13C Chemical shifts for 4-substituted phenylvinyl ethers, sulfides, and selenides: evidence concerning the relative abilities of O, S, and Se to transmit electronic effects

1977 ◽  
Vol 55 (3) ◽  
pp. 536-540 ◽  
Author(s):  
William F. Reynolds ◽  
Robert A. McClelland
Keyword(s):  
Chemical Shifts ◽  
Substituent Effects ◽  
Electronic Effects ◽  
13C Chemical Shifts ◽  
Link Group ◽  
Relative Ability ◽  
Link Atom

13C chemical shifts for β carbons of 4-substituted phenylvinyl ethers, sulfides, and selenides plus previous data for styrenes indicate that the relative ability of link groups to transmit electronic effects between conjugative groups is S > Se ≈ — > O (where — refers to no link group, i.e. styrene). However, marked deviations from additivity are noted for C(1) chemical shifts which may indicate that O deactivates the ring to electronic substituent effects while S and Se activate the ring. If this explanation is valid then the actual ability of the link atom to transmit electronic effects is — > O > S > Se.

scholarly journals Effects of substituents on the 1H-NMR chemical shifts of 3-methylene-2-substituted-1, 4-pentadienes

2003 ◽  
Vol 68 (7) ◽  
pp. 525-534 ◽  
Author(s):  
Natasa Valentic ◽  
Gordana Uscumlic
Keyword(s):  
Chemical Shifts ◽  
Substituent Effects ◽  
Electronic Effects ◽  
Resonance Effects ◽  
Charge Densities ◽  
Linear Free Energy ◽  
Energy Relationships ◽  
Consistent Picture ◽  
Vinyl Group ◽  
Proton Chemical Shifts

The principle of linear free energy relationships was applied to the 1H chemical shifts of the ?-vinyl proton atoms of 3-methylene-2-substituted-1,4-pentadienes. The correlations of the proton chemical shifts with Swain and Lupton substituent parameters provide a mutually consistent picture of the electronic effects in these compounds. The overall pattern of proton chemical shifts can be largely accounted for by a model of substituent effects based on field, resonance and ? polarization effects. Owing to the particular geometric arrangement of the vinyl group in 3-methylene-2-substituted-1,4-pentadienes, the ?-vinyl protons HB and HC have different sensitivities to polar and resonance effects. The different sensitivities of the 1H chemical shifts to resonance effects reveals some effects not predicted by the model outlined above. Evidence is presented that demonstrates that both the 1H and 13C chemical shifts for these compounds reflect their ground-state charge densities.

scholarly journals Substituenteneinflüsse auf die 13C–NMR-chemischen Verschiebungen cis- und trans-konfigurierter Trimethincyanine / Substituent Effects on the 13C NMR Chemical Shifts of Trimethincyanines with cis and trans Configuration

1976 ◽  
Vol 31 (12) ◽  
pp. 1641-1645 ◽  
Author(s):  
Walter Grahn
Keyword(s):  
13C Nmr ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Electron Systems ◽  
Coupling Constant ◽  
Electronic Effects ◽  
Nmr Chemical Shifts ◽  
Monosubstituted Benzenes ◽  
Cis And Trans ◽  
C Nmr

The 13C NMR chemical shifts of fifteen 6 substituted 2,3-dihydro-1,4-diazepinium salts (cis trimethincyanines) (1) and twelve 2 substituted bis(dimethylamino)trimethinium salts (trans trimethincyanines) (2) have been determined. A comparison of the substituentinduced shifts (13C SCS) of 1 and 2 allows no distinction between steric and electronic effects. In the three 6 п-electron systems 1, 2 and monosubstituted benzenes the 13C SCS are similar for the substituent bearing carbon atoms. A surprisingly large 4JFCCNC coupling constant has been observed.

Substituent effects on 13C chemical shifts

1972 ◽  
Vol 7 (4) ◽  
pp. 364-369 ◽  
Author(s):  
William B Smith ◽  
Dennis L Deavenport
Keyword(s):  
Chemical Shifts ◽  
Substituent Effects ◽  
13C Chemical Shifts

scholarly journals Transmission of Substituent Effects through Oxygen and Sulfur Atoms. II.13C Chemical Shifts of Ring-Substituted Phenyl Vinyl Ethers and Sulfides

1973 ◽  
Vol 46 (5) ◽  
pp. 1422-1425 ◽  
Author(s):  
Okitsugu Kajimoto ◽  
Masaru Kobayashi ◽  
Takayuki Fueno
Keyword(s):  
Chemical Shifts ◽  
Substituent Effects ◽  
Vinyl Ethers ◽  
13C Chemical Shifts ◽  
Phenyl Vinyl

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.

Unusual conformationally dependent substituent effects upon the 13C chemical shifts of β alkyl carbons of phenylalkanes.

1976 ◽  
Vol 17 (51) ◽  
pp. 4671-4674 ◽  
Author(s):  
W.F. Reynolds ◽  
R.H. Kohler ◽  
G.K. Hamer
Keyword(s):  
Chemical Shifts ◽  
Substituent Effects ◽  
13C Chemical Shifts

Substituent effects on 13C-15N spin couplings and 13C chemical shifts in benzenediazonium ions

1986 ◽  
Vol 27 (1) ◽  
pp. 11-14 ◽  
Author(s):  
T. Axenrod ◽  
X.H. Huang ◽  
C. Watnick
Keyword(s):  
Chemical Shifts ◽  
Substituent Effects ◽  
13C Chemical Shifts
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