Barrierless tautomerization of Criegee intermediates via acid catalysis

2014 ◽  
Vol 16 (42) ◽  
pp. 22968-22973 ◽  
Author(s):  
Manoj Kumar ◽  
Daryle H. Busch ◽  
Bala Subramaniam ◽  
Ward H. Thompson
Keyword(s):  
Electronic Structure ◽  
Hydrogen Atom ◽  
Organic Acids ◽  
Acid Catalysis ◽  
Electronic Structure Calculations ◽  
Hydrogen Atom Transfer ◽  
Atom Transfer ◽  
Criegee Intermediates ◽  
Structure Calculations

Electronic structure calculations indicate that the organic acids catalyze the tautomerization of Criegee intermediates via a 1,4 β-hydrogen atom transfer to yield a vinyl hydroperoxide to such an extent that it becomes a barrierless process.

Reaction mechanism and kinetics of the atmospheric oxidation of 1,4-thioxane by NO3 — A theoretical study

2012 ◽  
Vol 90 (4) ◽  
pp. 384-394 ◽  
Author(s):  
L. Sandhiya ◽  
P. Kolandaivel ◽  
K. Senthilkumar
Keyword(s):  
Electronic Structure ◽  
Hydrogen Atom ◽  
Density Functional ◽  
Electronic Structure Calculations ◽  
State Theory ◽  
Hydrogen Atom Transfer ◽  
Basis Set ◽  
Radical Intermediate ◽  
Atmospheric Species ◽  
Structure Calculations

Volatile organic compounds (VOCs) are emitted as pollutants into the atmosphere from many natural and artificial sources. The oxidation of VOCs by atmospheric species plays a key role in the degradation of VOCs. In the present investigation, the atmospheric degradation of a cyclic organosulfur compound, 1,4-thioxane, by an NO3• radical is studied. Pathways for the reaction of 1,4-thioxane with the NO3• radical were modeled through electronic structure calculations using density functional theory methods B3LYP, M06-2X, and MP2 with the 6–31G(d,p) basis set. The NO3•-initiated reaction of 1,4-thioxane was found to proceed in three ways: by single-hydrogen atom abstraction, by direct transfer of the O atom of NO3• to the S atom moiety of 1,4-thioxane, or by two-hydrogen atom transfer reactions leading to the formation of a peroxy radical intermediate, which further undergoes secondary reactions with other atmospheric species. Structures, energies, and vibrational frequencies obtained from M06-2X/6–31G(d,p) electronic structure calculations were subsequently used to perform canonical variational transition-state theory calculations to determine the rate constants over the temperature range of 278–350 K and to study the lifetime of 1,4-thioxane in the atmosphere. The rate constant calculated for the reaction of 1,4-thioxane with the NO3• radical is in good agreement with the available experimental data.

On the Mechanisms of Hydrogen-Atom Transfer from Water to the Heteronuclear Oxide Cluster [Ga2Mg2O5].+: Remarkable Electronic Structure Effects

2015 ◽  
Vol 54 (40) ◽  
pp. 11861-11864 ◽  
Author(s):  
Jilai Li ◽  
Shaodong Zhou ◽  
Xiao-Nan Wu ◽  
Shiya Tang ◽  
Maria Schlangen ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Hydrogen Atom ◽  
Hydrogen Atom Transfer ◽  
Atom Transfer ◽  
Oxide Cluster

Direct Cyclization of Alkenyl Thioester via Transition Metal‐hydrogen Atom Transfer/radical‐polar Crossover Mechanism

2019 ◽  
Author(s):  
Shiori Date ◽  
Kensei Hamasaki ◽  
Karen Sunagawa ◽  
Hiroki Koyama ◽  
Chikayoshi Sebe ◽  
...  
Keyword(s):  
Natural Products ◽  
Hydrogen Atom ◽  
Transition Metal ◽  
Hydrogen Atom Transfer ◽  
Synthetic Method ◽  
Atom Transfer ◽  
Reaction Conditions ◽  
Hydride Hydrogen ◽  
Sulfur Heterocycles ◽  
One Step

<div>We report here a catalytic, Markovnikov selective, and scalable synthetic method for the synthesis of saturated sulfur heterocycles, which are found in the structures of pharmaceuticals and natural products, in one step from an alkenyl thioester. Unlike a potentially labile alkenyl thiol, an alkenyl thioester is stable and easy to prepare. The powerful Co catalysis via a cobalt hydride hydrogen atom transfer and radical-polar crossover mechanism enabled simultaneous cyclization and deprotection. The substrate scope was expanded by the extensive optimization of the reaction conditions and tuning of the thioester unit.</div>

Message Passing Neural Networks for Partial Charge Assignment to Metal-Organic Frameworks

2020 ◽  
Author(s):  
Ali Raza ◽  
Arni Sturluson ◽  
Cory Simon ◽  
Xiaoli Fern
Keyword(s):  
Electronic Structure ◽  
Message Passing ◽  
Gas Adsorption ◽  
Metal Organic Frameworks ◽  
Computational Cost ◽  
Electronic Structure Calculations ◽  
High Fidelity ◽  
Partial Charges ◽  
Metal Organic ◽  
Structure Calculations

Virtual screenings can accelerate and reduce the cost of discovering metal-organic frameworks (MOFs) for their applications in gas storage, separation, and sensing. In molecular simulations of gas adsorption/diffusion in MOFs, the adsorbate-MOF electrostatic interaction is typically modeled by placing partial point charges on the atoms of the MOF. For the virtual screening of large libraries of MOFs, it is critical to develop computationally inexpensive methods to assign atomic partial charges to MOFs that accurately reproduce the electrostatic potential in their pores. Herein, we design and train a message passing neural network (MPNN) to predict the atomic partial charges on MOFs under a charge neutral constraint. A set of ca. 2,250 MOFs labeled with high-fidelity partial charges, derived from periodic electronic structure calculations, serves as training examples. In an end-to-end manner, from charge-labeled crystal graphs representing MOFs, our MPNN machine-learns features of the local bonding environments of the atoms and learns to predict partial atomic charges from these features. Our trained MPNN assigns high-fidelity partial point charges to MOFs with orders of magnitude lower computational cost than electronic structure calculations. To enhance the accuracy of virtual screenings of large libraries of MOFs for their adsorption-based applications, we make our trained MPNN model and MPNN-charge-assigned computation-ready, experimental MOF structures publicly available.<br>

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