Observations of nonadditive substituent effects on the dimethyl sulfoxide solution homolytic bond strengths of anthrylmethyl carbon-hydrogen bonds

1991 ◽  
Vol 113 (22) ◽  
pp. 8384-8388 ◽  
Author(s):  
M. J. Bausch ◽  
C. Guadalupe-Fasano ◽  
B. M. Peterson
Keyword(s):  
Hydrogen Bonds ◽  
Dimethyl Sulfoxide ◽  
Substituent Effects ◽  
Dimethyl Sulfoxide Solution ◽  
Bond Strengths ◽  
Carbon Hydrogen Bonds

Comparisons of nitrogen-hydrogen, carbon-hydrogen, oxygen-hydrogen, and sulfur-hydrogen heterolytic and homolytic bond strengths in aqueous and dimethyl sulfoxide solution

1991 ◽  
Vol 56 (26) ◽  
pp. 7191-7193 ◽  
Author(s):  
M. J. Bausch ◽  
R. Gostowski ◽  
C. Guadalupe-Fasano ◽  
D. Selmarten ◽  
A. Vaughn ◽  
...  
Keyword(s):  
Dimethyl Sulfoxide ◽  
Dimethyl Sulfoxide Solution ◽  
Bond Strengths

A concise synthesis of a highly substituted 6-(1H-benzimidazol-1-yl)-5-nitrosopyrimidin-2-amine: synthetic sequence and the molecular and supramolecular structures of one product and two intermediates

2018 ◽  
Vol 74 (6) ◽  
pp. 696-702 ◽  
Author(s):  
Justo Cobo ◽  
Daniel E. Vicentes ◽  
Ricaurte Rodríguez ◽  
Antonio Marchal ◽  
Christopher Glidewell
Keyword(s):  
Schiff Base ◽  
Hydrogen Bonds ◽  
Dimethyl Sulfoxide ◽  
Ring Closure ◽  
Private Communication ◽  
Efficient Synthesis ◽  
Electronic Polarization ◽  
Interatomic Distances ◽  
Dimethyl Sulfoxide Solution ◽  
Synthetic Sequence

A concise and efficient synthesis of 6-benzimidazolyl-5-nitrosopyrimidines has been developed using Schiff base-type intermediates derived from N 4-(2-aminophenyl)-6-methoxy-5-nitrosopyrimidine-2,4-diamine. 6-Methoxy-N 4-{2-[(4-methylbenzylidene)amino]phenyl}-5-nitrosopyrimidine-2,4-diamine, (I), and N 4-{2-[(ethoxymethylidene)amino]phenyl}-6-methoxy-5-nitrosopyrimidine-2,4-diamine, (III), both crystallize from dimethyl sulfoxide solution as the 1:1 solvates C19H18N6O2·C2H6OS, (Ia), and C14H16N6O3·C2H6OS, (IIIa), respectively. The interatomic distances in these intermediates indicate significant electronic polarization within the substituted pyrimidine system. In each of (Ia) and (IIIa), intermolecular N—H...O hydrogen bonds generate centrosymmetric four-molecule aggregates. Oxidative ring closure of intermediate (I), effected using ammonium hexanitratocerate(IV), produced 4-methoxy-6-[2-(4-methylphenyl-1H-benzimidazol-1-yl]-5-nitrosopyrimidin-2-amine, C19H16N6O2, (II) [Cobo et al. (2018). Private communication (CCDC 1830889). CCDC, Cambridge, England], where the extent of electronic polarization is much less than in (Ia) and (IIIa). A combination of N—H...N and C—H...O hydrogen bonds links the molecules of (II) into complex sheets.

Electrostatic effects on ionization equilibria: An MNDO study of proton and hydrogen transfer reactions of 4-fluorobutylamine

1990 ◽  
Vol 55 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Zdeněk Friedl ◽  
Stanislav Böhm
Keyword(s):  
Hydrogen Transfer ◽  
Substituent Effects ◽  
Radical Cations ◽  
Transfer Reactions ◽  
Protonated Forms ◽  
Minor Part ◽  
Bond Strengths ◽  
Ionization Equilibria ◽  
A Minor ◽  
Gas Phase Basicities

The relative enthalpies of proton transfer δ ΔH0and homolytic bond strengths δDH0(B-H+) were calculated by the MNDO method for the sp and ap conformers of 4-flurobutylamine. The data obtained, along with the experimental gas phase basicities, are compared with the values predicted by the electrostatic theory. It is shown that the substituent polar effects FD on the basicities of amines are predominantly due to interactions in their protonated forms (X-B-H+) and/or radical-cations (X-B+.), those in the neutral species (X-B) playing a minor part. A contribution, which is considerably more significant in the sp conformer than in the ap conformer, arises probably also from substituent effects on the homolytic bond strength DH0(B-H+.

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