C13 SPLITTINGS IN SOME SUBSTITUTED BENZENES

1962 ◽  
Vol 40 (9) ◽  
pp. 1758-1762 ◽  
Author(s):  
H. M. Hutton ◽  
W. F. Reynolds ◽  
T. Schaefer
Keyword(s):  
Long Range ◽  
Electron Acceptors ◽  
Coupling Constants ◽  
Coupling Constant ◽  
Substituted Benzenes ◽  
First Order ◽  
Proton Coupling

C13 sidebands in the proton spectra of some symmetrically substituted benzenes have been used to obtain carbon–hydrogen coupling constants as well as proton coupling constants.A long-range carbon–hydrogen coupling constant has also been found. Substituents which act as electron acceptors in an inductive manner are found to increase the C13H coupling constants by as much as 20 c.p.s. The patterns of the sidebands are discussed and possible errors in first-order analyses are indicated.

Studies on the PMR Spectra of Oxetanes. VI 2-(3-Chlorophenyl)oxetane and 2-(2-Chlorophenyl)oxetane at 60 and 100 MHz

1974 ◽  
Vol 29 (12) ◽  
pp. 1902-1906 ◽  
Author(s):  
Jukka Jokisaari
Keyword(s):  
Long Range ◽  
Chemical Shifts ◽  
Methine Proton ◽  
Coupling Constants ◽  
Coupling Constant ◽  
Proton Proton ◽  
Temperature Range ◽  
Proton Coupling ◽  
Phenyl Proton ◽  
Pmr Spectra

The 100 MHz spectra of the phenyl protons in 2-(3-chlorophenyl) oxetane and 2-(2-chlorophenyl) oxetane have been analysed. The 60 MHz PMR chemical shifts and proton-proton coupling constants have been studied in the temperature range from -20 C to +80 °C. The chemical shifts were sensitive to temperature, while the coupling constants were not, except the long range 5Jm coupling constant between the methine proton and the meta positioned phenyl proton in 2-(2-chlorophenyl) oxetane.

Long-range spin–spin coupling constants between ring protons and aldehydic protons in some para-substituted benzaldehydes

1969 ◽  
Vol 47 (21) ◽  
pp. 4005-4010 ◽  
Author(s):  
S. S. Danyluk ◽  
C. L. Bell ◽  
T. Schaefer
Keyword(s):  
Long Range ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Coupling Constant ◽  
Proton Proton ◽  
Proton Coupling ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling ◽  
Coupling Mechanisms ◽  
Benzaldehyde Derivatives

The long-range proton–proton coupling constants between the ring protons and the aldehydic proton are reported for a series of para-substituted benzaldehyde derivatives. It was found that JoH,CHO < 0 and JmH,CHO > 0. Furthermore, JoH,CHO increases in magnitude as the electron donating power of the sub-stituent increases. A similar trend is observed forJmH,CHO but the ratio of the increase to the magnitude of JmH,CHO is much less than for JoH,CHO. A good correlation is obtained between JoH,CHO and the sub-stituent parameters of Swain and Lupton.The coupling constant data are discussed in terms of σ and π coupling mechanisms and it is concluded that σ electron mechanisms are dominant for both JoH,CHO and JmH,CHO.

Signs of long-range amino proton – ring proton coupling constants in N-ethyl-4-chloro-2-nitroaniline

1970 ◽  
Vol 48 (8) ◽  
pp. 1343-1345 ◽  
Author(s):  
T. Schaefer ◽  
R. Wasylishen
Keyword(s):  
Long Range ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Coupling Constant ◽  
Spin Coupling Constant ◽  
Proton Resonance ◽  
Ring Proton ◽  
Multiple Resonance ◽  
Proton Coupling ◽  
Spin Spin Coupling

In N-ethyl-4-chloro-2-nitroaniline there exists a measurable indirect spin–spin coupling constant of ±0.39 ± 0.03 Hz between the methylene protons and ring proton 6. The amino proton is coupled to ring protons 5 and 6 and also to the methylene protons. Consequently, although the amino proton resonance is broad due to incompletely relaxed coupling to 14N, normal multiple resonance experiments show that 5JmH,NH = 0.67 ± 0.03 Hz and 4JoH,NH = −0.35 ± 0.03 Hz.

Assignment of carbon-13 NMR spectra and sign determination of long range carbon-13—proton coupling constants with SPI

1974 ◽  
Vol 6 (8) ◽  
pp. 445-447 ◽  
Author(s):  
A. A. Chalmers ◽  
K. G. R. Pachler ◽  
P. L. Wessels
Keyword(s):  
Long Range ◽  
Nmr Spectra ◽  
Coupling Constants ◽  
Proton Coupling ◽  
Sign Determination

Concerning a relationship between long-range ring proton – methyl proton coupling constants and mobile bond order

1968 ◽  
Vol 46 (4) ◽  
pp. 654-656 ◽  
Author(s):  
D. J. Blears ◽  
S. S. Danyluk ◽  
T. Schaefer
Keyword(s):  
Linear Relationship ◽  
Long Range ◽  
Bond Order ◽  
Coupling Constants ◽  
Methyl Proton ◽  
Methyl Group ◽  
Potential Barriers ◽  
Proton Coupling ◽  
Induced Changes ◽  
Excitation Parameters

Long-range proton – methyl proton coupling constants in propene, mesitylene, 9-methylphenanthrene, and acenaphthene appear to be linearly related to the square of the mobile bond order between the carbon atoms bonded to the methyl group and the proton. However, substituent-induced changes in the charge on and hybridization state of the carbon atoms, in excitation parameters and in potential barriers to rotation of the methyl group, may also affect the coupling. Such changes must be considered in the application of a possible linear relationship.

Long-range coupling and conformation in some thienylmethylene and furfurylidene derivatives

1977 ◽  
Vol 30 (2) ◽  
pp. 357 ◽  
Author(s):  
GC Brophy ◽  
PJ Newcombe ◽  
RK Norris
Keyword(s):  
Aromatic Ring ◽  
Long Range ◽  
Coupling Constants ◽  
Coupling Constant ◽  
Vicinal Coupling Constant

The p.m.r, spectra of 12 2-thienylmethylene and furfurylidene derivatives are reported. The average conformation about the Ar-CHXY bond is deduced from the magnitude of the meta (and ortho) long-range benzylic coupling constants. In thiophens, conformations in which the benzylic hydrogen is in or near the plane of the aromatic ring and anti to the ring sulphur are preferred. In furans the hydrogen-in-plane conformations are again favoured. The signs of the meta and ortho benzylic coupling constants have been determined and are positive and negative respectively with respect to the vicinal coupling constant J3,4.

An Investigation of Long-range Proton–Proton Coupling Constants in Phenylacetylene Derivatives

1972 ◽  
Vol 50 (13) ◽  
pp. 2035-2040 ◽  
Author(s):  
C. J. MacDonald ◽  
G. K. Hamer ◽  
I. R. Peat ◽  
W. F. Reynolds
Keyword(s):  
Hyperfine Interaction ◽  
Long Range ◽  
Excellent Agreement ◽  
Quantitative Estimation ◽  
Theoretical Calculations ◽  
Experimental Results ◽  
Coupling Constants ◽  
Proton Proton ◽  
Proton Coupling

Signs and magnitudes of long-range coupling constants in three phenylacetylene derivatives have been determined. Values of the coupling constants are discussed in terms of the McConnell formulation and compared with results of MO–INDO–FPT calculations. Coupling constants are dominated by π contributions. Estimated values of hyperfine interaction constants for acetylene and methylacetylene groups are respectively QCC≡CH = −12 and QCC≡CCH = +12 G. The theoretical calculations are in excellent agreement with experimental results. Both approaches allow quantitative estimation of nine bond couplings in 4-vinylphenylacetylene.

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