Experimental Investigations and Quantum−Chemical Calculations of Isocyanate-Based Chemically Modified Bitumen And its Crosslinking Behaviours

2021 ◽  
Author(s):  
Tianshuai Li ◽  
Zixiang Guo ◽  
Guoyang Lu ◽  
Liang Dong ◽  
Bin Hong ◽  
...  
Keyword(s):  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Experimental Investigations ◽  
Modified Bitumen ◽  
Chemically Modified

Quantum Chemical Calculations and Experimental Investigations of Molecular Actinide Oxides

2015 ◽  
Vol 115 (4) ◽  
pp. 1725-1759 ◽  
Author(s):  
Attila Kovács ◽  
Rudy J. M. Konings ◽  
John K. Gibson ◽  
Ivan Infante ◽  
Laura Gagliardi
Keyword(s):  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Experimental Investigations ◽  
Actinide Oxides

Discovery of a Difluoroglycine Synthesis Method through Quantum Chemical Calculations

2020 ◽  
Author(s):  
Tsuyoshi Mita ◽  
Yu Harabuchi ◽  
Satoshi Maeda
Keyword(s):  
Quantum Chemical Calculations ◽  
Experimental Verification ◽  
Quantum Chemical ◽  
Synthesis Method ◽  
Target Product ◽  
Systematic Exploration ◽  
Hands On ◽  
Retrosynthetic Analysis ◽  
Synthetic Routes ◽  
Verification Process

The systematic exploration of synthetic pathways to afford a desired product through quantum chemical calculations remains a considerable challenge. In 2013, Maeda et al. introduced ‘quantum chemistry aided retrosynthetic analysis’ (QCaRA), which uses quantum chemical calculations to search systematically for decomposition paths of the target product and propose a synthesis method. However, until now, no new reactions suggested by QCaRA have been reported to lead to experimental discoveries. Using a difluoroglycine derivative as a target, this study investigated the ability of QCaRA to suggest various synthetic paths to the target without relying on previous data or the knowledge and experience of chemists. Furthermore, experimental verification of the seemingly most promising path led to the discovery of a synthesis method for the difluoroglycine derivative. The extent of the hands-on expertise of chemists required during the verification process was also evaluated. These insights are expected to advance the applicability of QCaRA to the discovery of viable experimental synthetic routes.

Discovery of a Difluoroglycine Synthesis Method through Quantum Chemical Calculations

2020 ◽  
Author(s):  
Tsuyoshi Mita ◽  
Yu Harabuchi ◽  
Satoshi Maeda
Keyword(s):  
Quantum Chemical Calculations ◽  
Experimental Verification ◽  
Quantum Chemical ◽  
Synthesis Method ◽  
Target Product ◽  
Systematic Exploration ◽  
Hands On ◽  
Retrosynthetic Analysis ◽  
Synthetic Routes ◽  
Verification Process

The systematic exploration of synthetic pathways to afford a desired product through quantum chemical calculations remains a considerable challenge. In 2013, Maeda et al. introduced ‘quantum chemistry aided retrosynthetic analysis’ (QCaRA), which uses quantum chemical calculations to search systematically for decomposition paths of the target product and propose a synthesis method. However, until now, no new reactions suggested by QCaRA have been reported to lead to experimental discoveries. Using a difluoroglycine derivative as a target, this study investigated the ability of QCaRA to suggest various synthetic paths to the target without relying on previous data or the knowledge and experience of chemists. Furthermore, experimental verification of the seemingly most promising path led to the discovery of a synthesis method for the difluoroglycine derivative. The extent of the hands-on expertise of chemists required during the verification process was also evaluated. These insights are expected to advance the applicability of QCaRA to the discovery of viable experimental synthetic routes.

The Nature of Chemisorbed CO2 in Zeolite A

2019 ◽  
Author(s):  
Przemyslaw Rzepka ◽  
Zoltán Bacsik ◽  
Andrew J. Pell ◽  
Niklas Hedin ◽  
Aleksander Jaworski
Keyword(s):  
Solid State ◽  
Ir Spectroscopy ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Surface Coverage ◽  
Gas Mixtures ◽  
Mas Nmr ◽  
Significant Fraction ◽  
Zeolite A

Formation of CO<sub>3</sub><sup>2-</sup> and HCO<sub>3</sub><sup>-</sup> species without participation of the framework oxygen atoms upon chemisorption of CO<sub>2</sub> in zeolite |Na<sub>12</sub>|-A is revealed. The transfer of O and H atoms is very likely to have proceeded via the involvement of residual H<sub>2</sub>O or acid groups. A combined study by solid-state <sup>13</sup>C MAS NMR, quantum chemical calculations, and <i>in situ</i> IR spectroscopy showed that the chemisorption mainly occurred by the formation of HCO<sub>3</sub><sup>-</sup>. However, at a low surface coverage of physisorbed and acidic CO<sub>2</sub>, a significant fraction of the HCO<sub>3</sub><sup>-</sup> was deprotonated and transformed into CO<sub>3</sub><sup>2-</sup>. We expect that similar chemisorption of CO<sub>2</sub> would occur for low-silica zeolites and other basic silicates of interest for the capture of CO<sub>2</sub> from gas mixtures.

Mechanistic Investigation of Rh(I)-Catalyzed Asymmetric Suzuki-Miyaura Coupling with Racemic Allyl Halides

2019 ◽  
Author(s):  
Lucy van Dijk ◽  
Ruchuta Ardkhean ◽  
Mireia Sidera ◽  
Sedef Karabiyikoglu ◽  
Özlem Sari ◽  
...  
Keyword(s):  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Experimental Studies ◽  
Mechanistic Investigation ◽  
Allyl Halides

A mechanism for Rh(I)-catalyzed asymmetric Suzuki-Miyaura coupling with racemic allyl halides is proposed based on a combination of experimental studies and quantum chemical calculations. <br>

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