Nuclear magnetic resonance studies. X. Determination of the thermodynamic parameters of the self-association of tricyclic aromatic aldehydes in solution

1967 ◽  
Vol 45 (3) ◽  
pp. 213-219 ◽  
Author(s):  
Gurudata ◽  
R. E. Klinck ◽  
J. B. Stothers
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Temperature Dependence ◽  
Thermodynamic Parameters ◽  
Aromatic Aldehydes ◽  
The Self ◽  
Kcal Mole ◽  
Magnetic Resonance Studies ◽  
Self Association

The temperature dependence of the formyl proton shieldings of 9-anthraldehyde and 9-phenanthraldehyde in chloroform solutions has been measured. Four concentrations in the range 0.5–5.0 mole % were examined over the temperature interval − 60 to + 90 °C. From these results, the enthalpies and entropies of formation have been estimated for the complex formed by the self-association of two aldehyde molecules. The calculations indicate the ΔH and ΔS values to be − 1.9 ± 0.3 kcal/mole and − 6 ± 1 e.u., respectively. These results are compared with other available data.

NUCLEAR MAGNETIC RESONANCE STUDIES: VIII. DETERMINATION OF THE THERMODYNAMIC PARAMETERS GOVERNING ASSOCIATIONS OF SUBSTITUTED BENZALDEHYDES IN TOLUENE SOLUTION

1966 ◽  
Vol 44 (1) ◽  
pp. 37-44 ◽  
Author(s):  
R. E. Klinck ◽  
J. B. Stothers
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Temperature Dependence ◽  
Chemical Shifts ◽  
Toluene Solution ◽  
Kcal Mole ◽  
Magnetic Resonance Studies ◽  
Substituted Benzaldehydes ◽  
Proton Chemical Shifts

The temperature dependence of the proton chemical shifts of four substituted benzaldehydes in toluene solution has been measured. From these results, estimates have been made of the enthalpies and entropies of formation of the stereospecific solute–solvent complexes which were previously shown to exist in these systems. These calculations indicate that the ΔH and ΔS values are −0.9 ± 0.2 kcal/mole and −4.9 ± 1.3 e.u., respectively. No correlation with substitution is apparent; the results are compared with other available data.

The self-association of Pyrrolid-2-one in acetonitrile and chloroform: An N.M.R. spectroscopic study

1972 ◽  
Vol 25 (1) ◽  
pp. 67 ◽  
Author(s):  
LF Blackwell ◽  
PD Buckley ◽  
KW Jolley ◽  
ID Watson
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
High Resolution ◽  
Magnetic Resonance Spectroscopy ◽  
Spectroscopic Study ◽  
Thermodynamic Parameters ◽  
Reasonable Agreement ◽  
The Self ◽  
Resonance Spectroscopy ◽  
Self Association

The self-association of pyrrolid-2-one has been studied in CDCl3 and CD3CN at several temperatures by the use of high resolution nuclear magnetic resonance spectroscopy. The enthalpies of self-association of the lactam in the two solvents have been measured and are in reasonable agreement with those for similar systems determined by the use of other methods. The enthalpy of salvation of pyrrolid-2-one in CHCl3 has also been measured. A discussion on the validity of the approximations used in the calculations of the thermodynamic parameters has been included.

Medium effects in nuclear magnetic resonance. VII. Vapor phase studies of hydrogen bonding in methanol and methanol–trimethylamine mixtures

1969 ◽  
Vol 47 (4) ◽  
pp. 625-629 ◽  
Author(s):  
A. D. H. Clague ◽  
G. Govil ◽  
H. J. Bernstein
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Vapor Phase ◽  
The Self ◽  
Resonance Spectroscopy ◽  
Kcal Mole ◽  
Medium Effects ◽  
Intermolecular Association ◽  
Self Association ◽  
Nuclear Magnetic

The self association of methanol, and the intermolecular association of methanol and trimethylamine have been examined in the vapor phase using nuclear magnetic resonance spectroscopy. Values of ΔH and ΔS for the two systems have been found to be −4.1 ± 0.5 kcal/mole and −17.5 ± 3 e.u., and −5.8 ± 0.7 kcal/mole and −22.6 ± 3 e.u., respectively.

Nuclear magnetic resonance studies on the self-association of adenosine 5′-triphosphate in aqueous solutions

1977 ◽  
Vol 55 (20) ◽  
pp. 3620-3630 ◽  
Author(s):  
Yiu-Fai Lam ◽  
George Kotowycz
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Association Constant ◽  
The Self ◽  
Relaxation Rates ◽  
Magnetic Resonance Studies ◽  
Average Value ◽  
Basic Solutions ◽  
Self Association

The self-association of adenosine 5′-triphosphate (ATP) in aqueous, basic solutions has been studied. The results indicate that the monomer–dimer–trimer equilibrium model for base association fits the data well, but so does a model which includes higher order species. This indicates that the ATP molecules in solution can undergo indefinite linear self-association. The average value of the association constant based on the 1H and 31P chemical shift measurements is 0.9 ± 0.3 M−1. Longitudinal relaxation rates for the H8, H1′, and H2 protons of ATP were obtained as a function of the nucleotide concentration. The analysis of the viscosity-corrected proton H2 data yields an association constant of 5.1 ± 1.3 M−1.

Variable Temperature Nuclear Magnetic Resonance Studies of Some Five-Membered Ring Chelate Complexes

1975 ◽  
Vol 53 (7) ◽  
pp. 1038-1045 ◽  
Author(s):  
William R. Cullen ◽  
Laurance D. Hall ◽  
John E. H. Ward
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Temperature Dependence ◽  
Significant Variation ◽  
Conformational Equilibrium ◽  
Variable Temperature ◽  
Membered Ring ◽  
Coupling Constants ◽  
Chelate Complexes ◽  
Magnetic Resonance Studies

The temperature dependence of the n.m.r. spectra of nine ditertiary arsine chelate complexes of formula (CH3)2AsC(3)(3′)C(4) (4′)As(CH3)2M(CO)3X has been studied (M = Mo, Cr; X = CO; M = Mn; X = halogen; (3), (3′), (4), (4′) = H, F, Si(CH3)3, CN; but not all combinations ). Significant variation in coupling constants, indicating a shift in the conformer populations, was found only for the CHFCF2 bridged Mn(CO)3Cl complex, the CH2CF2 bridged Mn(CO)3Cl complex, and the CHFCHF bridged Mo(CO)4 complex. In the last case the 3JHH coupling constants were used to estimate ΔH ∼ 1 kcal/mol and ΔS ∼ 3 e.u for the conformational equilibrium.

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