Effect of lanthanide shift reagents on 1H NMR spectra of aminopyridines

1979 ◽  
Vol 44 (3) ◽  
pp. 908-911 ◽  
Author(s):  
Antonín Lyčka ◽  
Dobroslav Šnobl
Keyword(s):  
Nmr Spectroscopy ◽  
1H Nmr ◽  
Electron Donor ◽  
Electron Acceptor ◽  
Nmr Spectra ◽  
Pyridine Ring ◽  
Chemical Shifts ◽  
Amino Group ◽  
H Nmr ◽  
Lanthanide Shift Reagents

The effect of Eu(dpm)3 and Pr(dpm)3 on the proton spectra of 2-amino-, 3-amino- and 4-aminopyridines has been studied by the 1H NMR spectroscopy in tetrachlomethane and deuteriochloroform at 25 °C. Relative changes of the induced chemical shifts of pyridine carrying electron-donor substituents (amino group) are the same as the values given in literature for pyridine ring with electron-acceptor substituents.

15N, 13C, and 1H NMR spectra of acylated ureas and thioureas

1987 ◽  
Vol 52 (10) ◽  
pp. 2474-2481 ◽  
Author(s):  
Josef Jirman ◽  
Antonín Lyčka
Keyword(s):  
1H Nmr ◽  
Electron Acceptor ◽  
Sulfur Atom ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
1H Nmr Spectra ◽  
Coupling Constants ◽  
Nmr Chemical Shifts ◽  
H Nmr ◽  
Better Than

A series of 1-acylated and 1,3-diacylated (acyl = acetyl or benzoyl) ureas and thioureas have been prepared and their proton-coupled and proton-decoupled 15N, 13C, and 1H NMR spectra have been measured. All the signals have been assigned. The 15N NMR chemical shifts in 1-acylated ureas and thioureas are shifted downfield as compared with δ(15N) of urea and thiourea, resp. This shift is greater for N-1 than for N-3 nitrogen atoms in both the series. When comparing acylureas and acylthioureas it is obvious from the Δδ(15N) differences that the CS group is better than CO group in transferring the electron-acceptor effect of acyl group. The proton-coupled 15N NMR spectra of the acylureas dissolved in hexadeuteriodimethyl sulphoxide exhibit a doublet of NH group and a triplet of NH2 group at 25 °C. At the same conditions the acylthioureas exhibit a doublet of NH group, the NH2 group signal being split into a doublet of doublets with different coupling constants 1J(15N, H). The greater one of these coupling constants is due to the s-trans proton with respect to the sulfur atom of the thiourea.

29Si, 13C and 1H NMR spectra of some trimethylsiloxy- and bis(trimethylsiloxy)butene isomers

1983 ◽  
Vol 48 (11) ◽  
pp. 3097-3103 ◽  
Author(s):  
Jan Schraml ◽  
Ján Šraga ◽  
Pavel Hrnčiar
Keyword(s):  
Double Bond ◽  
Nmr Spectroscopy ◽  
Oxygen Atom ◽  
1H Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
1H Nmr Spectra ◽  
Trimethylsilyl Group ◽  
H Nmr ◽  
Steric Crowding

Three isomers of trimethylsiloxybutene were prepared and identified by 1H NMR spectroscopy to be 2-trimethylsiloxy-1-butene and E and Z 2-trimethylsiloxy-2-butenes. E and Z isomers of 2,3-bis(trimethylsiloxy-2-butene were also prepared. 29Si and 13C chemical shifts in these compounds are interpreted. The shifts indicate that the spatial arrangements in the CH3-C-O-Si(CH3)3 fragment is the same in all the pertinent compounds. Steric crowding forces the trimethylsilyl group to assume conformations in which conjugation between unshared electrons of oxygen atom and the electrons of the double bond is inhibited. As a result, olefinic β carbons are deshielded and the shielding of the silicon is increased.

scholarly journals 13C and 1H NMR Spectra of Synthetic (25R)-5α-Spirostanes

1999 ◽  
Vol 23 (1) ◽  
pp. 48-49
Author(s):  
Martín A. Iglesias Arteaga ◽  
Carlos S. Pérez Martinez ◽  
Roxana Pérez Gil ◽  
Francisco Coll Manchado
Keyword(s):  
1H Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
1H Nmr Spectra ◽  
H Nmr ◽  
C 23 ◽  
Main Effects ◽  
Nmr Signals

The assignment of 13C and 1H NMR signals of synthetic (25 R)-5α-spirostanes is presented; the main effects on chemical shifts due to substitution at C-23 are briefly discussed.

scholarly journals Assessment of 1H NMR Spectroscopy for Specific Metabolite Fingerprinting of Angelica sinensis

2008 ◽  
Vol 3 (5) ◽  
pp. 1934578X0800300
Author(s):  
Dongmin Su ◽  
Jinglan Han ◽  
Shishan Yu ◽  
Hailin Qin
Keyword(s):  
Nmr Spectroscopy ◽  
1H Nmr ◽  
1H Nmr Spectroscopy ◽  
Nmr Spectra ◽  
Authentic Sample ◽  
Angelica Sinensis ◽  
Metabolite Fingerprinting ◽  
H Nmr ◽  
Pure Compounds ◽  
Polar Extracts

The 1H NMR fingerprints of fractionated non-polar extracts (CSPD A) from the roots of Angelica sinensis of six different specimens were assigned by comparison with the 1H NMR spectra of the isolated pure compounds. The 1H NMR fingerprints showed exclusively characteristic resonance signals of the major constituents of the plant. The 1H NMR fingerprint established for an authentic sample of A. sinensis can be used for authenticating A. sinensis species.

Light induced E–Z isomerization in a multi-responsive organogel: elucidation from 1H NMR spectroscopy

2015 ◽  
Vol 51 (53) ◽  
pp. 10680-10683 ◽  
Author(s):  
Sanjoy Mondal ◽  
Priyadarshi Chakraborty ◽  
Partha Bairi ◽  
Dhruba P. Chatterjee ◽  
Arun K. Nandi
Keyword(s):  
Mechanical Properties ◽  
Nmr Spectroscopy ◽  
1H Nmr ◽  
1H Nmr Spectroscopy ◽  
Nmr Spectra ◽  
H Nmr ◽  
Imine Bond

Light induced E–Z isomerization along imine bond in a multiresponsive organogel of anthracene attached 3,4,5-tris(dodecyloxy)benzohydrazide gelator altering morphology, fluorescence and mechanical properties is elucidated from 1H NMR spectra.

1H NMR Spectrum: A Team-Based Tabletop Game for Molecular Structure Elucidation

2020 ◽  
Author(s):  
Zachary Thammavongsy ◽  
Michael A. Morris ◽  
Renee Link
Keyword(s):  
Nmr Spectroscopy ◽  
1H Nmr ◽  
1H Nmr Spectroscopy ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
1H Nmr Spectra ◽  
Molecular Formula ◽  
College Level ◽  
Nmr Spectrum ◽  
Laboratory Course

The 1H NMR Spectrum game, the first example of a team-based tabletop game focused on elucidating the structures of organic small molecules using 1H NMR spectra, was developed and deployed in a college level organic chemistry lecture course and laboratory course. The tabletop game was designed as a collaborative and competitive group activity to encourage multiple rounds of play to help students reinforce their 1H NMR spectra interpretation skills. While playing in either team-based or free-for-all mode, students analyzed the provided chemical shifts, splitting patterns, integrations, and molecular formula within a designated time limit to correctly deduce the structure associated with the 1H NMR spectrum. After playing the game, students in a lecture course and a laboratory course self-reported that they felt more comfortable solving 1H NMR spectroscopy questions, found the game to be an appealing study aid, and were able to complete multiple rounds of play to strengthen their skills in interpreting 1H NMR spectra. The 1H NMR Spectrum tabletop game may serve as an engaging and competitive group learning tool to supplement teaching on 1H NMR spectroscopy.

1H NMR Spectrum: A Team-Based Tabletop Game for Molecular Structure Elucidation

2020 ◽  
Author(s):  
Zachary Thammavongsy ◽  
Michael A. Morris ◽  
Renee Link
Keyword(s):  
Nmr Spectroscopy ◽  
1H Nmr ◽  
1H Nmr Spectroscopy ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
1H Nmr Spectra ◽  
Molecular Formula ◽  
College Level ◽  
Nmr Spectrum ◽  
Laboratory Course

The 1H NMR Spectrum game, the first example of a team-based tabletop game focused on elucidating the structures of organic small molecules using 1H NMR spectra, was developed and deployed in a college level organic chemistry lecture course and laboratory course. The tabletop game was designed as a collaborative and competitive group activity to encourage multiple rounds of play to help students reinforce their 1H NMR spectra interpretation skills. While playing in either team-based or free-for-all mode, students analyzed the provided chemical shifts, splitting patterns, integrations, and molecular formula within a designated time limit to correctly deduce the structure associated with the 1H NMR spectrum. After playing the game, students in a lecture course and a laboratory course self-reported that they felt more comfortable solving 1H NMR spectroscopy questions, found the game to be an appealing study aid, and were able to complete multiple rounds of play to strengthen their skills in interpreting 1H NMR spectra. The 1H NMR Spectrum tabletop game may serve as an engaging and competitive group learning tool to supplement teaching on 1H NMR spectroscopy.

1H NMR Spectral Simplification with Achiral and Chiral Lanthanide Shift Reagents. Part II: Ethosuximide, 3-Ethyl-3-Methyl-2,5-Pyrrolidinedione, and Comparisons with Analogs

1986 ◽  
Vol 40 (4) ◽  
pp. 531-537 ◽  
Author(s):  
John Avolio ◽  
Suzanne Thomson Eberhart ◽  
Robert Rothchild ◽  
Paul Simons
Keyword(s):  
1H Nmr ◽  
Nmr Spectra ◽  
Shift Reagent ◽  
Ethyl Group ◽  
Molar Ratios ◽  
H Nmr ◽  
Lanthanide Shift Reagents ◽  
Shift Reagents

The 60 MHz 1H NMR spectra of racemic ethosuximide, 1, have been studied in detail with the achiral shift reagent, tris(6,6,7,7,8,8,8-hepta-fiuoro-2,2-dimethyl-3,5-octanedionato)europium(III), 2, and the chiral tris(3-trifluoromethylhydroxymethylene)- d-camphorato]europium(III), 3. Enantiomeric shift differences, ΔΔδ, were clearly observed for the CH3 of the ethyl group of 1 at molar ratios of 3:1 as low as 0.0385, with ΔΔδ valaues of about 12 Hz seen at a 3:1 ratio of 0.340 for CDCl3 solutions at 28°, 0.634 molal in 1. Smaller ΔΔδ values were also seen for the quaternary methyl and for one of the hydrogens at C-4. Parallel studies with 2 were performed to support assignments. Results are compared with a group of important drugs that are structurally related, including ethotoin, mephenytoin, glutethimide, methsuximide, phensuximide, and paramethadione, in terms of steric and basicity effects. Correlations of both lanthanide-induced shift (Δδ) and ΔΔδ could generally be made from simple electronic considerations related to infrared carbonyl stretching frequencies. Of the 28 sets of Δδ values assigned for the substrates, 3 gave significantly larger values than 2 in only two cases.

1H NMR Spectral Simplification with Achiral and Chiral Lanthanide Shift Reagents. Part III:* Vinclozolin

1986 ◽  
Vol 40 (6) ◽  
pp. 743-745 ◽  
Author(s):  
Alexander Hatzis ◽  
Robert Rothchild
Keyword(s):  
1H Nmr ◽  
Nmr Spectra ◽  
Optical Purity ◽  
Molar Ratio ◽  
Molar Ratios ◽  
Chiral Reagent ◽  
H Nmr ◽  
Lanthanide Induced Shifts ◽  
Lanthanide Shift Reagents ◽  
Shift Reagents

The 60 MHz 1H NMR spectra of racemic vinclozolin, 1, have been studied at 28° in CDCI3 solution with the achiral reagent tris(6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionato)europium(III), 2, and the chiral reagents tris[3-(trifluoromethylhydroxymethylene)- d-camphorato] europium(III), 3, and tris[3-(heptafluoropropylhydroxymethylene)- d-camphorato]europium(III), 4. Reagent 3 produced only small lanthanide-induced shifts and no observable enantiomeric shift differences, ΔΔδ, with 3:1 molar ratios as high as 1.40. In contrast, chiral reagent 4 produced substantial ΔΔδ for the proton, Hβ, at C-2 of the ethenyl group syn to the oxazolidinedione ring and smaller ΔΔδ for the anti proton, Hβ, at the above carbon and for the CH3. With a 4:1 molar ratio of 0.581, ΔΔδ of 7.0 Hz was seen for Hβ. A 4:1 ratio of about 0.41 should be optimum for optical purity determinations; as little as 5% of the minor enantiomer should be detectable.

Conformational study of blocked pentofuranoses and their 1,5-anhydro derivatives by 1H NMR spectroscopy

1984 ◽  
Vol 49 (1) ◽  
pp. 235-243
Author(s):  
Jaroslav Zajíček ◽  
Miloš Buděšínský ◽  
Jiří Farkaš
Keyword(s):  
Spectral Analysis ◽  
Nmr Spectroscopy ◽  
Quantum Chemical Calculations ◽  
1H Nmr ◽  
Quantum Chemical ◽  
1H Nmr Spectroscopy ◽  
Nmr Spectra ◽  
Conformational Study ◽  
H Nmr

Preferred conformations of the furanose ring and conformer population about the C(5)-C(4) bond in a series of benzoylated pentofuranosyl cyanides have been determined from their 1H NMR spectra. For the 1,5-anhydropentofuranose derivatives the results of the 1H NMR spectral analysis have been compared with the quantum chemical calculations.

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