Article
Energy & Fuels
Yaozong Duan, Anhao Zhong, Zhen Huang, Dong Han
Summary: This study calculated the rate constants of the reaction between cyclopentanol and hydroxyl radical using multistructural canonical variational transition state theory. The results highlighted the importance of variational and multistructural torsional anharmonicity effects, with quantum tunneling effect being negligible. While the total rate constants were in good agreement with literature estimates, significant discrepancies were observed in the branching ratios of reaction channels.
Article
Chemistry, Organic
Julia A. Turner, Timur Adrianov, Mark S. Taylor
Summary: The use of quinuclidine and a light-absorbing photoredox catalyst allows for site-selective radical formation from carbohydrate substrates. However, the factors influencing the site selectivity in hydrogen atom transfer (HAT) step have not been fully understood. This study used computational modeling to investigate the relative rates of HAT to the quinuclidinium radical cation from pyranosides and furanosides with different configurations and substitution patterns, revealing the important role of C-H...O hydrogen bonds in stabilizing transition states.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Thermodynamics
Yaozong Duan, Zhen Huang, Dong Han
Summary: This study investigates the temperature-dependent rate constants and branching ratios of hydrogen atom abstraction reactions from n-propanol and iso-propanol by HO2 radical. The multistructural torsional anharmonicity effects significantly influence the calculation of rate constants, highlighting the importance of accurate calculation efforts for predicting reaction pathways and kinetic behavior. Incorporating the newly calculated rate constants into a chemical kinetic model results in decreased fuel reactivity and better prediction of key oxidation intermediates in propanol oxidation.
COMBUSTION AND FLAME
(2021)
Article
Chemistry, Physical
John M. Roscoe
Summary: This study presents the kinetic measurements of the reactions between atomic bromine and the three isomers of trimethylbenzene at various temperatures. The experimental results show the temperature dependence of the rate coefficients for these reactions. Additionally, the enthalpies and entropies of activation for the reactions of trimethylbenzenes with bromine are compared to those of toluene and xylenes with bromine.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Energy & Fuels
Zhe Ren, Yaozong Duan, Wenming Yang, Dong Han
Summary: The rate constants for the H-abstraction reactions of C5H12 + NO2 were calculated using high-accuracy electronic structure calculations and transition state theory. The results indicate that implementing these reaction rate constants can improve the predictive performance of kinetic models and enhance the understanding of the mutual reactions between large hydrocarbon fuels and NOx.
Article
Thermodynamics
Yuxiang Zhu, Chong-Wen Zhou, Alexander A. Konnov
Summary: In this study, the reaction kinetics of hydrogen-abstraction reactions from methoxymethanol by various radicals were investigated using high-level ab initio calculations. It was found that the H-abstraction reactions from the secondary carbon atom of methoxymethanol are favored pathways. Different radicals have different rate constants for hydrogen-abstraction reactions at different temperatures.
COMBUSTION AND FLAME
(2021)
Article
Chemistry, Multidisciplinary
Zhikai Zhang, Qing Wang, Haiming Liu, Tao Li, Yi Ren
Summary: This study presents a new strategy for constructing porous organophosphorus polymers (POPPs) with high surface areas and ultramicroporous structures. By utilizing an efficient transition-metal-catalyzed phosphorus-carbon coupling reaction, the self-accelerating characteristic of POPPs is achieved, leading to high surface areas and uniform ultramicroporosity. Kinetic and solid-state NMR studies reveal the impact of the coupling reaction on the crosslinking environments and porous structures of POPPs. Furthermore, the study demonstrates the dependence of CO2 uptake capacity of POPPs on their porous structures.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Chemistry, Multidisciplinary
Michela Salamone, Marco Galeotti, Eduardo Romero-Montalvo, Jeffrey A. van Santen, Benjamin D. Groff, James M. Mayer, Gino A. DiLabio, Massimo Bietti
Summary: The study investigated the applicability of the Evans-Polanyi relationship in HAT reactions, measured rate constants for HAT from C-H bonds to the cumyloxyl radical, and calculated consistent gas-phase C-H bond dissociation enthalpies. The analysis revealed distinct behaviors for different groups of substrates, indicating a qualitative connection between Bernasconi's principle of nonperfect synchronization and Marcus theory.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2021)
Article
Chemistry, Physical
Zong-Ying Liu, Yu-Chen Wei, Pi-Tai Chou
Summary: This study investigated the thermodynamics and kinetics correlation of excited-state intramolecular proton transfer (ESIPT) using TD-DFT calculations, revealing a linear relationship between Delta G(T*-N*) and Delta G(double dagger) as well as the applicability of Bell-Evans-Polanyi (BEP) principle in the ESIPT family.
JOURNAL OF PHYSICAL CHEMISTRY A
(2021)
Article
Chemistry, Physical
Jonas Elfert, Anup Bhunia, Constantin G. Daniliuc, Armido Studer
Summary: In this study, a radical transformation that enables intramolecular oxygen atom transfer to alkenes using the nitro functionality in nitroarenes as an oxygen donor is disclosed. The reaction proceeds via iron-catalyzed metal hydrogen atom transfer to alkenes and subsequent oxygenation, resulting in alkene hydration. Compared to intermolecular radical oxygenation, the intramolecular variant offers advantages, particularly in terms of diastereoselective radical hydration of conformationally flexible alkenes. The aryl moiety connecting the reactive NO2-functionality to the alkene substrate can be cleaved after oxygen transfer, yielding products derived from a formal diastereoselective intermolecular alkene hydration. Additionally, the resulting aniline entity after oxygen transfer can be used for the construction of nitrogen-containing heterocycles.
Article
Thermodynamics
Jinhui Yu, Shanshan Ruan, Hongwei Song, Lidong Zhang, Minghui Yang
Summary: The study predicts the rate constants of reactions between alkyl ester and H atom using machine learning methods, and the results show that the XGB-FNN model has better performance in predicting the rate constants in the temperature range of combustion. This machine learning method is important for accurate prediction of rate constants in larger systems.
COMBUSTION AND FLAME
(2023)
Article
Energy & Fuels
Liuchao Lian, Yunrui He, Lili Xing, Cheng Xie, Zhandong Wang, Xuetao Wang, Haojie Li
Summary: Hydrogen abstraction reactions of alkylated cycloalkane by radicals have a fundamental role in combustion and atmospheric chemistry. In this study, the kinetics of hydrogen abstraction reactions between npropylcyclohexane (nPCH) and n-butylcyclohexane (nBCH) molecules and hydrogen atom were investigated. The rate constants were calculated for a wide temperature range using canonical transition state theory coupled with multistructural torsional anharmonicity effect. The results show that the multistructural torsional anharmonicity influences competitive relationships and the reactivity of cycloalkanes, which challenges the commonly used pyrolysis model.
Article
Chemistry, Physical
Ning Dai, Zhipeng Cai, Xu Zhang, Kejian Li
Summary: The effects of magnetic fields ranging from 0 T to 0.13 T on the photochemical reactions between benzophenone and isopropanol were studied. The results showed that increasing the applied magnetic field strength led to an increased production rate of the product and a shortened induction period. A new theoretical model was used to explain the magnetic phenomenon in the initiation process of the radical reaction.
Article
Thermodynamics
Caiyu Yang, Jin-Tao Chen, Xincheng Zhu, Xin Bai, Yang Li, Kiran K. Yalamanchi, S. Mani Sarathy, S. Scott Goldsborough, Song Cheng, Henry J. Curran, Chong-Wen Zhou
Summary: This study systematically investigates the hydrogen atom abstraction by methyl peroxy (CH3OO) radicals in the gasoline/ethanol interacting chemistry. The high-pressure limiting rate constants for various components were calculated, and it was found that the abstraction of allylic hydrogen atoms from 1-hexene is the fastest at low temperatures.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Correction
Chemistry, Physical
Wenqi Chen, Xuan Guo, Lifang Chen, Ruiming Zhang, Yan Li, Haisong Feng, Xuefei Xu, Xin Zhang
Summary: The article provides a corrected version of a kinetics study on hydrogen abstraction reactions of cyclopentane by hydrogen, methyl, and ethyl radicals, conducted by Wenqi Chen et al. This study was published in Phys. Chem. Chem. Phys. in 2021.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2021)
Article
Chemistry, Organic
Massimo Bietti, Erica Cucinotta, Gino A. DiLabio, Osvaldo Lanzalunga, Andrea Lapi, Marco Mazzonna, Eduardo Romero-Montalvo, Michela Salamone
JOURNAL OF ORGANIC CHEMISTRY
(2019)
Article
Chemistry, Multidisciplinary
Marco Cianfanelli, Giorgio Olivo, Michela Milan, Robertus J. M. Klein Gebbink, Xavi Ribas, Massimo Bietti, Miquel Costas
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2020)
Article
Chemistry, Physical
Margarida Borrell, Sergio Gil-Caballero, Massimo Bietti, Miquel Costas
Article
Chemistry, Multidisciplinary
Laia Vicens, Massimo Bietti, Miquel Costas
Summary: The use of bioinspired manganese catalysts and H2O2 under mild conditions allows for the efficient preparation of modified alpha-amino acids. This method demonstrates outstanding site-selectivity and diastereoselectivity, potentially serving as an alternative to established organometallic procedures.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Organic
Teo Martin, Marco Galeotti, Michela Salamone, Fengjiao Liu, Yanmin Yu, Meng Duan, K. N. Houk, Massimo Bietti
Summary: A study on the reactions of the cumyloxyl radical with monosubstituted cyclopentanes and cyclohexanes showed that cyclopentanes predominantly functionalize at C-1, while the importance of HAT from C-1 decreases with increasing steric bulk in cyclohexanes. Determinants of site-selectivity include the nature of the HAT reagent, C-H bond strengths, and torsional effects.
JOURNAL OF ORGANIC CHEMISTRY
(2021)
Article
Chemistry, Multidisciplinary
Michela Salamone, Marco Galeotti, Eduardo Romero-Montalvo, Jeffrey A. van Santen, Benjamin D. Groff, James M. Mayer, Gino A. DiLabio, Massimo Bietti
Summary: The study investigated the applicability of the Evans-Polanyi relationship in HAT reactions, measured rate constants for HAT from C-H bonds to the cumyloxyl radical, and calculated consistent gas-phase C-H bond dissociation enthalpies. The analysis revealed distinct behaviors for different groups of substrates, indicating a qualitative connection between Bernasconi's principle of nonperfect synchronization and Marcus theory.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2021)
Article
Chemistry, Organic
Marco Galeotti, Chiara Trasatti, Sergio Sisti, Michela Salamone, Massimo Bietti
Summary: A kinetic study was conducted to investigate the hydrogen atom transfer (HAT) reactions from nitrogen-containing heterocycles to the cumyloxyl radical. The study revealed that HAT occurs through hyperconjugative overlap between the C-H bonds and the N-C???O π system. The size of the ring and the functional group have significant effects on the reaction rate.
JOURNAL OF ORGANIC CHEMISTRY
(2022)
Article
Chemistry, Multidisciplinary
Fengjiao Liu, Siqi Ma, Zeying Lu, Anjanay Nangia, Meng Duan, Yanmin Yu, Guochao Xu, Ye Mei, Massimo Bietti, K. N. Houk
Summary: Density functional theory calculations were employed to study the reactions of radicals with C-H bonds in different environments, and modified Evans-Polanyi treatments were used to analyze the variations in activation barriers, with a focus on polarity and unsaturation effects. The study revealed the quantitative importance of the thermodynamics of reactions and polar effects in determining barriers to reactions involving radicals and C-H bonds.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Chemistry, Multidisciplinary
Marco Galeotti, Laia Vicens, Michela Salamone, Miquel Costas, Massimo Bietti
Summary: The C(sp(3))-H bond oxygenation of cyclopropane-containing mechanistic probes has been studied using hydrogen peroxide catalyzed by manganese complexes. The study showed the presence of both unrearranged and rearranged oxygenation products, suggesting the involvement of cationic intermediates and different pathways. The selective formation of either unrearranged or rearranged product in high yield can be achieved by choosing appropriate catalyst structure and reaction conditions.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Chemistry, Organic
Sergio Sisti, Fabio Ioele, Filippo Scarchilli, Marco Galeotti, Gino A. Dilabio, Michela Salamone, Massimo Bietti
Summary: Kinetic and product studies were conducted on the reactions of tert-alkoxyl radicals with secondary and tertiary alkanamides bearing benzylic alpha-C H bonds. The results revealed the exclusive HAT from the benzylic alpha-C H bonds, indicating a lack of benzylic activation and the presence of steric and stereoelectronic effects. In the isoindoline and tetrahydroisoquinoline derivatives, significant increases in kH were observed due to optimal overlap with both the phenyl p-system and the amide p-system or amine nitrogen lone pair, demonstrating the strong contribution of stereoelectronic activation.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Marco Galeotti, Woojin Lee, Sergio Sisti, Martina Casciotti, Michela Salamone, K. N. Houk, Massimo Bietti
Summary: A product and DFT computational study was conducted on the reactions of 3-ethyl-3-(trifluoromethyl)dioxirane (ETFDO) with bicyclic and spirocyclic hydrocarbons bearing cyclopropyl groups. The reactions exhibited good site-selectivities and diastereoselectivities, which were supported by calculated activation free energies. The computational results showed that hyperconjugative interactions between the cyclopropane C-C bonding orbitals and the sigma* orbitals of the C-H bonds activated these bonds towards hydrogen atom transfer to ETFDO.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Multidisciplinary
Sergio Sisti, Marco Galeotti, Filippo Scarchilli, Michela Salamone, Miquel Costas, Massimo Bietti
Summary: A detailed study on C(sp(3))-H bond oxygenation reactions catalyzed by [Mn(OTf)(2)((TIPS)mcp)] complex was conducted, showing that the introduction of electron-withdrawing functional groups in different solvents significantly increased site-selectivity and product yield. The study also achieved selective control over multiple methylenic sites.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Multidisciplinary
Andrea Palone, Guillem Casadevall, Sergi Ruiz-Barragan, Arnau Call, Siilvia Osuna, Massimo Bietti, Miquel Costas
Summary: This study describes a catalytic enantioselective hydroxylation method of tertiary C-H bonds in cyclohexane scaffolds using an evolved manganese catalyst and H2O2. The catalytic system provides structural complementarity to the substrate similarly to lock-and-key recognition in enzymatic active sites. Theoretical calculations reveal that enantioselectivity is determined by the precise fitting of the substrate scaffold into the catalytic site through a network of complementary weak non-covalent interactions. Stereoretentive C(sp(3))-H hydroxylation results in the generation of multiple stereogenic centers in a single step, which can be orthogonally manipulated to obtain a variety of chiral scaffolds from a single precursor molecule.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Review
Chemistry, Multidisciplinary
Marco Galeotti, Michela Salamone, Massimo Bietti
Summary: Direct functionalization of C(sp(3))-H bonds is a key focus in developing new synthetic methods. Among intermolecular C-H bond functionalization strategies, hydrogen atom transfer (HAT) methods using radical or radical-like reagents have gained increasing attention due to their ability to introduce a variety of atoms and groups in mild conditions. Selectivity control over aliphatic C-H bonds is crucial and factors influencing it have been discussed. This review article provides a detailed description of HAT reagents, associated mechanistic features, and selectivity patterns observed in the functionalization of increasingly complex substrates, based on an analysis of recent literature.
CHEMICAL SOCIETY REVIEWS
(2022)
Article
Chemistry, Multidisciplinary
Teo Martin, Michela Salamone, Massimo Bietti
CHEMICAL COMMUNICATIONS
(2019)