scholarly journals Rotational Barrier and Quantification of Electron-Donating Substituent Effects: a Computational Study of para-Substituted Benzaldehydes

2020 ◽  
Vol 93 (2) ◽  
Author(s):  
Ali Hussain Yateem
Keyword(s):  
Computational Study ◽  
Substituent Effects ◽  
Rotational Barrier ◽  
Substituted Benzaldehydes

Carbon-13 N.M.R. chemical shifts and rotational barriers of para-substituted N,N-dimethylbenzamides

1978 ◽  
Vol 31 (12) ◽  
pp. 2615 ◽  
Author(s):  
CW Fong ◽  
SF Lincoln ◽  
EH Williams
Keyword(s):  
Chemical Shift ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Rotational Barrier ◽  
Rotational Barriers

The carbon-13 N.M.R. chemical shifts for a series of para-substituted N,N-dimethylbenzamides have been measured. The substituent induced 13C shifts have been examined by a dual substituent parameter (DSP) method using Hammett-type constants. The barriers to rotation have also been correlated with Hammett-type constants by the DSP method and related to 13C substituent induced shifts. Substituent effects of the bromomethyl, dibromomethyl and tribromomethyl groups have been examined by using the chemical shift and rotational barrier probes.

Computational study of substituent effects on the acidity, toxicity and chemical reactivity of bacteriostatic sulfonamides

2018 ◽  
Vol 81 ◽  
pp. 116-124 ◽  
Author(s):  
Catalina Soriano-Correa ◽  
Carolina Barrientos-Salcedo ◽  
Misaela Francisco-Márquez ◽  
C. Ignacio Sainz-Díaz
Keyword(s):  
Computational Study ◽  
Chemical Reactivity ◽  
Substituent Effects

Gas-phase structure, rotational barrier and vibrational properties of trimethylsilyl trifluoroacetate CF3C(O)OSi(CH3)3: An experimental and computational study

2010 ◽  
Vol 978 (1-3) ◽  
pp. 114-123 ◽  
Author(s):  
María E. Defonsi Lestard ◽  
María E. Tuttolomondo ◽  
Eduardo L. Varetti ◽  
Derek A. Wann ◽  
Heather E. Robertson ◽  
...  
Keyword(s):  
Gas Phase ◽  
Phase Structure ◽  
Computational Study ◽  
Rotational Barrier ◽  
Vibrational Properties ◽  
Gas Phase Structure

Computational study of substituent effects on gas-phase stabilities of Meisenheimer complexes

2015 ◽  
Vol 93 (12) ◽  
pp. 1327-1334 ◽  
Author(s):  
Kazuhide Nakata ◽  
Mizue Fujio ◽  
Hans-Ullrich Siehl ◽  
Yuho Tsuno
Keyword(s):  
Gas Phase ◽  
Narrow Range ◽  
Computational Study ◽  
Substituent Effects ◽  
Orbital Interaction ◽  
Conjugation System ◽  
Isodesmic Reactions ◽  
Meisenheimer Complexes ◽  
Stabilization Energies ◽  
Respective Species

The total stabilization energies (TSEs) and anion stabilization energies (ASEs) of ring-substituted (X-) Meisenheimer complexes featuring two NO2 groups in the ring were determined using appropriate isodesmic reactions. The structures and energies of respective species were calculated at the B3LYP/6–311+G(2d,p) level of theory. Ten series of substituent effects were examined by varying substituent Y, which is connected to the sp3 carbon of the ring. The substituent effects were successfully analyzed using an extended Yukawa–Tsuno equation, [Formula: see text]. The r− values for the TSEs were identical to those for the ASEs, whereas the s values for the TSEs were significantly different from those for the ASEs. This shows that the effect of neutral species contributes to the s values of the TSEs. The r− and s values for the ASEs of all Meisenheimer complexes were distributed in a narrow range because substituent Y was insulated from the π-conjugation system. The r− values were large and the s values were small. This shows that the r− and s values were independent of each other and that the extended three-term Yukawa–Tsuno equation was intrinsic for substituent-effect analyses of anions. Although the variation was not substantial, the change in the r− values was clearly explained by the orbital interaction between substituent Y and the π-conjugation system. The r− values exhibited a good correlation with the bond lengths between the ring and the 4-NO2 group among all Meisenheimer complexes and benzylic anions. These facts provide a physical meaning: the r− value is a parameter that reveals the degree of the additional π interactions between the electron-withdrawing substituents and the π-conjugation systems of the ring.

scholarly journals Diels-Alder reactions of vinylboranes: A computational study on the boron substituent effects

ARKIVOC ◽  
2003 ◽  
Vol 2003 (10) ◽  
pp. 556-565 ◽  
Author(s):  
María A. Silva ◽  
Silvina C. Pellegrinet ◽  
Jonathan M. Goodman
Keyword(s):  
Computational Study ◽  
Substituent Effects ◽  
Diels Alder
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