Analysis of the proton nuclear magnetic resonance spectra of some strained benzocycloalkenes and benzocycloalkenediones. Effect of strain on proton--proton, spin--spin coupling constants

An analysis has been made of the high-resolution nuclear-magnetic-resonance spectrum given by the hydrogen nuclei of 2:3-dichloropropene-l and cisand trans 1:3-dichloropropene-1. The spectra at 40 Mc/s of the 1:3-dichloropropenes were analyzed by means of the theory for ABX 2 developed here; the 16·2 Mc/s spectra were analyzed according to the ABC 2 theory by means of a digital computer. It is concluded that the ‘long-range’ spin-spin coupling constants between hydrogen nuclei on carbon atoms 1 and 3 of the 1 : 3-dichloropropenes are of opposite sign to the remainder. A correlation of these results with earlier work on butene-1 by Alexander (1958) leads to analogous conclusions for this molecule also.

Download Full-text

An estimate of the spin–spin coupling constant, 1J(1H,13C), in gaseous benzene

Canadian Journal of Chemistry ◽

10.1139/v96-169 ◽

1996 ◽

Vol 74 (8) ◽

pp. 1524-1525 ◽

Cited By ~ 4

Author(s):

Ted Schaefer ◽

Guy M. Bernard ◽

Frank E. Hruska

Keyword(s):

Nuclear Magnetic Resonance ◽

Dielectric Constant ◽

Magnetic Resonance ◽

Coupling Constants ◽

Spin Coupling ◽

Coupling Constant ◽

Spin Coupling Constant ◽

Spin Coupling Constants ◽

Spin Spin Coupling ◽

Gaseous Benzene

An excellent linear correlation (r = 0.9999) exists between the spin–spin coupling constants 1J(1H,13C), in benzene dissolved in four solvents (R. Laatikainen et al. J. Am. Chem. Soc. 117, 11006 (1995)) and Ando's solvation dielectric function, ε/(ε – 1). The solvents are cyclohexane, carbon disulfide, pyridine, and acetone. 1J(1H,13C)for gaseous benzene is predicted to be 156.99(2) Hz at 300 K. Key words: spin–spin coupling constants, 1J(1H,13C) for benzene in the vapor phase; spin–spin coupling constants, solvent dielectric constant dependence of 1J(1H,13C) in benzene; benzene, estimate of 1J(1H,13C) in the vapor; nuclear magnetic resonance, estimate of 1J(1H,13C) in gaseous benzene.

Download Full-text

THE ANALYSIS OF NUCLEAR MAGNETIC RESONANCE SPECTRA: III. PYRIDINE AND DEUTERATED PYRIDINES

Canadian Journal of Chemistry ◽

10.1139/v57-196 ◽

1957 ◽

Vol 35 (12) ◽

pp. 1487-1495 ◽

Cited By ~ 60

Author(s):

W. G. Schneider ◽

H. J. Bernstein ◽

J. A. Pople

Keyword(s):

Nuclear Magnetic Resonance ◽

Magnetic Resonance ◽

High Resolution ◽

Chemical Shifts ◽

Coupling Constants ◽

Spin Coupling ◽

Calculated Spectrum ◽

Proton Resonance ◽

Nuclear Magnetic Resonance Spectra ◽

Spin Coupling Constants

The proton resonance spectra of pyridine, 2,6-pyridine-d2, 3-pyridine-d1, and 4-pyridine-d1 have been obtained for the pure liquids under conditions of high resolution. The spectra have been analyzed as proton groupings of AB2X2, AB2, perturbed ABX, and B2X2 respectively. The spin-coupling constants obtained from analysis of the simpler spectra of the deuterated molecules were used to suggest trial solutions for the analysis of the complicated AB2X2 spectrum of pyridine. A final set of chemical shifts and spin-coupling constants derived for pyridine give satisfactory agreement between the observed and calculated spectrum.

Download Full-text