Substituent effects on the ionization and partitioning of p-(aminoethyl)phenols and structurally related compounds: Electrostatic effects dependent on conformation

2009 ◽  
Vol 98 (12) ◽  
pp. 4534-4544 ◽  
Author(s):  
Ravindra W. Tejwani ◽  
Terry R. Stouch ◽  
Bradley D. Anderson
Keyword(s):  
Substituent Effects ◽  
Electrostatic Effects ◽  
Related Compounds

Structure and Conformation of Photosynthetic Pigments and Related Compounds 9 On the Structure and Macrocycle Conformation of Two Copper(II) Rhodochlorin Derivatives and Two Related Rhodoporphyrins

1995 ◽  
Vol 50 (6) ◽  
pp. 969-981 ◽  
Author(s):  
Mathias O. Senge ◽  
Karin Ruhlandt-Senge ◽  
Shwn-Ji H. Lee ◽  
Kevin M. Smith
Keyword(s):  
Crystal Structure ◽  
Acetic Acid ◽  
Formic Acid ◽  
Photosynthetic Pigments ◽  
Dimethyl Ester ◽  
Substituent Effects ◽  
Crystal Data ◽  
Free Base ◽  
The Mean ◽  
Related Compounds

Crystal structure analyses of (rhodochlorinato-15-acetic trimethyl ester)copper(II) 3 and (31, 32-didehydro-rhodochlorinato-15-formic acid trimethyl ester)copper(II) 4 reveal intriguing multiple macrocycle conformations of the metallochlorins in the crystal. The observed conformations range from almost planar macrocycles to distorted macrocycles with individual atoms being displaced up to 0.72 Å from the mean plane. The nonplanar macrocycles show a S4-ruffled macrocycie distortion with significant distortions for the meso-carbons and tilting of the Cb- Cb axes. A comparison with the related free base porphyrins rhodoporphyrin-15- acetic acid trimethyl ester 5 and rhodoporphyrin dimethyl ester 6 shows that the conformational distortion is due to the mixing of metal and substituent effects, hydroporphyrin character, and packing forces. Crystal data: 3, monoclinic, P21, a = 12.096(4) Å, b - 14.307(4) Å, c = 22.343(9) Å , β = 104.94(4)°, Z = 4 (2 indep. mol.), R = 0.069 for 8141 reflections with I > 2.0σ(I); 4, triclinic, P 1, a = 10.528(3) Å . b - 10.646(4) Å, c = 34.026(13) Å, α = 89.81(4)°, β = 88.72(3)°, γ = 60.38(2)°, Z = 4 (4 indep. mol.). R = 0.073 for 9446 reflections with I > 2.5σ(I); 5, triclinic, P 1̄, a = 9.591(2) Å, b = 12.959(4) Å, c = 13.453(4) Å, α = 105.86(2)°, β = 92.67(2)°, γ = 96.12(2)°, Z = 2, R = 0.060 for 4990 reflections with I > 2.5 σ(I); 6, triclinic, P 1̄, a = 8.908(4) Å, b = 12.895(5) Å, c = 13.482(6) Å , α = 102.74(3)°, β = 90.38(4)°, γ = 91.84(3)°, Z = 2, R = 0.089 for 3369 reflections with I > 2.0σ(I).

Substituent Effects on Enthalpies of Formation of Nitrogen Heterocycles:  2-Substituted Benzimidazoles and Related Compounds

2006 ◽  
Vol 110 (7) ◽  
pp. 2535-2544 ◽  
Author(s):  
Lourdes Infantes ◽  
Otilia Mó ◽  
Manuel Yáñez ◽  
María Victoria Roux ◽  
Pilar Jiménez ◽  
...  
Keyword(s):  
Nitrogen Heterocycles ◽  
Substituent Effects ◽  
Enthalpies Of Formation ◽  
Related Compounds

Pyrimidine N-Oxides. II. The Synthesis of Some Amino- and Imino-pyrimidine N-Oxides and Related Compounds

1979 ◽  
Vol 32 (9) ◽  
pp. 2049 ◽  
Author(s):  
WB Cowden ◽  
NW Jacobsen
Keyword(s):  
Substituent Effects ◽  
Acid Oxidation ◽  
Peroxy Acid ◽  
Related Compounds

Substituent effects on the peroxy acid oxidation of some pyrimidine-2,4,6-triamines are reported together with the synthesis of new N'-methylpyrimidine N-oxides and a pyrimidine N,N'-dioxide.

ChemInform Abstract: Synthesis of Vinca Alkaloids and Related Compounds. Part 49. Aromatic Substituent Effects in the C-14 Epimerization.

ChemInform ◽  
2010 ◽  
Vol 22 (33) ◽  
pp. no-no
Author(s):  
I. MOLDVAI ◽  
A. VEDRES ◽  
C. JUN. SZANTAY ◽  
G. TOTH ◽  
C. SZANTAY
Keyword(s):  
Substituent Effects ◽  
Vinca Alkaloids ◽  
Aromatic Substituent ◽  
Related Compounds

scholarly journals Investigations of Substituent Effects by Nuclear Magnetic Resonance Spectroscopy and All-valence Electron Molecular Orbital Calculations. II. 4-Substituted α-Methylstyrenes and α-t-Butylstyrenes

1973 ◽  
Vol 51 (6) ◽  
pp. 915-926 ◽  
Author(s):  
Gordon K. Hamer ◽  
Ian R. Peat ◽  
W. F. Reynolds
Keyword(s):  
Chemical Shifts ◽  
Substituent Effects ◽  
Electron System ◽  
Resonance Spectroscopy ◽  
Molecular Orbital Calculations ◽  
Electronic Effects ◽  
Partial Explanation ◽  
Charge Densities ◽  
Related Compounds ◽  
Molecular Framework

Substituent-induced 1H chemical shifts (S.C.S.) for 19 4-substituted α-methyl- and α-t-butylstyrenes have been determined at infinite dilution in C6H12 and 13C S.C.S. have been determined for 0.4 M solutions in CCl4. S.C.S. are correlated with field and resonance substituent parameters and compared with charge densities determined by CNDO/2 MO calculations. The variation of S.C.S. with the dihedral angle, ρ, between phenyl and vinyl groups and the overall pattern of S.C.S. can be largely accounted for by a model of substituent effects based on field, resonance, and π polarization effects, with conjugative interactions varying as cos2ρ. Both 13C chemical shifts and charge densities indicate that the π polarization effect consists of two components: (1) a through-space polarization of the vinyl system by the polar C—X bond and (2) polarization of the entire conjugated styrene π electron system. However, significant deviations are noted for some of the 1H S.C.S. correlations. The CNDO/2 calculations indicate that these deviations are primarily due to electronic effects not predicted by the model outlined above. CNDO/2 calculations for related compounds provide a partial explanation by indicating that the magnitude of the field effect depends upon the nature of the molecular framework.

Electrostatic effects on ionization equilibria. 3-Substituted bicyclo[2,2,2]octane-1-carboxylic acids

1979 ◽  
Vol 44 (10) ◽  
pp. 2928-2945 ◽  
Author(s):  
Zdeněk Friedl ◽  
Jaroslav Hapala ◽  
Otto Exner
Keyword(s):  
Carboxylic Acids ◽  
Substituent Effects ◽  
Molecular Size ◽  
Geometrical Parameters ◽  
Electrostatic Effects ◽  
Ellipsoidal Cavity ◽  
Theoretical Predictions ◽  
Ionization Equilibria ◽  
The One

Nine 3-substituted (I-IX) and one 2-substituted (XI) bicyclo[2,2,2]octane-1-carboxylic acids were prepared as model compounds for verification of the electrostatic theory of substituent effects. On the one hand they are regular-shaped and suitable for calculations, on the other hand they allow to evaluate the role of the angle θ of the substituent dipole. The apparent pK values in 50% ethanol and 80% methyl cellosolve were correlated with σI constants (ρI 1.18 and 1.42, respectively) and compared with theoretical predictions based on the spherical and ellipsoidal cavity models. The agreement is very good with the new Ehrenson model but still satisfactory with some others not matching exactly the actual molecule shape. The substituent effects are resonably correlated with the substituent dipoles and with the geometrical parameters but exceptions are notable. Comparison with the previous results implies that the theory reproduces fairly the substituent effects in carboxylic acids of a given molecular size and not too unsymmetrical shape; the cavity model is, however, sufficiently flexible to compensate partly even for some non-electrostatic effects neglected by the basic theory.

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