PROTON MAGNETIC RESONANCE SPECTRA OF D-GLUCOPYRANOSE POLYMERS

1965 ◽  
Vol 43 (10) ◽  
pp. 2652-2659 ◽  
Author(s):  
C. A. Glass
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Ring Current ◽  
Chemical Shifts ◽  
Deuterium Oxide ◽  
Anomeric Proton ◽  
Linear Polymers ◽  
Pyranose Ring ◽  
Glucose Derivatives ◽  
Magnetic Resonance Spectra

The proton magnetic resonance spectra of carbohydrates in deuterium oxide solution were obtained and considered with respect to probable conformation. The anomeric proton signal occurred at lowest field and was easily recognized. In the various glucose derivatives investigated, this signal occurred from 4.62 to 5.25 τ for equatorial protons and from 5.12 to 5.65 τ for axial protons. Within each of these ranges, the chemical shifts varied inversely with the electronegativity at the C1 site, as calculated by the technique of Gordy (1). Variable electronegativity at C1 accounts for the overlap of ranges for equatorial and axial protons, thereby bringing the n.m.r. data into agreement with assignment of the C1 chair form of the pyranose ring to the linear polymers of D-glucopyranose. The orientation of the glucopyranose rings in cyclodextrins is shown to preclude ring current effects, and the up-field chemical shifts of these materials are shown to be consistent with the C1 form.

Proton magnetic resonance spectra of 3,4-dehydroproline derivatives

1966 ◽  
Vol 19 (1) ◽  
pp. 115 ◽  
Author(s):  
LF Johnson ◽  
AV Robertson ◽  
WRJ Simpson ◽  
B Witkop
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Chemical Shifts ◽  
Deuterium Oxide ◽  
Methyl Esters ◽  
Amide Bond ◽  
Order Analysis ◽  
System A ◽  
Full Analysis ◽  
Magnetic Resonance Spectra

Slight changes in the chemical shifts of protons in 3,4-dehydroproline derivatives cause the appearance of their proton magnetic resonance spectra to change markedly, and this can be effected by taking one compound in two different solvents or by observing closely related derivatives in the same solvent. The explanation involves a previously undescribed type of deceptively simple coupling and the necessary conditions are discussed. A first-order analysis of the ABMXX' pattern for 3,4-dehydroprolinamide in deuterium oxide is given. A full analysis is made of the ABXX' and ABXY patterns for this amide in deuterium oxide and deuterochloroform respectively after deuterium exchange of the labile H2; a very large homoallylic coupling is required. Two conformations exist at 40� in solution for all N-benzyloxycarbonyl methyl esters of proline and its derivatives due to restricted rotation about the amide bond. Free rotation of the amide bond of corresponding N-acetyl and AT-benzoyl derivatives still occurs at -50�. The deceptively simple spectrum of N-benzyloxycarbonyl-2,5-dihydroxy-Δ3-pyrolne is discussed and that of its diacetate is analysed as an A2X2 system; a very small homoallylic coupling is required.

THE PROTON MAGNETIC RESONANCE SPECTRA AND TAUTOMERIC EQUILIBRIA OF ALDOSES IN DEUTERIUM OXIDE

1966 ◽  
Vol 44 (3) ◽  
pp. 249-262 ◽  
Author(s):  
R. U. Lemieux ◽  
J. D. Stevens
Keyword(s):  
Aqueous Solution ◽  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Chemical Shifts ◽  
Deuterium Oxide ◽  
Chair Conformation ◽  
Hydroxyl Group ◽  
Equatorial Orientation ◽  
Tautomeric Equilibria ◽  
Magnetic Resonance Spectra

The proton magnetic resonance spectra of D-xylose, D-lyxose, D-arabinose, D-ribose, D-glucose, D-mannose, and D-galactose were determined at 100 Mc.p.s. in deuterium oxide. The chemical shifts and structures of a number of ring protons in these compounds were determined either by spin-decoupling experiments or by synthesis of specifically deuterated compounds. The proton magnetic resonance parameters are shown to provide considerable information on the conformations and tautomeric equilibria for the sugars in aqueous solution. It is concluded that, for aldopyranoses in a chair conformation, the chemical shift of equatorial protons at a given position is virtually independent of configurational changes at other positions. However, an axial proton is shielded about 0.3 p.p.m. less by an axial hydroxyl group at a neighboring position than when the hydroxyl group is in an equatorial orientation. An axial hydroxyl group leads to deshielding of an opposing axial proton by about 0.35 p.p.m. By using the chemical shifts of the ring protons of β-D-xylopyranose and β-D-glucopyranose as reference point, the chemical shifts of protons in other pyranose structures could be anticipated to within a useful degree of accuracy.Evidence was obtained that D-ribose and 2-deoxy-D-ribose exist in aqueous solution both in the pyranose and in the furanose forms. None of the other pentoses showed readily detectable amounts of the furanose forms at equilibrium. Although D-allose does not give readily detectable amounts of the furanose forms when at equilibrium in aqueous solutions, D-altrose does. D-Talose showed only two forms, one of which was the β-pyranose structure.

Octahedral cobalt complexes in dipolar aprotic solvents. VIII. The proton magnetic resonance spectra of some octahedral cis- and trans-Bisethylenediaminecobalt(III) isomers in NN-dimethylformamide, NN-dimethyl-acetamide, and dimethyl sulphoxide

1967 ◽  
Vol 20 (1) ◽  
pp. 35 ◽  
Author(s):  
IR Lantzke ◽  
DW Watts
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Chemical Shifts ◽  
Deuterium Oxide ◽  
Dimethyl Sulphoxide ◽  
Aprotic Solvents ◽  
Similar Data ◽  
Dimethyl Acetamide ◽  
Dipolar Aprotic Solvents ◽  
Magnetic Resonance Spectra

The proton magnetic resonance spectra of a series of octahedral bisethylene-diaminecobalt(III) complexes in the dipolar aprotic solvents NN-dimethylformamide, NN-dimethylacetamide, and dimethyl sulphoxide have been examined. Resonances due to the protons attached to the nitrogen atoms of the ethylenediamine ligands are easily observed in these solvents, and their chemical shifts are reported, together with some similar data determined in deuterium oxide, and 95% sulphuric acid. The pattern of the nitrogen proton resonances is dependent on the stereo- chemistry of the complex. Using these differences in resonance, the cis configuration of some recently synthesized solvent complexes has been confirmed. The observed resonances are assigned to the particular protons in most cases.

Proton magnetic resonance studies at 220 MHz of alanine transfer RNA

1969 ◽  
Vol 47 (4) ◽  
pp. 480-484 ◽  
Author(s):  
Ian C. P. Smith ◽  
Tetsuo Yamane ◽  
R. G. Shulman
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Chemical Shifts ◽  
Transfer Rna ◽  
Magnetic Resonance Studies ◽  
The Common ◽  
Line Widths ◽  
Increasing Temperature ◽  
Magnetic Resonance Spectra

Proton magnetic resonance spectra at 220 MHz of alanine transfer RNA do not permit assignments of individual peaks due to each of the common bases; only a peak attributable to protons at position eight in adenine can be assigned with certainty. Measurements of the relative areas of proton magnetic resonance peaks due to the base and ribose-1′ protons indicate that the ribose moieties of tRNA are not involved in bonds stronger than those experienced by the bases. Proton magnetic resonance peaks attributable to the methyl and dihydro protons of the rare bases can be distinguished in the 220 MHz spectra; the variation of their line widths and chemical shifts with increasing temperature indicates that the rare bases are located in regions of the alanine transfer RNA molecule which are more highly organized than indicated by an open cloverleaf model.

Proton magnetic resonance spectra of some benzo[b]thiophens. An investigation of substituent effects in a heteroaromatic system

1968 ◽  
Vol 21 (7) ◽  
pp. 1853 ◽  
Author(s):  
B Caddy ◽  
M Martin-Smith ◽  
RK Norris ◽  
ST Reid ◽  
S Sternhell
Keyword(s):  
Magnetic Resonance ◽  
Long Range ◽  
Proton Magnetic Resonance ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Spin Coupling ◽  
Heteroaromatic System ◽  
Spin Spin Coupling ◽  
Magnetic Resonance Spectra

N.m.r. data for 19 5-substituted and 13 polysubstituted benzo[b]thiophens are tabulated. The influence of the substituents at C5 on the chemical shifts of H4 and H6 is discussed. Long-range interproton spin-spin coupling between H3 and H7, and between H2 and H6, is general in benzo[b]thiophens. The vicinal coupling J6,7 in 5-substituted benzo[b]thiophens varies directly and linearly with the electronegativity of the substituents at C5.

Protonenresonanz-Spektroskopie ungesättigter Ringsysteme I

1965 ◽  
Vol 20 (10) ◽  
pp. 948-956 ◽  
Author(s):  
Harald Günther
Keyword(s):  
Magnetic Resonance ◽  
Concentration Dependence ◽  
Proton Magnetic Resonance ◽  
Chemical Shifts ◽  
Electron System ◽  
Coupling Constants ◽  
Resonance Signal ◽  
Aromatic Character ◽  
Additional Support ◽  
Magnetic Resonance Spectra

The proton magnetic resonance spectra of 1.6-methano- and 1.6-oxido-cyclodecapentaene are described and analyzed in terms of chemical shifts and coupling constants. The results are discussed in connection with the structure and possible aromatic character of these compounds. Measurements of the concentration dependence of the chloroform resonance signal in solutions of both compounds give additional support for the presence of a delocalized 10 π-electron system.

The analysis of the proton magnetic resonance spectra of heteroaromatic systems. V. Diazanaphthalenes

1965 ◽  
Vol 18 (5) ◽  
pp. 707 ◽  
Author(s):  
PJ Black ◽  
ML Heffernan
Keyword(s):  
Carbon Tetrachloride ◽  
Magnetic Resonance ◽  
Long Range ◽  
Iterative Procedure ◽  
Proton Magnetic Resonance ◽  
Chemical Shifts ◽  
Direct Calculation ◽  
Coupling Constants ◽  
Dilute Solutions ◽  
Magnetic Resonance Spectra

The proton magnetic resonance spectra of the four isomeric diazanaphthalenes, quinoxaline, phthalazine, quinazoline, and cinnoline, all as dilute solutions in carbon tetrachloride and acetone, have been investigated at 100 Mc/s. The chemical shifts and coupling constants have been obtained by direct calculation or, where appropriate, by an iterative procedure. Long-range coupling constants between protons separated by five and six bonds have been observed.

A PROTON MAGNETIC RESONANCE STUDY OF N-BIS(2-HALOETHYL)AMINES

1965 ◽  
Vol 43 (6) ◽  
pp. 1792-1797 ◽  
Author(s):  
George R. Pettit ◽  
Joseph A. Settepani ◽  
Ralph A. Hill
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Nitrogen Mustard ◽  
Chemical Shifts ◽  
Deuterium Oxide ◽  
The Self ◽  
Magnetic Resonance Study ◽  
Complex Series ◽  
Condensation Reactions ◽  
Proton Magnetic Resonance Study

The proton magnetic resonance chemical shifts of N-bis(2-haloethyl)amine hydrohalide salts have been found useful for rapidly assessing organohalide composition. An important illustration of nitogen mustard reactivity was obtained by observing the p.m.r. response of N-bis(2-haloethyl)amine hydrohalide salts (in deuterium oxide) following neutralization. In general, the amines rapidly entered a complex series of intra- and inter-molecular reactions. Among the substances studied N-bis(2-fluoroethyl)amine was by far the most stable and remained essentially unchanged during a 7-day period. By contrast N-bis(2-iodoethyl)amine was completely transformed in less than 6 min. The self-condensation reactions of, for example, N-bis(2-chloroethyl)amine appear to be accompanied by transient formation of N-2-chloroethylaziridine (IIIb). The present investigation indicates that p.m.r. spectroscopy is a valuable technique for evaluating the course of nitrogen mustard self-condensation reactions.

Proton magnetic resonance spectra of indolizine and its methyl derivatives and aza analogues

1964 ◽  
Vol 17 (10) ◽  
pp. 1128 ◽  
Author(s):  
PJ Black ◽  
ML Heffernan ◽  
LM Jackman ◽  
QN Porter ◽  
GR Underwood
Keyword(s):  
Magnetic Resonance ◽  
Long Range ◽  
Iterative Procedure ◽  
Proton Magnetic Resonance ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Methyl Derivatives ◽  
Magnetic Resonance Spectra

The proton magnetic resonance spectra of indolizine, indolizine-1,3-d2, 1- and 2-methylindolizine, 2,3-, 2,5-, 2,6-, and 2,7-dimethylindolizine and 1-, 2-, and 3-azaindolizine have been determined at 100 and/or 60 Mc/s. Unequivocal assignments have been made to all protons and the coupling constants and chemical shifts for indolizine and its aza analogues have been obtained by an iterative procedure. Long-range coupling constants involving protons separated by five and six bonds have been observed.

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