ChemInform Abstract: SUBSTITUENT EFFECTS ON THE PROTON SPIN-SPIN COUPLING OF BENZENES WITH SIDE-CHAIN INTERACTING GROUPS

1973 ◽  
Vol 4 (37) ◽  
pp. no-no
Author(s):  
D. G. DE KOWALEWSKI ◽  
R. BUITRAGO ◽  
R. YOMMI
Keyword(s):  
Substituent Effects ◽  
Proton Spin ◽  
Spin Coupling ◽  
Side Chain ◽  
Spin Spin Coupling

The Molecular Structure of Allenes and Ketenes, XIII Correlations of Carbon-Proton Spin-Spin Coupling Constants in Allenes with ab initio STO-3G Overlap Populations

1979 ◽  
Vol 34 (1) ◽  
pp. 118-120 ◽  
Author(s):  
Wolfgang Runge
Keyword(s):  
Molecular Structure ◽  
Ab Initio ◽  
Substituent Effects ◽  
Proton Spin ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Proton Coupling ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling ◽  
Cl Atoms

Abstract It is shown that substituent effects on one-bond and long-range carbon-proton coupling constants in monosubstituted allenes parallel quantitatively ab initio STO-3G carbon 2s-hydrogen 1 s overlap populations, irrespectively of whether the substituents are bonded to the allenic skeleton via first-row (C, O) or second-row (Si, S, Cl) atoms.

Stereospecific Spin–Spin Coupling between Hydroxyl Protons and 19F Nuclei in o-, m- and p-Fluorophenol Derivatives. "Through-space" Interactions via the Hydrogen Bond

1975 ◽  
Vol 53 (7) ◽  
pp. 986-992 ◽  
Author(s):  
J. Brian Rowbotham ◽  
Murray Smith ◽  
Ted Schaefer
Keyword(s):  
Hydrogen Bond ◽  
Substituent Effects ◽  
Proton Exchange ◽  
Spin Coupling ◽  
Side Chain ◽  
Molecular Orbital Calculations ◽  
Coupling Mechanism ◽  
Fluorine Nucleus ◽  
Hydroxyl Protons ◽  
Spin Spin Coupling

Under conditions of slow intermolecular hydroxyl proton exchange 6JpOH,F < 0, 5JtransOH,F > 0, 5JcisOH,F < 0, 4JoOH,F < 0 in fluorophenol derivatives. 5JmOH,F is remarkably insensitive to intrinsic substituent effects, yields accurate values of conformational populations of m-fluorophenol derivatives and can be used to demonstrate a buttressing effect on the strength of the relatively weak [Formula: see text] hydrogen bond. 4JoOH,F displays a stereospecific dependence opposite to that of other couplings from a side-chain proton to a ring fluorine nucleus, is apparently very sensitive to the distance between proton and fluorine nucleus and is cited as an example of a negative through-space coupling mechanism. Approximate molecular orbital calculations give some support to the last suggestion.

Proton spin–spin coupling constants and intramolecular hydrogen bonding in bromine derivatives of 1,3-dihydroxybenzene

1976 ◽  
Vol 54 (14) ◽  
pp. 2228-2230 ◽  
Author(s):  
Ted Schaefer ◽  
J. Brian Rowbotham
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Proton Spin ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Hydroxyl Groups ◽  
Oh Groups ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling ◽  
Derivatives Of

The conformational preferences in CCl4 solution at 32 °C of the hydroxyl groups in bromine derivatives of 1,3-dihydroxybenzene are deduced from the long-range spin–spin coupling constants between hydroxyl protons and ring protons over five bonds. Two hydroxyl groups hydrogen bond to the same bromine substituent in 2-bromo-1,3-dihydroxybenzene but prefer to hydrogen bond to different bromine substituents when available, as in 2,4-dibromo-1,3-dihydroxybenzene. When the OH groups can each choose between two ortho bromine atoms, as in 2,4,6-tribromoresorcinol, they apparently do so in a very nearly statistical manner except that they avoid hydrogen bonding to the common bromine atom.

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