17O NMR Spectra of Acylated Ureas and Thioureas

1992 ◽  
Vol 57 (6) ◽  
pp. 1278-1281 ◽  
Author(s):  
Josef Jirman ◽  
Pavel Pech
Keyword(s):  
Chemical Shift ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Electronic Effects ◽  
17O Nmr ◽  
Nmr Chemical Shifts

17O NMR spectra of ten acyl- and diacylureas (I-V) and thioureas (VII-X) were measured. 17O NMR chemical shifts of the ureido oxygen in the ureas range from 240 to 310 ppm, those of the acyl oxygens from 377 to 400 ppm (acetyl groups) and 359 to 389 ppm (benzoyl groups), the half-widths being tens to hundreds Hz. Acylation of urea to the diacyl stage has an almost twice as large effect on the chemical shift of the ureido oxygen than has the monoacylation. From the viewpoint of 17O NMR shifts, no significant differences has been found in the influence of ureido and thioureido groups on the transfer of electronic effects in 1,3-diacylureas and 1,3-diacylthioureas.

17O NMR and15N NMR chemical shifts of sterically-hindered amides: ground-state destabilization in amide electrophilicity

2019 ◽  
Vol 55 (30) ◽  
pp. 4423-4426 ◽  
Author(s):  
Vittorio Pace ◽  
Wolfgang Holzer ◽  
Laura Ielo ◽  
Shicheng Shi ◽  
Guangrong Meng ◽  
...  
Keyword(s):  
Ground State ◽  
Spectroscopic Data ◽  
Chemical Shifts ◽  
Amide Bond ◽  
Electronic Effects ◽  
17O Nmr ◽  
Nmr Chemical Shifts ◽  
Combined Use ◽  
Sterically Hindered

We report17O NMR and15N NMR spectroscopic data for sterically-hindered acyclic amides. The data demonstrate that a combined use of17O NMR and15N NMR serves as a powerful tool in assessing electronic effects of the amide bond.

The ortho effect in ortho-substituted 2-(X-benzal)-1,3-indanediones, 3-(2-X-benzal)phthalides and 3-(2-X-benzal)-5,6-dihydro-4,7-dithiaphthalides: A 1H-NMR study

1980 ◽  
Vol 45 (5) ◽  
pp. 1589-1594 ◽  
Author(s):  
Ľudovít Krasnec ◽  
Eva Solčániová ◽  
Pavol Hrnčiar
Keyword(s):  
Chemical Shift ◽  
Field Effect ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Methine Proton ◽  
Electronic Effects ◽  
H Nmr ◽  
Nmr Study ◽  
Considerable Distortion ◽  
The Common

The 1H-NMR spectra of ortho-substituted 2-(X-benzal)-1,3-indanediones, 3-(2-X-benzal)-phthalides and 3-(2-X-benzal)-5,6-dihydro-4,7-dithiaphthalides have been studied. The chemical shifts observed for the methine proton were correlated with various constants of the substituents. In addition to simple correlations, two- and three-parameter correlations were also made. Statistically most important one-parameter correlations were observed for σp-constants. Apart from the common electronic effects, in the transfer of effects of the substituents from the ortho-position upon the chemical shift of the methine proton the field effect plays also an important role. The deviations observed in the case of substances substituted in both ortho-positions confirm the assumed considerable distortion of the coplanarity of the studied systems.

Electronic effects on13C NMR chemical shifts of substituted 1,3,4-thiadiazolium salts

2001 ◽  
Vol 39 (4) ◽  
pp. 182-186 ◽  
Author(s):  
Ana Cristina Souza dos Santos ◽  
Aurea Echevarria
Keyword(s):  
Chemical Shifts ◽  
Electronic Effects ◽  
Nmr Chemical Shifts

17O NMR spectra of the 1,6-anhydro-β-D-hexopyranoses and related-compounds. Determination of configurational effects on the chemical shifts

1992 ◽  
Vol 30 (4) ◽  
pp. 312-319 ◽  
Author(s):  
Jürgen Lauterwein ◽  
Jürgen Schulte ◽  
Martin Schumacher ◽  
Miloslav Černý
Keyword(s):  
Nmr Spectra ◽  
Chemical Shifts ◽  
17O Nmr ◽  
Related Compounds

17O NMR chemical shifts in polyoxometallate anions

1981 ◽  
Vol 22 (1) ◽  
pp. 129-131 ◽  
Author(s):  
R. I. Maksimovskaya ◽  
M. A. Fedotov
Keyword(s):  
Chemical Shifts ◽  
17O Nmr ◽  
Nmr Chemical Shifts

Origin of the 29Si NMR chemical shift in R3Si–X and relationship to the formation of silylium (R3Si+) ions

2020 ◽  
Vol 49 (45) ◽  
pp. 16453-16463 ◽  
Author(s):  
Winn Huynh ◽  
Matthew P. Conley
Keyword(s):  
Chemical Shift ◽  
Chemical Shifts ◽  
29Si Nmr ◽  
Surface Oxygen ◽  
Nmr Chemical Shift ◽  
Dft Methods ◽  
Nmr Chemical Shifts

The origin in deshielding of 29Si NMR chemical shifts in R3Si–X, where X = H, OMe, Cl, OTf, [CH6B11X6], toluene, and OX (OX = surface oxygen), as well as iPr3Si+ and Mes3Si+ were studied using DFT methods.

Spectroscopic Studies with N-Chloroarylsulphonamides: IR and 1H, 13C and 23Na Nmr Spectra of Sodium Salts of N-Chloro-Mono- and Di-Substituted-Benzenesulphonamides, 4-X-C6H4SO2NANCl (X = H; CH3; C2H5; F; Cl; Br; I or NO2) and i-X, j-YC6H3SO2NANCl (i-X, j-Y = 2,3-(CH3)2; 2,4-(CH3)2; 2,5-(CH3)2; 2-CH3, 4-Cl; 2-CH3, 5-Cl; 3-CH3, 4-Cl; 2,4-Cl2 or 3,4-Cl2)

2003 ◽  
Vol 58 (1) ◽  
pp. 51-56 ◽  
Author(s):  
◽  
J. D. D’Souza ◽  
B. H. Arun Kumar
Keyword(s):  
Solid State ◽  
Chemical Shift ◽  
Infrared Spectra ◽  
Phenyl Ring ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Spectroscopic Studies ◽  
Sodium Salts ◽  
Experimental Chemical Shift ◽  
23Na Nmr

In an effort to introduce N-chloroarylsulphonamides of different oxydising strengths, sixteen sodium salts of N-chloro-mono- and di-substituted benzenesulphonamides of the configuration, 4- X-C6H4SO2NaNCl (where X = H; CH3; C2H5; F; Cl; Br; I or NO2) and i-X, j-YC6H3SO2NaNCl (where i-X, j-Y = 2,3-(CH3)2; 2,4-(CH3)2; 2,5-(CH3)2; 2-CH3,4-Cl; 2-CH3,5-Cl; 3-CH3,4-Cl; 2,4- Cl2 or 3,4-Cl2) are prepared, characterized through their infrared spectra in the solid state and NMR spectra in solution. The υN-Cl frequencies vary in the range 950 - 927 cm−1. Effects of substitution in the benzene ring in terms of electron donating and electron withdrawing groups have been considered, and conclusions drawn. The chemical shifts of aromatic protons and carbon-13 in all the N-chloroarylsulphonamides have been calculated by adding substituent contributions to the shift of benzene. Considering the approximation employed the agreement between the calculated and experimental chemical shift values for different protons or carbon-13 is quite good. Effects of phenyl ring substitution on chemical shift values of both 1H and 13C are also graphically represented in terms of line diagrams.

17O NMR Chemical Shifts in Peptides

1999 ◽  
pp. 126-137 ◽  
Author(s):  
S. Kuroki ◽  
K. Yamauchi ◽  
Hiromichi Kurosu ◽  
S. Ando ◽  
Isao Ando ◽  
...  
Keyword(s):  
Chemical Shifts ◽  
17O Nmr ◽  
Nmr Chemical Shifts

scholarly journals Substituenteneinflüsse auf die 13C–NMR-chemischen Verschiebungen cis- und trans-konfigurierter Trimethincyanine / Substituent Effects on the 13C NMR Chemical Shifts of Trimethincyanines with cis and trans Configuration

1976 ◽  
Vol 31 (12) ◽  
pp. 1641-1645 ◽  
Author(s):  
Walter Grahn
Keyword(s):  
13C Nmr ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Electron Systems ◽  
Coupling Constant ◽  
Electronic Effects ◽  
Nmr Chemical Shifts ◽  
Monosubstituted Benzenes ◽  
Cis And Trans ◽  
C Nmr

The 13C NMR chemical shifts of fifteen 6 substituted 2,3-dihydro-1,4-diazepinium salts (cis trimethincyanines) (1) and twelve 2 substituted bis(dimethylamino)trimethinium salts (trans trimethincyanines) (2) have been determined. A comparison of the substituentinduced shifts (13C SCS) of 1 and 2 allows no distinction between steric and electronic effects. In the three 6 п-electron systems 1, 2 and monosubstituted benzenes the 13C SCS are similar for the substituent bearing carbon atoms. A surprisingly large 4JFCCNC coupling constant has been observed.

Phosphinsubstituierte Chelatliganden, XXIII [1] Darstellung und NMR-Spektren von Alkyl-arylphosphinothioformamiden, R(Ph)PC(S)NHMe / Phosphine-Substituted Chelate Ligands, XXIII [1] Synthesis and NMR Spectra of Alkyl-arylphosphinothioformamides, R(Ph)PC(S)NHMe

1987 ◽  
Vol 42 (1) ◽  
pp. 77-83 ◽  
Author(s):  
Udo Kunze ◽  
Rolf Tittmann
Keyword(s):  
Chemical Shift ◽  
Linear Correlation ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Cone Angle ◽  
Coupling Constants ◽  
Methyl Isothiocyanate ◽  
Signal Sets ◽  
The Asymmetry ◽  
C Nmr

Abstract A series of alkyl-arylsubstituted N-methyl phosphinothioformamides, R(Ph)PC(S)NHMe (2 a-g), with varying bulkiness of the alkyl rest was synthesized from the racemic secondary phosphines 1a-g and methyl isothiocyanate. 1H and 13C NMR spectra of 2a−g reveal signal sets of diastereotopic nuclei due to the asymmetry of the molecule. The chemical shift and coupling constants were confirmed by simulation in case of 2b, c. The vicinal 31P−13C couplings of the menthyl and neomenthyl compounds 2f, g show an "anti-Karplus" behaviour (3J(gauche) > 3J(trans)) and allow the conformational assignment of the alicyclic group. The 31P chemical shifts of 2a−d give a linear correlation with the cone angle of the alkyl substituents quoted from literature.

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