scholarly journals THE FREE RADICAL BRO MINA TION OF ETHYL PYRIDAZINES: THEORETICAL STUDIES

2014 ◽  
Vol 22 (22) ◽  
pp. 53-60
Author(s):  
I. A. ADEJORO ◽  
R. O. Ogede ◽  
C. U. Ibeji ◽  
O. O. Adeboye
Keyword(s):  
Free Radical ◽  
Rapid Method ◽  
Computational Methods ◽  
Theoretical Studies ◽  
Hartree Fock ◽  
Radical Bromination ◽  
Total Energies ◽  
Pyridazine Derivatives ◽  
Semi Empirical

Theoretical studies on free radical bromination by N-bromosuccinimide were carried out on a range of ethyl-3-methoxy-pyridazine derivatives. The investigations of these reactions performed, in order to develop a convenient and rapid theoretical means of predicting selectivity. The geometry optimizations of the total energies of the reactants and the products were calculated using Semi-empirical; AMI, MNDO, PM3 e Hartree Fock, HF3- 21 G computational methods. The calculation performed using PM3 Hamiltonian gave the best qualitative predictions, thus providing a rapid method for the selectivity of the reactions used in the synthesis of novel heterocyclic analogs of neurotransmitters.

Theoretical studies on the free-radical bromination of methyl-pyridazines in the synthesis of novel heterocyclic analogues of neurotransmitters

1996 ◽  
Vol 368 ◽  
pp. 235-243 ◽  
Author(s):  
Jeremy R. Greenwood ◽  
Graziano Vaccarella ◽  
Hugh R. Capper ◽  
Kenneth N. Mewett ◽  
Robin D. Allan ◽  
...  
Keyword(s):  
Free Radical ◽  
Theoretical Studies ◽  
Radical Bromination

Directing Bromination of Piperazine-2,5-diones

1995 ◽  
Vol 48 (7) ◽  
pp. 1379 ◽  
Author(s):  
TW Badran ◽  
CLL Chai ◽  
CJ Easton ◽  
JB Harper ◽  
DM Page
Keyword(s):  
Free Radical ◽  
Methyl Substituent ◽  
Radical Bromination ◽  
Acetyl Group

From intermolecular and intramolecular competition experiments, it has been established that, by comparison with an N-methyl substituent, an N-acetyl group deactivates glycine residues in piperazine-2,5-diones towards free-radical bromination. Combined with the ease of introduction and removal of N-acetyl substituents, the deactivating effect provides a method for regiocontrolled functionalization of these compounds.

Relation between Magnetic, Spectroscopic and Structural Properties of Binuclear Copper(II) Complexes of Pentadentate Schiff-base Ligand, Semi-empirical and ab-initio Calculations

2003 ◽  
Vol 58 (5-6) ◽  
pp. 363-372 ◽  
Author(s):  
Y. Elerman ◽  
H. Kara ◽  
A. Elmali
Keyword(s):  
Ab Initio ◽  
Coupling Constants ◽  
Antiferromagnetic Coupling ◽  
X Ray Diffraction ◽  
Hartree Fock ◽  
Ligand Orbital ◽  
Rhf Calculations ◽  
The Difference ◽  
Semi Empirical

The synthesis and characterization of [Cu2(L1)(3,5 prz)] (L1=1,3-Bis(2-hydroxy-3,5-chlorosalicylideneamino) propan-2-ol) 1 and of [Cu2(L2)(3,5 prz)] (L2=1,3-Bis(2-hydroxy-bromosalicylideneamino) propan-2-ol) 2 are reported. The compounds were studied by elemental analysis, infrared and electronic spectra. The structure of the Cu2(L1)(3,5 prz)] complex was determined by x-ray diffraction. The magnetochemical characteristics of these compounds were determined by temperaturedependent magnetic susceptibility measurements, revealing their antiferromagnetic coupling. The superexchange coupling constants are 210 cm−1 for 1 and 440 cm−1 for 2. The difference in the magnitude of the coupling constants was explained by the metal-ligand orbital overlaps and confirmed by ab-initio restricted Hartree-Fock (RHF) calculations. In order to determine the nature of the frontier orbitals, Extended Hückel Molecular Orbital (EHMO) calculations are also reported.

ChemInform Abstract: Free-Radical Bromination of Selected Organic Compounds in Water.

ChemInform ◽  
2010 ◽  
Vol 28 (23) ◽  
pp. no-no
Author(s):  
H. SHAW ◽  
H. D. PERLMUTTER ◽  
C. GU ◽  
S. D. ARCO ◽  
T. O. QUIBUYEN
Keyword(s):  
Free Radical ◽  
Organic Compounds ◽  
Radical Bromination

Stereoelectronic effects on chemoselectivity in the free radical bromination of arylcyclopropanes

1990 ◽  
Vol 112 (14) ◽  
pp. 5557-5562 ◽  
Author(s):  
James M. Tanko ◽  
Rosemal H. Mas ◽  
N. Kamrudin Suleman
Keyword(s):  
Free Radical ◽  
Stereoelectronic Effects ◽  
Radical Bromination

Gaussian basis sets for the atoms from K through Xe

2001 ◽  
Vol 79 (2) ◽  
pp. 121-123 ◽  
Author(s):  
R Centoducatte ◽  
E VR de Castro ◽  
F E Jorge
Keyword(s):  
Key Words ◽  
Ground State ◽  
Basis Sets ◽  
Gaussian Basis Sets ◽  
Hartree Fock ◽  
Generator Coordinate ◽  
Discretization Technique ◽  
Total Energies

An improved generator coordinate Hartree-Fock (IGCHF) method is used to generate Gaussian basis sets for the atoms from K (Z = 19) through Xe (Z = 54). The Griffin-Hill-Wheeler-HF equations are integrated using the integral discretization technique. The ground state HF total energies obtained by us are compared with those calculated with the original GCHF method and with other approaches reported in the literature. The largest difference between our energy values and the corresponding ones computed with a numerical HF method is equal to 6.003 mhartree for Kr (Z = 36).Key words: improved generator coordinate Hartree-Fock method, Gaussian basis sets, total energies.

scholarly journals Density functional tight binding: values of semi-empirical methods in an ab initio era

2014 ◽  
Vol 16 (28) ◽  
pp. 14368-14377 ◽  
Author(s):  
Qiang Cui ◽  
Marcus Elstner
Keyword(s):  
Density Functional Theory ◽  
Ab Initio ◽  
Density Functional ◽  
Tight Binding ◽  
Empirical Methods ◽  
Functional Theory ◽  
Hartree Fock ◽  
Semi Empirical

Semi-empirical (SE) methods are derived from Hartree–Fock (HF) or Density Functional Theory (DFT) by neglect and approximation of electronic integrals.

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