An Investigation into the Nature of π-Inductive Effects: π Polarization Effects in Phenylalkanes with Polar or Charged Substituents

1973 ◽  
Vol 51 (11) ◽  
pp. 1857-1869 ◽  
Author(s):  
W. F. Reynolds ◽  
I. R. Peat ◽  
M. H. Freedman ◽  
J. R. Lyerla Jr
Keyword(s):  
Phenyl Ring ◽  
Polarization Effect ◽  
Chemical Shifts ◽  
Phenyl Group ◽  
Electron System ◽  
Mo Calculations ◽  
Polarization Effects ◽  
Electronic Distribution ◽  
Inductive Effects ◽  
Ph Dependent

pH dependent 13C chemical shifts for phenylglycine, phenylalanine, and phenylalanyl derivatives demonstrate that the electronic distribution of the phenyl group depends upon the distance of charged groups from the phenyl ring. The pattern of chemical shifts and the results of CNDO/2 MO calculations indicate that this is due to polarization of the phenyl π electron system. 13C chemical shifts and CNDO/2 calculations for α- and β-substituted phenylalkanes (substituent = NH3+, Cl or Br) provide further evidence for a π polarization effect.

The application of the Hammett equation to 13C N.M.R. spectrometry. VI. Remote ring effects in azobenzenes and stilbenes

1983 ◽  
Vol 36 (10) ◽  
pp. 2083 ◽  
Author(s):  
D Christoforou ◽  
DAR Happer
Keyword(s):  
Chemical Shifts ◽  
Phenyl Group ◽  
Resonance Interaction ◽  
Parameter Analysis ◽  
The Other ◽  
Hammett Equation ◽  
Resonance Effects ◽  
Inductive Effects

The 13C n.m.r. chemical shifts for the non-substituted rings of azobenzene, stilbene, 26 monosubstituted azobenzenes and 28 monosubstituted stilbenes are reported. The effects of substituents in one ring on the chemical shifts of the other have been interpreted in terms of their inductive and resonance effects by means of a dual substituent parameter analysis. The results show that inductive effects are transmitted to the remote ring from the meta and para positions with equal efficiencies and polarize the phenyl group independently of the rest of the molecule. Resonance interaction is greatest when the substituent is para to the azo or vinylene linking group and is relayed with greatest efficiency to the ortho and para carbons of the remote ring. The results of the study are compared with previously unreported data for the corresponding ring carbons of the ethyl arylazo- and arylethenyl-cinnamates, and with literature data on para-substituted biphenyls and terphenyls.

Does the Csp2—Csp3 barrier in ethylbenzene have a hyperconjugative component? An indirect experimental and theoretical approach

1994 ◽  
Vol 72 (8) ◽  
pp. 1780-1784 ◽  
Author(s):  
Ted Schaefer ◽  
Robert W. Schurko ◽  
Guy M. Bernard
Keyword(s):  
Chemical Shifts ◽  
Minor Component ◽  
Phenyl Group ◽  
Electron System ◽  
Proton Spin ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Total Magnitude ◽  
The Difference ◽  
A Minor

The proton chemical shifts and the proton spin–spin coupling constants are reported for 1-phenyl-1-butyne and 1-phenyl-1-pentyne dissolved in CS2/C6D12 and acetone-d6. The long-range coupling constants between the methylene and ring protons are used to derive the twofold barriers to internal rotation in these molecules. They are 0.5 ± 0.1 kJ/mol; the perpendicular conformer is the most stable, the one in which the C(3)—C(4) bond of the side chain lies in a plane perpendicular to the phenyl group. This energetic preference is assigned to the difference between C—C and C—H hyperconjugative interactions with the aromatic π electron system, the C—C interaction being larger. Comparison of the twofold components of the internal rotational barriers in biphenyl and diphenylacetylene, that in the latter amounting to 40% of that in the former, implies that the hyperconjugative component of the internal barrier in ethylbenzene is 1.2 ± 0.3 kJ/mol, a minor component of the total magnitude. Molecular orbital computations of the conformational energies of 1 -phenyl-1-butyne all agree that the perpendicular conformer has the lowest energy but only to the extent of 0.1 kJ/mol at most.

CNDO/2-Elektronenladungsdichten und 13C-chemische Verschiebungen von Phenylacetylenen / CNDO/2-Electron Charge Densities and 13C-Chemical Shifts of Phenylacetylenes

1972 ◽  
Vol 27 (12) ◽  
pp. 1772-1776 ◽  
Author(s):  
L Klasinc ◽  
J.V. Knop ◽  
H.-J Meiners ◽  
W Zeil
Keyword(s):  
Charge Transfer ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Electron System ◽  
Total Charge ◽  
Electron Charge ◽  
Substituted Benzenes ◽  
Charge Densities ◽  
Inductive Effects ◽  
Monosubstituted Benzenes

AbstractThe 13C FT NMR spectra of phenylacetylene (1), p-methoxyphenylacetylene (2), p-fluorophenyl-acetylene (3), p-chlorophenylacetylene (4), p-bromophenylacetylene (5), p-ethylphenylacetylene (6) and p-isopropylphenylacetylene (7) as well as of a number of monosubstituted benzenes have been measured. The 13 C-chemical shifts in these compounds are correlated with the total charge densities at the corresponding carbon atoms, calculated by the CNDO/2 method. The present results show that a simple additivity exists between 13C-chemical shifts in substituted benzenes, phenylacetylene and substituted phenylacetylenes and that practically no charge transfer between the linked sub-stituted phenyl and the ethinyl groups takes place. The interaction of the ethinyl substituent and the π-electron system can mainly be attributed to inductive effects.

The Bond N -Cl. A Spectroscopic (35Cl-NQR, IR) Investigation

1994 ◽  
Vol 49 (6) ◽  
pp. 695-702 ◽  
Author(s):  
B. Thimme Gowda ◽  
Alarich Weiss
Keyword(s):  
Phenyl Ring ◽  
Electron Distribution ◽  
Inductive Effect ◽  
Aqueous Media ◽  
Phenyl Group ◽  
Vibration Frequencies ◽  
Resonance Frequencies ◽  
35Cl Nqr ◽  
Cl Atoms ◽  
Cl Atom

Abstract Chlorine bound to nitrogen is an interesting oxidizing agent in aqueous, partial aqueous and non-aqueous media. One can assume that the oxidizing action of the chlorine depends on the polarization of the Cl atom in the bond N -Cl which will depend on the electron distribution in the ligands R and R″ of the configuration R -NCl -CO -R″. 17 compounds were synthesized with R = substituted phenyl radical C6H5-y Xy, X = Cl, NO2, R″ = CH2Cl. The 35Cl NQR frequencies are observed in the range 52 to 54 MHz (T = 77 K) for the Cl(N) 34 to 37 MHz for the phenyl chlorines and the CH2Cl group. Their temperature dependence was followed up to 300 K. Therefrom the assignment of the resonance to certain Cl-atoms in the molecules is possible. Generally, the substitution of a negative substituent X (Cl, NO2) in the phenyl ring raises the resonance frequencies; the influence of the CH2Cl group on the N -Cl bond is weak. Strong is the influence of the carbonyl group on the N -C l bond. The IR group frequencies ν(C = O) are found in the range 1680 ≤ ν (C = O)/ cm−1≤ 1717, shifted up by ≤ 20 cm−1 compared to the corresponding acetamide R ⎯ NH ⎯CO ⎯ R″. Influence of the phenyl ring substitution on ν (C = O) does not follow a simple law of inductive effect. Also a correlation between the vibration frequencies of the N ⎯ Cl group and the phenyl group substitution is not found.

scholarly journals pH-Dependent Piecewise Linear Correlation of 1H,31P Chemical Shifts: Application in NMR Identification of Nerve Agent Metabolites in Urine Samples

2018 ◽  
Vol 90 (14) ◽  
pp. 8495-8500 ◽  
Author(s):  
Harri Koskela ◽  
Boban Andjelkovic ◽  
Annette Pettersson ◽  
Marja-Leena Rapinoja ◽  
Marja-Leena Kuitunen ◽  
...  
Keyword(s):  
Linear Correlation ◽  
Chemical Shifts ◽  
Piecewise Linear ◽  
Nerve Agent ◽  
Urine Samples ◽  
Ph Dependent ◽  
Nmr Identification

Semiempirische SCF-LCAO-MO-Rechnungen als Zuordnungshilfe für 13C-chemische Verschiebungen / Semiempirical SCF-LCAO-MO-calculations as an Aid for the 13C-shift Determination

1975 ◽  
Vol 30 (9) ◽  
pp. 1185-1187 ◽  
Author(s):  
H. Sterk ◽  
H. W. Schmidt
Keyword(s):  
Charge Density ◽  
Chemical Shifts ◽  
Mo Calculations ◽  
Linear Relationships ◽  
Lcao Mo

It has been shown that charge density- and bondorder values in different linear relationships can build up a basis for the calculation of 13C-chemical shifts. This could be an aid for the assignement of different 13C signals

Spectroscopic Studies with N-Chloroarylsulphonamides: IR and 1H, 13C and 23Na Nmr Spectra of Sodium Salts of N-Chloro-Mono- and Di-Substituted-Benzenesulphonamides, 4-X-C6H4SO2NANCl (X = H; CH3; C2H5; F; Cl; Br; I or NO2) and i-X, j-YC6H3SO2NANCl (i-X, j-Y = 2,3-(CH3)2; 2,4-(CH3)2; 2,5-(CH3)2; 2-CH3, 4-Cl; 2-CH3, 5-Cl; 3-CH3, 4-Cl; 2,4-Cl2 or 3,4-Cl2)

2003 ◽  
Vol 58 (1) ◽  
pp. 51-56 ◽  
Author(s):  
◽  
J. D. D’Souza ◽  
B. H. Arun Kumar
Keyword(s):  
Solid State ◽  
Chemical Shift ◽  
Infrared Spectra ◽  
Phenyl Ring ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Spectroscopic Studies ◽  
Sodium Salts ◽  
Experimental Chemical Shift ◽  
23Na Nmr

In an effort to introduce N-chloroarylsulphonamides of different oxydising strengths, sixteen sodium salts of N-chloro-mono- and di-substituted benzenesulphonamides of the configuration, 4- X-C6H4SO2NaNCl (where X = H; CH3; C2H5; F; Cl; Br; I or NO2) and i-X, j-YC6H3SO2NaNCl (where i-X, j-Y = 2,3-(CH3)2; 2,4-(CH3)2; 2,5-(CH3)2; 2-CH3,4-Cl; 2-CH3,5-Cl; 3-CH3,4-Cl; 2,4- Cl2 or 3,4-Cl2) are prepared, characterized through their infrared spectra in the solid state and NMR spectra in solution. The υN-Cl frequencies vary in the range 950 - 927 cm−1. Effects of substitution in the benzene ring in terms of electron donating and electron withdrawing groups have been considered, and conclusions drawn. The chemical shifts of aromatic protons and carbon-13 in all the N-chloroarylsulphonamides have been calculated by adding substituent contributions to the shift of benzene. Considering the approximation employed the agreement between the calculated and experimental chemical shift values for different protons or carbon-13 is quite good. Effects of phenyl ring substitution on chemical shift values of both 1H and 13C are also graphically represented in terms of line diagrams.

Substituent-induced chemical shifts (SCS) by the phenyl group in sterically congested styrene derivatives

1993 ◽  
Vol 31 (4) ◽  
pp. 388-393 ◽  
Author(s):  
Rudolf Knorr ◽  
David S. Stephenson ◽  
Petra Böhrer ◽  
Thi-Phung Hoang
Keyword(s):  
Chemical Shifts ◽  
Phenyl Group ◽  
Styrene Derivatives

Protonenresonanz-Spektroskopie ungesättigter Ringsysteme I

1965 ◽  
Vol 20 (10) ◽  
pp. 948-956 ◽  
Author(s):  
Harald Günther
Keyword(s):  
Magnetic Resonance ◽  
Concentration Dependence ◽  
Proton Magnetic Resonance ◽  
Chemical Shifts ◽  
Electron System ◽  
Coupling Constants ◽  
Resonance Signal ◽  
Aromatic Character ◽  
Additional Support ◽  
Magnetic Resonance Spectra

The proton magnetic resonance spectra of 1.6-methano- and 1.6-oxido-cyclodecapentaene are described and analyzed in terms of chemical shifts and coupling constants. The results are discussed in connection with the structure and possible aromatic character of these compounds. Measurements of the concentration dependence of the chloroform resonance signal in solutions of both compounds give additional support for the presence of a delocalized 10 π-electron system.

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