Synthesis of Methyl-5,6,11,12-tetrahydrodibenzo[a,e]cyclooctenols and a conformational study by proton nuclear magnetic resonance

1983 ◽  
Vol 36 (3) ◽  
pp. 517 ◽  
Author(s):  
KE White ◽  
BJ Slater ◽  
SH Graham
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
Membered Ring ◽  
Proton Nuclear Magnetic Resonance ◽  
Boat Conformation ◽  
Geminal Proton ◽  
Twist Boat ◽  
Axial Site ◽  
Nuclear Magnetic

A series of methyl-5,6,11,12-tetrahydrodibenzo[a,e]cycloocten-5-ols were synthesized, and their conformations assigned by means of proton nuclear magnetic resonance. Placing substituents in three of the four available sites on the eight-membered ring enabled the chemical shifts of the geminal proton to be observed. It was found that the three sites have intrinsic chemical shifts. The compounds studied were found to populate a twist-boat conformation, with bulky substituents preferentially populating the axial site.

THE RELATIVE ACCEPTOR POWER OF BORON TRIHALIDES TOWARD ACETONITRILE BY PROTON NUCLEAR MAGNETIC RESONANCE MEASUREMENTS

1966 ◽  
Vol 44 (8) ◽  
pp. 899-902 ◽  
Author(s):  
J. M. Miller ◽  
M. Onyszchuk
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
Dipole Moments ◽  
Proton Nuclear Magnetic Resonance ◽  
Methyl Proton ◽  
Linear Relationships ◽  
Acceptor Activity ◽  
Nuclear Magnetic Resonance Spectra ◽  
Nuclear Magnetic

Proton nuclear magnetic resonance spectra of BF3, BCl3, and BBr3 adducts of acetonitrile have been measured in nitrobenzene solution. Single peaks were observed in each case and chemical shifts relative to tetramethylsilane decreased in the order BBr3 > BCl3 > BF3, suggesting that this is the order of acceptor activity toward acetonitrile. Linear relationships exist between methyl proton chemical shifts of CH3CN•BX3 and the heats of formation, dipole moments, and infrared vibrational shifts of the same or related adducts.

A Study of the Proton Nuclear Magnetic Resonance Spectra of Aryl and Mono- and Disubstituted N-Methylazoles

1973 ◽  
Vol 51 (14) ◽  
pp. 2315-2322 ◽  
Author(s):  
Richard Noel Butler
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
Structural Characteristics ◽  
Proton Nuclear Magnetic Resonance ◽  
Methyl Group ◽  
Nuclear Magnetic Resonance Spectra ◽  
Azole Ring ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

Proton n.m.r. spectra of 111 substituted azoles are compared. The influence of the azole ring on the chemical shifts of substituent phenyl protons is discussed. A correlation between N-methyl chemical shifts and the structural characteristics of the N-methyl group in mono- and disubstituted azoles is noted.

Identification of Polychlorinated Pyrenes and Pyrene-Addition Products Using Proton Nuclear Magnetic Resonance Techniques

1987 ◽  
Vol 41 (7) ◽  
pp. 1194-1199 ◽  
Author(s):  
David L. Ashley ◽  
Elizabeth R. Barnhart ◽  
Donald G. Patterson ◽  
Robert H. Hill
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Proton Nuclear Magnetic Resonance ◽  
Relaxation Rates ◽  
Spectral Parameters ◽  
Normal Orientation ◽  
Nmr Techniques ◽  
Nuclear Magnetic

Nuclear magnetic resonance (NMR) techniques are used to determine the chlorination pattern on a number of chlorinated pyrenes and pyrene-addition products. Determining chemical shifts, couplings, and longitudinal relaxation rates makes the unequivocal assignment of these molecules possible. Chlorination under the conditions described here were found to follow the normal orientation rules for pyrene. Spectral parameters obtained from these molecules are consistent enough to allow further application to unknown compounds. This should simplify assigning NMR spectra to other chlorinated pyrene standards.

Metal – Aminopolycarboxylic Acid Complexes. III. Studies of Lead(II) – Tetraethylenepentaamineheptaacetic Acid in Aqueous Solution by Proton Nuclear Magnetic Resonance Spectroscopy

1971 ◽  
Vol 49 (12) ◽  
pp. 2096-2102 ◽  
Author(s):  
Peter Letkeman ◽  
Donald T. Sawyer
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Electrostatic Interactions ◽  
Chemical Shifts ◽  
Ph Dependence ◽  
Proton Nuclear Magnetic Resonance ◽  
Resonance Spectroscopy ◽  
Carboxylate Groups ◽  
Nitrogen Bonds ◽  
Nuclear Magnetic

Proton nuclear magnetic resonance (n.m.r.) spectroscopy and the pH dependence of the chemical shifts of the nonlabile protons have been used to determine the preferred protonation sites in tetraethylenepentaamineheptaacetic acid (TPHA). The nitrogen atoms are protonated more readily than the carboxylate groups with the sequence of protonation dependent on electrostatic interactions. The 1:1 Pb(II)–TPHA complex which is not protonated for solution conditions from pH 10 to 14, has five metal–nitrogen bonds. The coordinate bonds are labile so that rapid interconversion between nonequivalent configurations produces an average configuration in which the protons of the acetate groups exhibit single n.m.r. peaks. Protonation of the complex probably occurs in three stages. From pH 10 to pH 8 the preferred protonation sites are the terminal nitrogen atoms with the attendant elimination of the metal–nitrogen bonds. Increasing the acidity to pH 4 causes all but the central nitrogen site to be protonated. Below pH 4 the central nitrogen atom becomes protonated and causes further unwrapping of the complex.

A proton nuclear magnetic resonance relaxation study of the glycine, alanine, and lactate complexes of gadolinium(III) in aqueous solution

1987 ◽  
Vol 65 (7) ◽  
pp. 1508-1512 ◽  
Author(s):  
R. Stephen Reid ◽  
Benjamin Podányi
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Membered Ring ◽  
Proton Nuclear Magnetic Resonance ◽  
Proton Relaxation ◽  
Carboxylate Group ◽  
Relaxation Rates ◽  
Spin Lattice ◽  
Resonance Spin ◽  
Nuclear Magnetic

The 1H nuclear magnetic resonance spin-lattice and spin–spin relaxation rate enhancements induced by the gadolinium(III) ion were measured in solutions of glycine, alanine, and sodium lactate containing different amounts of Gd(III). The proton relaxation rates in the Gd(III) complexes were calculated from these data, and were used to calculate metal–hydrogen atom distances. Comparison of these data with corresponding distances calculated from literature X-ray crystallographic data for model compounds shows that in the two amino acid complexes the Gd(III) ion is coordinated in a four-membered ring through the two oxygen atoms of the carboxylate group. By contrast, in the lactate complex coordination is via a five-membered ring involving one oxygen atom of the carboxylate group and the α-hydroxyl oxygen.

Sign in / Sign up

Export Citation Format

Share Document