Preparation and properties of β-ketosulphones of 5-nitrofuran series. Study of transfer of electronic effects through sulphone group

1982 ◽  
Vol 47 (2) ◽  
pp. 617-621 ◽  
Author(s):  
Dana Polakovičová ◽  
Adolf Jurášek ◽  
Vladimír Kvasnička
Keyword(s):  
Linear Dependence ◽  
Quantum Chemical ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Electronic Effects ◽  
H Nmr ◽  
Physical Measurements ◽  
Hammett Constants ◽  
Series Study ◽  
Proton Chemical Shifts

A series of 2-(5-nitro-2-furyl)-2-oxoethylarylsulphones have been synthesized by reaction of 5-nitro-2-bromoacetylfuran with sodium p-X-benzenesulphinates (where X = H, CH3, OCH3, CH3CONH, NH2, N(CH3)2, Cl, NO2) and used for a study of transfer of electronic effects of the substituent through SO2 group. The found linear dependence between the proton chemical shifts in 1H NMR spectra (and pKa values of the CH2 group) and the Hammett constants of the substituents proves the existence of the transfer through SO2 group. The results of physical measurements were compared with the data obtained by quantum-chemical calculations using the EHT method.

Antimycobacterial thiobenzanilides

1990 ◽  
Vol 55 (1) ◽  
pp. 307-316 ◽  
Author(s):  
Karel Waisser ◽  
Nestor Houngbedji ◽  
Miloš Macháček ◽  
Miroslav Sekera ◽  
Josef Urban ◽  
...  
Keyword(s):  
Silica Gel ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Antimycobacterial Activity ◽  
Uv Spectra ◽  
Mycobacterium Kansasii ◽  
Aromatic Rings ◽  
H Nmr ◽  
Hammett Constants ◽  
Thioamide Group

A group of 30 thiobenzanilides active against Mycobacterium kansasii have been synthesized and their 1H NMR and UV spectra and RM values (TLC on silica gel impregnated with methylsilicone oil) have been measured. From the correlation between the chemical shifts of the thioamide proton in the 1H NMR spectra and the Hammett constants it can be concluded that the substituents in both aromatic rings uniformly affect the electron density of the thioamide group. The antimycobacterial activity is probably connected with local molecular parameters and can be considered to be approximately additive with respect to both parts of the molecule.

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.

Quantum Chemical Calculation on 1H NMR Chemical Shifts of PMMA/PVPh Blends

2011 ◽  
Vol 301-303 ◽  
pp. 263-268 ◽  
Author(s):  
Wei Gui Fu ◽  
Li Chen ◽  
Bao Hui Li ◽  
Ping Chuan Sun
Keyword(s):  
Hydrogen Bonds ◽  
Polymer Blends ◽  
Quantum Chemical Calculation ◽  
Quantum Chemical ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Chemical Calculation ◽  
Oh Groups ◽  
H Nmr ◽  
Chain Conformations

Prediction of chemical shifts using quantum chemical calculation is helpful for assigning nuclear magnetic resonance (NMR) spectra, and very important in structure determination. In this paper, we calculated1H chemical shifts (δH) of poly (methyl methacrylate) (PMMA), poly (4-vinyl phenol) (PVPh) and their polymer blends. Density functional theory (DFT) was used to computeδH of hydroxyl groups (OH) for both PVPh homopolymer and PMMA/PVPh polymer blends. The calculated values forδH of OH groups with or without forming hydrogen bonds agreed reasonably well with the experimental values. It was found that the δH of OH groups moved downfield when they formed hydrogen bonds with both other OH groups and carbonyl groups (C=O). The simulated solid state1H NMR spectra based on the B3LYP // GIAO method yielded results for the PMMA, PVPh and PMMA/PVPh, showed excellent agreement with the experimental results. It indicates that the1H NMR spectra are influenced by the main-chain conformations and the hydrogen bond types.

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 Real-time prediction of 1H and 13C chemical shifts with DFT accuracy using a 3D graph neural network

2021 ◽  
Author(s):  
Yanfei Guan ◽  
S. V. Shree Sowndarya ◽  
Liliana C. Gallegos ◽  
Peter C. St. John ◽  
Robert S. Paton
Keyword(s):  
Neural Network ◽  
Real Time ◽  
Quantum Chemical ◽  
Organic Molecules ◽  
Chemical Shifts ◽  
13C Chemical Shifts ◽  
Time Prediction ◽  
Nmr Data ◽  
Proton Chemical Shifts

From quantum chemical and experimental NMR data, a 3D graph neural network, CASCADE, has been developed to predict carbon and proton chemical shifts. Stereoisomers and conformers of organic molecules can be correctly distinguished.

Chemical shifts of charge-transfer complexes and Buckingham equation

1990 ◽  
Vol 55 (9) ◽  
pp. 2131-2137
Author(s):  
Mahboob Mohammad ◽  
Ather Yaseen Khan ◽  
Tariq Mahmood ◽  
Ismat Fatima ◽  
Riffat Shaheen ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Nmr Spectra ◽  
Charge Transfer Complex ◽  
Chemical Shifts ◽  
Charge Transfer Complexes ◽  
Aprotic Solvents ◽  
Reaction Field ◽  
H Nmr ◽  
Spherical Cavities ◽  
Dipolar Aprotic Solvents

The 1H NMR spectra of the charge-transfer complex of 1-ethyl-4-methoxycarbonylpyridinium iodide have been recorded in various dipolar aprotic solvents. An attempt is made to interpret the chemical shifts in terms of Buckingham's reaction field equation for spherical cavities. A linear dependence has been found between the δ(2,6) values and the square of dielectric function for a spherical cavity, which confirms the validity of the Buckingham equation for this class of compounds.

Sign in / Sign up

Export Citation Format

Share Document