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Radical-radical reactions can generate two channels with high and low spins. In this work, ten radical-radical reactions with different spin channels and four radical-molecule reactions in hydrogen-oxygen combustion were systematically investigated from a theoretical perspective. The potential energy surface (PES) of radical-radical reactions reveals that the high- and low-spin states of the reactant are energetically degenerate and the two channels are energetically feasible. The difference in rate constants between the high- and low-spin channels gradually decreases as the temperature increases. Then, the kinetic parameters of the 14 bimolecular reactions in the hydrogen-oxygen mechanism of the University of California, San Diego (UCSD), were replaced to simulate the ignition delay time and laminar flame speed. The simulation results agree well with the available experimental findings, indicating the necessity of considering both high- and low-spin channels for kinetic simulation.
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http://dx.doi.org/10.1021/acs.jpca.4c02689 | DOI Listing |
J Am Chem Soc
September 2025
Department of Chemistry and Biochemistry, The University of Texas at Dallas, Richardson, Texas 75080-3021, United States.
The direct transformation of C-H bonds into C-C bonds via cross-dehydrogenative coupling (CDC) represents a powerful strategy in synthetic chemistry, enabling streamlined bond construction without the need for prefunctionalized substrates. While traditional CDC approaches rely on polar mechanisms and preactivation of one of the C-H partners, recent advances have introduced radical-based strategies that employ a hydrogen atom transfer (HAT) approach to access carbon-centered radicals from unactivated substrates. Herein, we report a nickel-catalyzed CDC reaction between aldehydes and alkenes for the synthesis of skipped enones, leveraging aryl radicals as intermolecular HAT agents.
View Article and Find Full Text PDFJ Am Chem Soc
September 2025
Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, P. R. China.
The direct cross-coupling of unactivated alkyl halides with aryl or heteroaryl partners remains a fundamental challenge in synthetic chemistry due to their inertness and propensity for side reactions. Herein, we report a transition-metal-free electrochemical halogen-atom transfer strategy that enables efficient alkyl radical cross-coupling via convergent paired electrolysis. In this system, anodically generated α-aminoalkyl radicals mediate the activation of alkyl iodides, while aryl/heteroaryl aldehydes or nitriles undergo cathodic reduction to afford persistent ketyl radical anions or aryl radical anions.
View Article and Find Full Text PDFOrg Lett
September 2025
College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, P. R. China.
2-Alkylindoles are privileged motifs that serve as versatile intermediates and building blocks in synthetic and medicinal chemistry. Herein, we report a photoinduced, EDA-complex-enabled C2-benzylic C(sp)-H alkylation of indoles with bromides through radical cross-coupling. This developed protocol provides facile access to 2-alkylindoles from structurally varied 2-methylindoles and bromides under mild reaction conditions with simple operation.
View Article and Find Full Text PDFJ Chem Phys
September 2025
MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science, Guangdong Provincial Key Laboratory of Laser Life Science, Guangzhou Key Laboratory of Spectral Analysis and Functional Probes, College of Biophotonics, School of Optoelectronic Science and Engineering, South China Normal Un
Propargyl radical (•C3H3) and butadienyl radical (•i-C4H5) are two crucial intermediates in combustion and astrochemistry, particularly in the formation of C7H8 aromatics such as toluene. However, the precise formation mechanisms of the first-ring aromatics through C3 + C4 reactions have remained ambiguous. This study explores the detailed potential energy surface (PES) of C7H8 at the •C3H3 + •i-C4H5 entrance reaction channel, alongside conducting kinetic calculations and modeling.
View Article and Find Full Text PDFInt J Radiat Biol
September 2025
Graduate School of Science, Rikkyo (St. Paul's) University, Tokyo, Japan.
Purpose: This study investigated the impact of ultra-high dose rate (UHDR) proton radiotherapy on DNA damage compared to conventional dose rate (CONV) radiotherapy. We hypothesized that the unique physicochemical processes associated with UHDR could lead to a reduction of DNA damage. Thus, the aim of this study is to clarify the time scale of the physicochemical processes in which the suppression of SSBs by UHDR proton irradiation occurs.
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