Carbon-13 nmr shifts and C—H coupling constants of deoxybenzoins and related acetophenones

1981 ◽  
Vol 59 (15) ◽  
pp. 2266-2282 ◽  
Author(s):  
Hem Chandra Jha ◽  
Fritz Zilliken ◽  
Werner Offermann ◽  
Eberhard Breitmaier
Keyword(s):  
Hydrogen Bonding ◽  
Chemical Shifts ◽  
Carbonyl Oxygen ◽  
Coupling Constants ◽  
Structural Variations ◽  
Naturally Occurring ◽  
Internal Hydrogen ◽  
Benzene Rings ◽  
Substitutional Saturation

13C Chemical shifts and resolved carbon–proton couplings of 39 deoxybenzoins and 11 acetophenones, most of which have naturally occurring substitution patterns, are assigned. Individual benzene rings turned out to have typical parameters not affected by structural variations in the rest of the molecule. Due to substitutional saturation, however, these benzenoid carbon shifts markedly deviate from increment additivity. A few trends of these deviations are described. Phenolic hydrogens, fixed between hydroxyl and carbonyl oxygen due to internal hydrogen bonding, are shown to give rise to additional carbon-splittings.

scholarly journals Focal Point Evaluation of Energies for Tautomers and Isomers for 3-Hydroxy-2-Butenamide: Evaluation of Competing Internal Hydrogen Bonds of Types -OH…O=, -OH…N, -NH…O=, and CH…X (X=O and N)

Molecules ◽  
2021 ◽  
Vol 26 (9) ◽  
pp. 2623
Author(s):  
Zikri Altun ◽  
Erdi Bleda ◽  
Carl Trindle
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Focal Point ◽  
Noncovalent Interactions ◽  
Carbonyl Oxygen ◽  
Relative Strength ◽  
Basis Sets ◽  
Structural Variations ◽  
Internal Hydrogen ◽  
Correlation Consistent

The title compound is a small molecule with many structural variations; it can illustrate a variety of internal hydrogen bonds, among other noncovalent interactions. Here we examine structures displaying hydrogen bonding between carbonyl oxygen and hydroxyl H; between carbonyl oxygen and amino H; hydroxyl H and amino N; hydroxyl O and amino H. We also consider H-bonding in its tautomer 2-oxopropanamide. By extrapolation algorithms applied to Hartree-Fock and correlation energies as estimated in HF, MP2, and CCSD calculations using the cc-pVNZ correlation-consistent basis sets (N = 2, 3, and 4) we obtain reliable relative energies of the isomeric forms. Assuming that such energy differences may be attributed to the presence of the various types of hydrogen bonding, we attempt to infer relative strengths of types of H-bonding. The Atoms in Molecules theory of Bader and the Local Vibrational Modes analysis of Cremer and Kraka are applied to this task. Hydrogen bonds are ranked by relative strength as measured by local stretching force constants, with the stronger =O…HO- > NH…O= > -OH…N well separated from a cluster > NH…O= ≈ >NH…OH ≈ CH…O= of comparable and intermediate strength. Weaker but still significant interactions are of type CH…N which is stronger than CH…OH.

Proton Magnetic Resonance Spectra of Some Amphetamines and Related Compounds and Observations on Rotamer Populations

1971 ◽  
Vol 49 (19) ◽  
pp. 3143-3151 ◽  
Author(s):  
K. Bailey ◽  
A. W. By ◽  
K. C. Graham ◽  
D. Verner
Keyword(s):  
Hydrogen Bonding ◽  
Phenyl Ring ◽  
Proton Magnetic Resonance ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Side Chain ◽  
Amino Group ◽  
Ortho Position ◽  
Electronic Effects ◽  
Related Compounds

Data from the p.m.r. spectra of β-amino-, β-aminohydrochloride-, β-hydroxy-, and β-nitro-α-phenyl-propanes having methyl or methoxy substituants on the phenyl ring (37 compounds in all) are presented. The α and β protons of the side-chain give a pattern usually analyzable as ABX. The data are discussed in terms of correlations of coupling constants and chemical shifts with electronegativity of the substituent groups, steric and electronic effects, and apparent changes in rotamer populations. Hydrogen-bonding between the amino group of amphetamines and a methoxyl function at the ortho position in the phenyl ring is indicated for the salts but not the free bases.

PREFERRED RESIDENCE CONFORMATIONS OF DIASTEREOISOMERIC α–β AMINO ALCOHOLS: AN N.M.R. STUDY OF THE EPHEDRINES

1961 ◽  
Vol 39 (12) ◽  
pp. 2536-2542 ◽  
Author(s):  
J. B. Hyne
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Hydrogen Bonding ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
Amino Alcohols ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Spin Coupling Constants ◽  
Nuclear Magnetic

Nuclear magnetic resonance spectral results including chemical shifts, anisotropy effects, spin coupling constants, and hydrogen bonding phenomena are presented for the diastereoisomeric pair of α–β amino alcohols (−)-ephedrine and (+)-Ψ-ephedrine. The results are shown to be in keeping with the existence of a preferred residence conformation for each of the diastereoisomers.

A One- and Two-Dimensional 1H and 13C N.M.R. Study of Some Lichen Triterpenoids of the Pyxinol Group

1990 ◽  
Vol 43 (2) ◽  
pp. 411 ◽  
Author(s):  
AL Wilkins ◽  
JA Elix ◽  
AA Whitton
Keyword(s):  
Hydrogen Bonding ◽  
Hydroxy Group ◽  
Furan Ring ◽  
Chemical Shifts ◽  
Carbonyl Oxygen ◽  
Ring System ◽  
Acetoxy Group ◽  
Two Dimensional ◽  
Complete Assignment

A complete assignment of the 13C and 1H n.m.r. resonances of the lichen triterpenoids, pyxinol, 3,25-di-O-acetylpyxinol and 3,12,25-tri-O-acetylpyxinol has been achieved by using a combination of one- and two-dimensional n.m.r. data and T1 values. Hydrogen bonding between the 12β- hydroxy group and the carbonyl oxygen of the 25-acetoxy group of 3,25- di-O-acetylpyxinol leads to the furan ring system adopting a� conformation different from that adopted by 25-hydroxy analogues, hence differing chemical shifts are observed for some of the carbons of rings C and D and the furan ring.

scholarly journals Secondary structure of hyaluronate in solution. A 1H-n.m.r. investigation at 300 and 500 MHz in [2H6]dimethyl sulphoxide solution

1984 ◽  
Vol 220 (1) ◽  
pp. 197-205 ◽  
Author(s):  
J E Scott ◽  
F Heatley ◽  
W E Hull
Keyword(s):  
Secondary Structure ◽  
Hydrogen Bonds ◽  
Oxygen Atom ◽  
Glucuronic Acid ◽  
Chondroitin Sulphate ◽  
Chemical Shifts ◽  
Heparan Sulphate ◽  
Carbonyl Oxygen ◽  
Dimethyl Sulphoxide ◽  
Coupling Constants

The 1H-n.m.r. spectra of solutions in [2H6]dimethyl sulphoxide of the sodium salts of tetra-, hexa- and octa-saccharides prepared from hyaluronate by testicular-hyaluronidase digestion were examined at 300 and 500 MHz. The signals from hydroxy groups at positions 2 and 3 in the glucuronic acid moiety were assigned. Their chemical shifts and associated temperature-dependencies, as well as their coupling constants, depended on whether or not the uronic acid was at the non-reducing end. Deviations from the ‘normal’ pattern of hydroxy-group proton n.m.r. behaviour were attributable to participation in hydrogen bonds, either to the acetamido carbonyl oxygen atom or the pyranose ring oxygen atom of neighbouring N-acetylhexosamine moieties. A secondary structure, containing four different hydrogen bonds per trisaccharide unit of glucuronsyl-hexosaminyl-glucuronic acid, was demonstrated. This is the first complete and detailed secondary structure to be established for hyaluronate in any solvent. Hyaluronate is compared with chondroitin sulphate, dermatan sulphate, heparan sulphate and keratan sulphate in their potential to form secondary structures with features in common. The significance of the details of the structure to its overall stability, and the probability of their persistence into aqueous environments, are discussed. The presence of all or most of the secondary structure in glycosaminoglycuronans is correlated with a space-filling function in the tissue, and with a high carbohydrate content in the parent proteoglycan in the case of the chondroitin sulphates.

Carbon-13 and nitrogen-14 NMR spectra of 1-(substituted phenyl)pyridinium salts

1980 ◽  
Vol 45 (10) ◽  
pp. 2766-2771 ◽  
Author(s):  
Antonín Lyčka
Keyword(s):  
Heavy Water ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Pyridinium Salts ◽  
Nmr Signals ◽  
C Nmr

The 13C and 14N NMR spectra of 1M solutions of 1-(substituted phenyl)pyridinium salts (4-CH3, 4-OCH3, H, 4-Cl, 4-Br, 4-I, 3-NO2, 4-NO2, 2,4-(NO2)2 (the 13C NMR only)) have been measured in heavy water at 30 °C. The 13C and 14N chemical shifts, the 1J(CH) coupling constants, some 3J(CH) coupling constants, and values of half-widths Δ 1/2 of the 14N NMR signals are given. The 13C chemical shifts of C(4) correlate with the σ0 constants (δC(4) = (1.79 ± 0.097) σ0 + (147.67 ± 0.041)), whereas no correlation of the nitrogen chemical shifts with the σ constants has been found. The half-widths Δ 1/2 correlate with the σ0 constants (Δ 1/2 = (76.2 ± 4.9) σ0 + (106.4 ± 2.2)) except for 1-phenylpyridinium chloride.

Gradient-Enhanced Inverse-Detected NMR Techniquesfor Determination of 1H-15N Coupling Constants in 2,2-Dimethylpenta-3,4-dienal Derivatives

1997 ◽  
Vol 62 (11) ◽  
pp. 1747-1753 ◽  
Author(s):  
Radek Marek
Keyword(s):  
Double Bond ◽  
Chemical Shifts ◽  
Multiple Bond ◽  
Coupling Constants ◽  
Single Quantum ◽  
Nmr Techniques ◽  
Phase Sensitive ◽  
Heteronuclear Coupling

Determination of 15N chemical shifts and heteronuclear coupling constants of substituted 2,2-dimethylpenta-3,4-dienal hydrazones is presented. The chemical shifts were determined by gradient-enhanced inverse-detected NMR techniques and 1H-15N coupling constants were extracted from phase-sensitive gradient-enhanced single-quantum multiple bond correlation experiments. Stereospecific behaviour of the coupling constants 2J(1H,15N) and 1J(1H,13C) has been used to determine the configuration on a C=N double bond. The above-mentioned compounds exist predominantly as E isomers in deuteriochloroform.

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