scholarly journals Ag2O versus Cu2O in the Catalytic Isomerization of Coordinated Diaminocarbenes to Formamidines: A Theoretical Study

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 491
Author(s):  
Juan F. Van der Maelen ◽  
Javier Ruiz
Keyword(s):  
Reaction Mechanism ◽  
Nitrogen Atom ◽  
Carbon Atom ◽  
Transition State ◽  
Theoretical Study ◽  
Theoretical Calculations ◽  
Experimental Results ◽  
Similar Reaction ◽  
Isomerization Process ◽  
Catalytic Isomerization

DFT theoretical calculations for the Ag2O-induced isomerization process of diaminocarbenes to formamidines, coordinated to Mn(I), have been carried out. The reaction mechanism found involves metalation of an N-H residue of the carbene ligand by the catalyst Ag2O and the formation of a key transition state showing a μ-η2:η2 coordination of the formamidinyl ligand between manganese and silver, which allows a translocation process of Mn(I) and silver(I) ions between the carbene carbon atom and the nitrogen atom, before the formation of the formamidine ligand is completed. Calculations carried out using Cu2O as a catalyst instead of Ag2O show a similar reaction mechanism that is thermodynamically possible, but highly unfavorable kinetically and very unlikely to be observed, which fully agrees with experimental results.

SEMICONDUCTOR BEHAVIOR OF 2, 5-AROMATIC DISUBSTITUTED PYROLLES, AN EXPERIMENTAL AND THEORETICAL STUDY

2012 ◽  
Vol 1483 ◽  
Author(s):  
L. Fomina ◽  
C. Y. León Valdivieso ◽  
G. Zaragoza Galán ◽  
M. Bizarro ◽  
I. P. Zaragoza ◽  
...  
Keyword(s):  
Thin Films ◽  
Nitrogen Atom ◽  
Theoretical Study ◽  
Theoretical Calculations ◽  
Electrical Characterization ◽  
Semiconductor Behavior ◽  
Substituted Pyrroles ◽  
Nitro Benzene

ABSTRACTTheoretical calculations were performed on 2, 5-aromatic substituted pyrroles which have a nitro-benzene or a cyano-benzene link to the nitrogen atom of the pyrrol fragment. The molecules manifested interesting semiconductor behavior that was confirmed when thin films were prepared and their corresponding electrical characterization undertaken. The reason for this behavior is discussed, with reference to the electron withdrawing feature of the substituents in the benzene chain.

Asymmetric cyclopropanation of chiral (1-phosphoryl)vinyl sulfoxides: A new approach to constrained analogs of biologically active compounds

2005 ◽  
Vol 77 (12) ◽  
pp. 2091-2098 ◽  
Author(s):  
Marian Mikołajczyk
Keyword(s):  
Transition State ◽  
Total Synthesis ◽  
Bioactive Compounds ◽  
Theoretical Calculations ◽  
Experimental Results ◽  
Biologically Active ◽  
Active Compounds ◽  
New Approach ◽  
Cyclic Analog ◽  
Asymmetric Cyclopropanation

This account outlines the results obtained in the author's laboratory on the asymmetric cyclopropanation of enantiopure 1-phosphorylvinyl p-tolyl sulfoxides with sulfur ylides and diazoalkanes. Based on experimental results and theoretical calculations, the transition-state model for asymmetric cyclopropanation is proposed. A great synthetic value of the reaction investigated is exemplified by the total synthesis of constrained analogs of bioactive compounds, namely, enantiopure cyclic analog of phaclofen and cyclopropylphosphonate analogs of nucleotides.

scholarly journals Theoretical study on pegylation reaction mechanisms of IFN-α-2a, IFN-α-2b and IFN-β-1a

2017 ◽  
Vol 82 (7-8) ◽  
pp. 841-850
Author(s):  
Mohammad Taqavian ◽  
Daryoush Abedi ◽  
Fatemeh Zigheimat ◽  
Leila Zeidabadinejad
Keyword(s):  
Polyethylene Glycol ◽  
Reaction Mechanism ◽  
Dft Calculations ◽  
Transition State ◽  
Reaction Mechanisms ◽  
Theoretical Study ◽  
Computational Study ◽  
Single Transition ◽  
Experimental Works ◽  
Ab Initio And Dft

Ab initio and DFT calculations have been carried out to study the reaction mechanism between interferons (IFNs) ?-2a, ?-2b and ?-1a and polyethylene glycol (PEG) group. The calculations show that the mechanisms are concerted, in agreement with the results of experimental works. However, although it appears that there is one single transition state, the characteristics of its structure reveal a very synchronous reaction mechanism. The reactions are clearly exothermic and as well have feasible activation energies. Our computational study shows that the lowest transition state energies are related to Lys 134, His 34 and Met 1 of IFN-?-2a, IFN-?-2b and IFN-?-1a, respectively.

scholarly journals Theoretical Study of the Electronic Effects in the Intramolecular Ketene-Styrene [2+2] Cycloaddition

2019 ◽  
Vol 54 (4) ◽  
Author(s):  
Manuel Fernando Rubio ◽  
Federico Jiménez-Cruz ◽  
Guillermo Ramírez-Galicia
Keyword(s):  
Transition State ◽  
Theoretical Study ◽  
Positive Charge ◽  
Ring Structure ◽  
Experimental Results ◽  
Electronic Effects ◽  
Hartree Fock ◽  
Reaction Constant ◽  
Remote Substituent

DFT (B3LYP/6-31+G*) and post-Hartree-Fock (MP2/6-31+G*//B3LYP/6-31G*) calculations were carried out in order to explain the effect of a remote substituent in the intramolecular ketene-styrene [2+2] cycloaddition of p-substituted 2-methyl-7-arylhepta- 1,6-dien-1-one which produces the bicycle[3.1.1] or the bicycle [3.2.0] heptanones according to Bèlanger experimental results. The transition state geometries were found as an asynchronous process with a three-member ring structure and an incipient positive charge development. Kinetic and thermodynamic controls were proposed at B3LYP/6-31+G* to determine which product is most likely to form in a competence reaction. In addition, the value of the ρ experimental reaction constant was reproduced, ρ ~ -1.34.

Theoretical study on reaction mechanism of the vinyl radical with nitrogen atom

2004 ◽  
Vol 686 (1-3) ◽  
pp. 123-130 ◽  
Author(s):  
Yang Sun ◽  
Qi-yuan Zhang ◽  
Xi-cheng Ai ◽  
Jian-ping Zhang ◽  
Chia-chung Sun
Keyword(s):  
Reaction Mechanism ◽  
Nitrogen Atom ◽  
Theoretical Study ◽  
Vinyl Radical

Comparison of an intramolecular Michael-type addition with its intermolecular counterpart: an abinitio theoretical study

1989 ◽  
Vol 67 (12) ◽  
pp. 2173-2177 ◽  
Author(s):  
C. I. Bayly ◽  
F. Grein
Keyword(s):  
Transition State ◽  
Michael Addition ◽  
State Energy ◽  
Theoretical Study ◽  
Theoretical Calculations ◽  
Single Point ◽  
Basis Set ◽  
Energy Change ◽  
Transition State Geometry ◽  
Michael Type Addition

Abinitio theoretical calculations were carried out on the intramolecular addition of 3-ketopent-4-en-1-olate 1 to form 1-oxacyclohex-3-en-4-olate 2 (reaction I; Scheme 1) and the corresponding intermolecular Michael addition of methanolate to butenone forming 4-methoxybut-2-en-2-olate 4 (reaction II; Scheme 1). The calculations were carried out at the RHF level using an augmented 4-31G basis set; single point energies were then taken using the 6-31 + G* basis set. The overall energy change of the reaction in going from reactants to products is very similar for both reactions, with products being about 8.3 kcal/mol more stable than reactants; the major difference energetically between the two reactions is at the level of the transition state: the transition state energy for reaction I (intramolecular) is 6 kcal/mol higher than that for reaction II (intermolecular). The transition state geometry of reaction II conforms quite closely to the stereoelectronic requirements for a Michael addition, but that of reaction I is very distorted, reflecting significant compromises in the stereoelectronic requirements. Keywords: abinitio theoretical study, Michael-type addition, intramolecular, transition state.

Theoretical calculations of rate of NDMA formation from gramine

2013 ◽  
Vol 91 (4) ◽  
pp. 275-282
Author(s):  
F. Shojaie ◽  
M. Dehestani
Keyword(s):  
Reaction Mechanism ◽  
Transition State ◽  
Density Functional ◽  
Transition State Theory ◽  
Theoretical Calculations ◽  
State Theory ◽  
Stationary Points ◽  
Functional Theory ◽  
Molecule Reaction ◽  
Good Agreement

The first ab initio theoretical study is performed on the ion–molecule reaction of gramine (C11H14N2) with NO+ for the formation of N-nitrosodimethylamine (NDMA). The reaction mechanism is investigated using the B3LYP density functional theory level. The stationary points along the reaction energy profile have been calculated at the B3LYP/6-311+G(d,p) level of the theory in the gas phase and solution phase. In this work, an attempt is made to elucidate the mechanism and so is proposed the efficient reactive pathway for the reaction of gramine with NO+ step by step. A complete reaction mechanism has been established, and the temperature dependence of all rate constants between 23 and 65 °C are reported and analyzed in terms of transition state theory. The percentages of NDMA formation in the 23–65 °C temperature range have been calculated in aqueous solution by transition state theory. The results are in good agreement with experimental results.

Theoretical study of the ketonization reaction mechanism of acetic acid over SiO2

2009 ◽  
Author(s):  
Mendel Fleisher ◽  
E. Lukevics ◽  
L. Leite ◽  
D. Jansone ◽  
K. Edolfa ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Reaction Mechanism ◽  
Theoretical Study
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