compounds. These reveal that in 2020, 87% of forests, 94% of raised bogs, 74% of fens, and 42% of dry mountain grasslands likely experienced adverse impacts from N exceedances in Switzerland. To improve this situation, considerable NH3 emission abatement efforts are needed in the future.

The influence of pH on the liquid-phase transformation of phenolic compounds driven by nitrite photolysis: Implications for characteristics, products and cytotoxicity

The aqueous-phase conversion of phenolic compounds (PhCs) driven by nitrite photolysis has been recognized as a significant source of secondary brown carbon (BrC). However, the influence of pH on the conversion kinetics and product distribution of PhCs remains unclear. In this study, three representative PhCs with varying functional groups were selected to examine their aqueous-phase conversion kinetics in the presence of nitrite under different pH conditions and simulated sunlight conditions. The results indicate that as the pH increases, the decay rates of PhCs decrease, following first-order reaction kinetics. These varying decay rates also suggest that different substituents on the benzene ring significantly impact the reactivity of PhCs. The molecular composition of the products is pH-dependent, with 4-nitrocatechol (4NC) emerging as the primary reaction product. A range of conversion products were detected across different pH values: nitrification dominated at low pH, while hydroxylation products increased with rising pH, and polymerization products appeared prominently at high pH. Due to the electron-withdrawing effect of the nitro group on the benzene ring, fewer products formed from 4-nitrophenol were observed, and the visible absorption spectrum also showed a decreasing trend as the reaction progressed across various pH conditions. Toxicity assays on human non-small cell lung cancer cells (A549) revealed that the toxicity of the reaction products decreased with increasing pH. Correspondingly, the accumulation of reactive oxygen species (ROS) and apoptosis rates in cells also declined. This may be due to the fact that at lower pH levels, nitrophenols (NPs), which tend to promote ROS accumulation and cell death, dominate the product mix. This study provides valuable insights into the toxicological properties of secondary organic aerosols (SOA) formed from the photo-oxidation products of PhCs under different pH conditions. These findings contribute to a deeper understanding of the environmental and health impacts of SOA in atmospheric chemistry.

Water-Microdroplet-Driven Interface-Charged Chemistries.

Water has made Earth a habitable planet by electrifying the troposphere. For example, the lightning caused by the electrification and discharge of cloudwater microdroplets is closely related to atmospheric chemistry. Recent work has revealed that a high electric field exists at the interface of water microdroplets, which is ∼3 orders of magnitude higher than the electric field that accounts for lightning. A surge of exotic redox reactions that were recently found over water microdroplets can be contributed by such an interfacial electric field. However, the role of net charge in microdroplet redox chemistry should not be ignored. In this Perspective, we show how redox reactions can be driven by electron transfer pathways in the electrification and discharge process of water microdroplets. Understanding and harnessing the origin and evolution of charged microdroplets are likely to lead to a paradigm shift of electrochemistry, which may play an overlooked role in geological and environmental chemistry.

Effect of silane-doped argon shielding gases for gas metal arc welding of S355

Abstract The welding of steel grades relies primarily on the interaction of the weld metal with doped oxygen components of the shielding gas. This mainly serves to decrease the viscosity and reduce the surface tension of the melt in order to achieve an adjusted material transition. Interference with the ambient atmosphere is undesirable in this context. In order to prevent material-related changes in the microstructure, slag initiators are admixed which promote the precipitation of low-density oxides on the weld seam surface. Manufacturing technology is increasingly striving to eliminate the interaction of atmospheric oxygen in the production process. It is primarily intended to counteract the negative effects of oxygen during manufacturing. For this objective, silane-doped gases for subtractive manufacturing processes and additive manufacturing via the PBF-LB/M process have been considered. Small amounts of silane in conventional inert shielding gases allow partial pressures of oxygen that are comparable to a high vacuum. In the scope of this publication on investigations for welding applications, blind welds on S355 substrate plates were performed using G3Si1 filler material. In addition to the recommended M21, an argon shielding gas with 1.5% silane doping and argon 4.6 are applied for welding. Apart from the observation of the resulting energy input, the weld seams are metallographically characterized. For this purpose, the formation of silicates on the weld seam surface and the development of the weld seam within the base material are investigated. The volume of the weld seam is reduced as a result of the silane doping compared to the M21 application. The composition of the weld metal is significantly influenced by the silane content, leading to an increased manganese content in particular. The silane doping results in an intensified formation of an acicular bainitic structure and an accompanying hardening within the weld metal.

Efficient Nitrate Formation in Fog Events Implicates Fog Interstitial Aerosols as Significant Drivers of Atmospheric Chemistry.

Clouds and fogs, consisting of tiny water droplets formed by the condensation of water in supersaturated air, are vital in atmospheric chemistry, as they facilitate multiphase reactions. While measuring high-altitude cloud is challenging, fog as ground-level clouds offer a unique opportunity for direct observation. In this study, we explored radiation fogs in the North China Plain using an advanced aerosol-fog sampling system to measure the chemical and physical properties of both inactivated interstitial aerosols and activated fog droplet residues. Our findings revealed that efficient nitrate formation primarily occurred on fog interstitial aerosols rather than within fog droplets, with observed fog interstitial aerosol nitrate net production rates reaching up to 3.6 μg m-3 h-1. Box model simulations identified the hydrolysis of NO2 and N2O5 as key pathways for nitrate formation. NO2 hydrolysis was often overlooked in previous studies, contributing 40-79 and 57-76% to total nitrate production during nighttime and daytime fog periods. This oversight suggests that substantial nitrate formation through hydrolysis reactions involving interstitial aerosols may have been neglected. Our results highlight the need for further research into the chemistry of cloud and fog interstitial aerosols and their inclusion in atmospheric chemistry models.

Emission location affects impacts on atmosphere and climate from alternative fuels for Norwegian domestic aviation

Aviation emissions contribute to climate change and local air pollution, with important contributions from non-CO2 emissions. These exhibit diverse impacts on atmospheric chemistry and radiative forcing (RF), varying with location, altitude, and time. Assessments of local mitigation strategies with global emission metrics may overlook this variability, but detailed studies of aviation emissions in areas smaller than continents are scarce. Integrating the AviTeam emission model and OsloCTM3, we quantify CO2, NOx, BC, OC, and SOx emissions, tropospheric concentration changes, RF, region-specific metrics, and assess alternative fuels for Norwegian domestic aviation. Mitigation potentials for a fuel switch to LH2 differ by up to 3.1×108kgCO2-equivalents (GWP20) when using region-specific compared to global metrics. These differences result from a lower, region-specific contribution of non-CO2 emissions, particularly related to NOx. This study underscores the importance of accounting for non-CO2 variability in regional assessments, whether through region-specific metrics or advanced atmospheric modelling techniques.

Synthesis and Characterizations of Dibenzo-Fused Perioctacene.

Dibenzoperioctacene (DBPO) with extended zigzag edges was synthesized and unambiguously characterized by a combination of nuclear magnetic resonance (NMR), mass spectrometry, and single-crystal X-ray diffraction analysis. Variable-temperature (VT) NMR analysis indicated the closed-shell character of DBPO, yet an electron paramagnetic resonance (EPR) signal was observed at room temperature suggesting its potential open-shell diradicaloid nature. The bond lengths in the single-crystal structure of DBPO aligned more closely with those of open-shell teranthene than closed-shell bisanthene. Spin-unrestricted density functional theory (DFT) calculations using various methods supported that ground state of DBPO might be on the borderline between closed- and open-shell singlet states, with a large singlet-triplet energy gap (ΔEST), consistent with the VT-NMR and EPR results. UV-vis-near infrared (NIR) absorption spectrum showed the longest-wavelength peak at 905 nm, marking the NIR optical properties of DBPO. DBPO exhibited a tendency to react with atmospheric oxygen, which additionally hinted at its possible open-shell character. Furthermore, the oxidized species of non-fluorescent DBPO exhibited strong emission at 820 and 915 nm, which opens its potential for oxygen detection via a "turn-on" NIR fluorescence response.

Atmospheric Chemistry of (E)- and (Z)-CF3CF2CH═CHCF2CF3 (HFO-153-10mczz): Kinetics and Mechanisms of the Reactions with Cl Atoms, OH Radicals, and O3.

Smog chamber experiments were conducted to establish the atmospheric chemistry of (E)- and (Z)-CF3CF2CH═CHCF2CF3. Kinetics of the reactions of the two compounds with Cl atoms and OH radicals were measured using relative rate techniques, giving k(Cl + (E)-CF3CF2CH═CHCF2CF3) = (5.63 ± 0.84) × 10-12, k(Cl + (Z)-CF3CF2CH═CHCF2CF3) = (1.17 ± 0.20) × 10-11, k(OH + (E)-CF3CF2CH═CHCF2CF3) = (1.64 ± 0.21) × 10-13, and k(OH + (Z)-CF3CF2CH═CHCF2CF3) = (3.13 ± 0.38) × 10-13 cm3 molecule-1 s-1 in 680 Torr air/N2/O2 diluents at 296 ± 2 K. Rate coefficients for the reactions with O3, k(O3 + (E)-CF3CF2CH═CHCF2CF3) ∼ 1 × 10-22 and k(O3 + (Z)-CF3CF2CH═CHCF2CF3) ≤ 5× 10-24 cm3 molecule-1 s-1, were established using absolute techniques in a 680 Torr air diluent and 296 ± 2 K. The Cl reaction with (E)-CF3CF2CH═CHCF2CF3 gives CF3CF2CHClC(O)CF2CF3 as the sole oxidation product, whereas the reaction with (Z)-CF3CF2CH═CHCF2CF3 also gives rise to the formation of the (E)-isomer in minor yields. The reaction of OH radicals with CF3CF2CH═CHCF2CF3 gives CF3CF2CHO in a yield of 177 ± 17%. The main atmospheric fate of (E)- and (Z)-CF3CF2CH═CHCF2CF3 is the reaction with OH radicals, resulting in overall atmospheric lifetime estimates of 71 and 37 days, for (E)- and (Z)-CF3CF2CH═CHCF2CF3, respectively. The IR absorption cross sections are reported, and the global warming potentials of (E)- and (Z)-CF3CF2CH═CHCF2CF3 for the 20-, 100-, and 500-year time horizons are calculated to be 36, 10, and 3 for the (E)-isomer and 11, 3, and 1 for the (Z)-isomer, respectively. Atmospheric processing of (E)- and (Z)-CF3CF2CH═CHCF2CF3 is expected to yield CF3CF2COOH and CF3COOH in yields of <10%. This study provides a comprehensive description of the atmospheric chemistry and fate of (E)- and (Z)-CF3CF2CH═CHCF2CF3.

Pollution investigation of wintertime VOCs in the coastal atmosphere of the Yellow Sea: Insights from on-line photoionization-induced CI-TOFMS.

Volatile Organic Compounds (VOCs) are pivotal in tropospheric atmospheric chemistry, significantly impacting the formation of photochemical smog, fine particle pollution, and the atmospheric oxidizing potential, all of which affect air quality. Chemical ionization time-of-flight mass spectrometry, renowned for its exceptional sensitivity, precision, and swift response time, has proven to be exceptionally effective for real-time VOCs monitoring. In this study, a custom-built photoionization-induced CI-TOFMS was deployed to individually detect 116 VOCs standard gases specified by the United States Environmental Protection Agency, quantifying their responses and establishing a distinctive mass spectrogram database. A 12-day comparative analysis with online gas chromatography coupled with a flame ionization detector and mass spectrometer demonstrated the high reliability of the PICI-TOFMS, confirming its effectiveness for field VOCs monitoring. During two months of stationary monitoring, the PICI-TOFMS could further refine the timing of pollution events with high temporal resolution and identified four distinct air pollution episodes, including local emissions, coal burning, sand and dust transport and festival-related pollution. Employing a Hysplit model, the Concentration Weighted Trajectory model, and a source apportionment method based on tracer gases, the air trajectories were calculated and contributions from different potential source areas were quantified. Our findings reveal that transport was the main contributor to pollution in December 2022, while burning was the primary source in January 2023. This study refines our understanding of the dynamics of air pollution, providing valuable insights into the temporal and spatial distribution of VOCs and their sources.

Probing coherence properties of shallow implanted NV snsembles under different oxygen terminations

Abstract Nitrogen vacancy (NV) color centers in diamond have shown great potential for various applications in quantum technology due to their long coherence times, high sensitivity to magnetic fields and atomic scale resolution. However, one major challenge in utilizing near surface NV centers is the decoherence caused by spins and charges fluctuating on the surface, which affects the spin properties of the sensors. To reduce the induced noise, various oxygen surface treatments such as low power oxygen plasma treatment and annealing under oxygen atmosphere have been explored to terminate the diamond surface and reduce its impact on NV coherence. We showed that the NV center's coherence time can be enhanced up to a factor of 3 over a large spectral range of noise. Double electron electron resonance (DEER) measurements revealed an extra source of decoherence, scaling similarly as the P1 spin bath. The improvement in coherence times is accompanied with an increase in measured ketone/ether content and reduction of sp2 signal in X-ray photoelectron spectroscopy (XPS) measurements. Finally we compared the performance of different NV ensembles and surface treatments for sensing external proton spins. The oxygen annealing is an effective procedure of enhancing the spin coherence times and reducing broad band spin noise experienced by shallow implanted ensemble NV centers in diamond.

Single Step Synthesis of Non-symmetric Azoarenes Using Buchwald-Hartwig Amination.

Aromatic azo compounds stand as a highly sought-after class of substances owing to their extensive array of applications across various fields. Despite their significance, their synthesis often presents challenges, requiring either multistep reactions or being restricted to specific substrate types. In this study, we are showing the universality and mechanistic aspects of a one-step approach for synthesis of nonsymmetrical azoarenes via the Buchwald-Hartwig amination reaction of (pseudo)haloaromatics with arylhydrazines, conducted in the presence of atmospheric oxygen. This reaction protocol yields products in up to 85% yield and is compatible with a wide class of substituents, making it highly adaptable. Notably, the inclusion of BINAP as a ligand plays a pivotal role in achieving favorable outcomes. This study not only offers a versatile solution to a long-standing synthetic challenge but also provides experimental and computational insights into the mechanisms driving the reaction.

Study on Surface Quality Analysis of an Uncoated Boron Steel and Its Oxide Layer Suppression Method for Hot Stamping.

This study investigates the effects of hot stamping on boron steel surface properties, comparing uncoated steel to Al-Si-coated steel, with a focus on developing atmosphere-controlled hot stamping technology. Experiments using a hat-shaped specimen revealed that uncoated steel formed a thick oxide layer due to exposure to atmospheric oxygen at high temperatures, negatively impacting surface quality and weldability. In contrast, the Al-Si-coated steel showed no oxide formation. Although uncoated steel exhibited higher average Vickers hardness, the detrimental effects of the oxide layer on weld quality necessitate advancements in process technology. A lab-scale hot stamping simulator was developed to control atmospheric oxygen levels, utilizing a donut-shaped induction heating coil to heat the material above 1000 °C, followed by rapid cooling in a forming die. Results demonstrated that maintaining oxygen concentrations below 6% significantly reduced oxide layer thickness, with near-vacuum conditions eliminating oxide formation altogether. These findings emphasize the critical role of oxygen control in enhancing the surface quality and weldability of uncoated boron steel for ultra-high-strength automotive applications, potentially reducing manufacturing costs while ensuring part performance.