Theoretical study of substituent effects on gas-phase stabilities of benzylic anions

2010 ◽  
Vol 23 (11) ◽  
pp. 1057-1065 ◽  
Author(s):  
Kazuhide Nakata ◽  
Mizue Fujio ◽  
Kichisuke Nishimoto ◽  
Yuho Tsuno
Keyword(s):  
Gas Phase ◽  
Theoretical Study ◽  
Substituent Effects

Theoretical study of substituent effects on the gas-phase stabilities of phenoxide anions

2012 ◽  
Vol 26 (2) ◽  
pp. 115-123 ◽  
Author(s):  
Kazuhide Nakata ◽  
Mizue Fujio ◽  
Kichisuke Nishimoto ◽  
Yuho Tsuno
Keyword(s):  
Gas Phase ◽  
Theoretical Study ◽  
Substituent Effects

Theoretical Study of Substituent Effects on the Gas-Phase Acidities of Benzoic and Phenylacetic Acids

ChemPlusChem ◽  
2013 ◽  
Vol 78 (9) ◽  
pp. 1099-1108 ◽  
Author(s):  
Kazuhide Nakata ◽  
Mizue Fujio ◽  
Kichisuke Nishimoto ◽  
Yuho Tsuno
Keyword(s):  
Gas Phase ◽  
Theoretical Study ◽  
Substituent Effects

THEORETICAL STUDY OF THE SUBSTITUENT EFFECTS ON THE REACTION ENTHALPIES OF THE ANTIOXIDANT MECHANISMS OF STOBADINE DERIVATIVES IN THE GAS-PHASE AND WATER

2013 ◽  
Vol 12 (02) ◽  
pp. 1250116 ◽  
Author(s):  
MEYSAM NAJAFI ◽  
MOHAMMAD NAJAFI ◽  
HOUSHANG NAJAFI
Keyword(s):  
Gas Phase ◽  
Theoretical Study ◽  
Substituent Effects ◽  
Partial Charge ◽  
Action Mechanisms ◽  
Dissociation Enthalpy ◽  
Proton Dissociation ◽  
Highest Occupied Molecular Orbital ◽  
Phase Water ◽  
Antioxidant Mechanisms

In this paper the reaction enthalpies of three antioxidant action mechanisms, HAT, SET–PT, and SPLET, for mono-substituted Stobadines were calculated in gas-phase and water. Results show that electron-withdrawing substituents increase the bond dissociation enthalpy (BDE), ionization potential (IP), and electron transfer enthalpy (ETE), while electron-donating ones cause a rise in the proton dissociation enthalpy (PDE) and proton affinity (PA). In comparison to gas-phase, water attenuates the substituent effect on all reaction enthalpies. Results show that IP and BDE values can be successfully correlated with the indolic N–H bond length after electron abstraction, R(N–H+•), and the partial charge on the indolyl radical nitrogen atom, q( N ). Furthermore, calculated IP and PA values for mono-substituted Stobadines show linear dependence on the energy of the highest occupied molecular orbital (E HOMO ) of studied molecules in the two environments. SPLET represents the thermodynamically preferred mechanism in water.

Theoretical study of substituent effects on the geometry and strain enthalpy in [2,2]paracyclophanes

2016 ◽  
Vol 9 (1) ◽  
pp. 6-13 ◽  
Author(s):  
Martin Michalík ◽  
Peter Poliak ◽  
Vladimír Lukeš
Keyword(s):  
Gas Phase ◽  
Density Functional ◽  
Theoretical Study ◽  
Substituent Effects ◽  
Functional Theory ◽  
Out Of Plane ◽  
Phenyl Rings ◽  
Strain Enthalpy ◽  
Substituent Constants ◽  
Repulsive Forces

Abstract The substituent effect on the geometry and strain enthalpy of [2,2]paracyclophane is theoretically investigated by density functional theory. Gas-phase calculations were performed for twenty distinct electron donating and electron withdrawing substituents. The largest out-of-plane distortion of phenyl rings is exhibited by —SCN and —CF3 groups. On the other hand, —OH, —CH3 and —F groups show the minimal deformation. The strain enthalpy for unsubstituted [2,2]paracyclophane associated with repulsive forces between phenyl units reached up to 118.5 kJ mol−1. Any substitution causes increase of the strain enthalpy value proportionally to the absolute values of Hammett para-substituent constants. Two separate linear dependences with similar slopes were obtained for monosubstituted as well as double symmetrically substituted derivatives.

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