Substituent effects on the 13 C NMR chemical shifts of the imine carbon in N -(4-X-benzylidene)-4-(4-Y-styryl) anilines

2012 ◽  
Vol 25 (12) ◽  
pp. 1343-1350 ◽  
Author(s):  
Zhengjun Fang ◽  
Chenzhong Cao ◽  
Guanfan Chen
Keyword(s):  
Chemical Shifts ◽  
Substituent Effects ◽  
Nmr Chemical Shifts ◽  
C Nmr

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.

Synthetic and 1H and 13C NMRSpectral Studies on N-(Mono-substitutedphenyl)- acetamides and Substituted Acetamides, 2/3/4-YC6H4NH-COCH3–iXi (Y = CH3, F, Cl, Br, NO2; X = Cl, CH3; i = 0, 1, 2, 3)

2006 ◽  
Vol 61 (10-11) ◽  
pp. 595-599
Author(s):  
Basavalinganadoddy Thimme Gowda ◽  
Shilpa Lakshmipathy ◽  
Jayalakshmi K. Lakshmipathy
Keyword(s):  
Electron Density ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Nmr Chemical Shifts ◽  
H Nmr ◽  
C Nmr

Nineteen N-(2/3/4-methyl/halo/nitro-phenyl)-acetamides and substituted acetamides, 2/3/4- YC6H4NH-CO-CH3−iXi (Y = CH3, F, Cl, Br or NO2; X = Cl or CH3 and i = 0, 1, 2 or 3), have been prepared, characterized, and their 1H and 13C NMR spectra in solution measured and correlated. 1H and 13C NMR chemical shifts were assigned to the protons and carbon atoms, respectively, in line with those for similar compounds. Since the chemical shifts are dependent on the electron density around the nucleus or associated with the atom to which it is bound, the incremental shifts of the aromatic protons or carbon atoms due to -NH-CO-CH3−iXi and -CO-CH3−iXi (X = Cl or CH3 and i = 0, 1, 2, 3) in all the N-phenyl-substituted acetamides, C6H5NH-CO-CH3−iXi, are calculated by comparing the proton or carbon chemical shifts of these compounds with those of benzene or aniline. The incremental shifts due to the groups in the parent compounds have also been computed by comparing the chemical shifts of the protons or carbon atoms in these compounds with those of benzene or aniline, respectively. The computed incremental shifts and other data were used to calculate the 1H and 13C NMR chemical shifts of the substituted compounds in three different ways. The calculated chemical shifts by the three methods compared well with each other and with the observed chemical shifts, testing the validity of the principle of additivity of the substituent effects in these compounds. The variation of 1H NMR chemical shifts of either the aromatic or N-H protons, with the substituents in N-(phenyl)- and N-(2/3/4-chloro/methylphenyl)-acetamides and substituted acetamides did not follow the same trend, while the variation of the 13C NMR chemical shifts of C-1 and C=O carbon atoms and those of alkyl carbon atoms of these compounds followed more or less the same trend.

Chemometrical analysis of substituent effects on 13C and 15N NMR chemical shifts in 1-aroyl-3-substituted thioureas

1989 ◽  
Vol 54 (9) ◽  
pp. 2399-2407 ◽  
Author(s):  
Oldřich Pytela ◽  
Josef Jirman ◽  
Antonín Lyčka
Keyword(s):  
Latent Variables ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
The Other ◽  
15N Nmr ◽  
Nmr Chemical Shifts ◽  
Additional Constant ◽  
Substituent Constants ◽  
Derivatives Of ◽  
C Nmr

The methods of conjugated deviations and regression analysis have been used to study the substituent effects on 13C and 15N NMR chemical shifts of 12 derivatives of 1-aroyl-3-phenylthiourea and 1-aroyl-3-methylthiourea. The 13C NMR chemical shifts can be described by two latent variables, one univocally correlated with the Hammett substituent constants (r = 0.993) and the other reflecting the increased shielding of the nuclei due to overlap of the adjacent bond electrons as a consequence of electron-donor or electron-acceptor character of the substituents.This effect is less pronounced with the 15N nuclei. Application of dual substituent constants σR, σF with the additional constant σα describing the polarization has failed in giving sufficiently close correlations and explanation of the substituent effect found.

Long-range transmission of substituent effects on 13 C NMR chemical shifts of imine carbon in benzylidene anilines

2012 ◽  
Vol 26 (3) ◽  
pp. 249-255 ◽  
Author(s):  
Zhengjun Fang ◽  
Chenzhong Cao ◽  
Weihe Wu ◽  
Lu Wang
Keyword(s):  
Long Range ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Nmr Chemical Shifts ◽  
C Nmr

NMR spectra (13C and 29Si) as a probe into the electronic structure of cyclopropylsilanes

1983 ◽  
Vol 48 (12) ◽  
pp. 3396-3401 ◽  
Author(s):  
Jan Schraml ◽  
Micheline Grignon-dubois ◽  
Jacques Dunoguès ◽  
Harald Jancke ◽  
Günter Engelhardt ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Silicon Atom ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Cyclopropane Ring ◽  
Substituent Effects ◽  
Nmr Chemical Shifts ◽  
Back Bonding ◽  
C Nmr

29Si and 13C NMR chemical shifts are reported for cyclopropyl derivatives with the structure (CH3)3-nRnSiC3H5 where R = OSi(CH3)3 and OCH3. He carbon chemical shifts show substituent effects which are intermediate between those found in the corresponding vinyl and ethyl silanes. The 29Si chemical shifts, however, do not provide any evidence for back bonding between the cyclopropane ring and the silicon atom.

Synthesis, X-ray structure determination, and formation of 3,4,5-trichloroguaiacol occurring in kraft pulp spent bleach liquors

1980 ◽  
Vol 58 (8) ◽  
pp. 815-822 ◽  
Author(s):  
K. Lindström ◽  
F. Österberg
Keyword(s):  
Reaction Mechanism ◽  
Melting Point ◽  
Structure Determination ◽  
Kraft Pulp ◽  
Chemical Shifts ◽  
X Ray ◽  
Nmr Chemical Shifts ◽  
Chemical Pulp ◽  
C Nmr

3,4,5-Trichloroguaiacol, which is formed during bleaching of chemical pulp and shown to bioaccumulate in fish, has been synthesized. The structure of the compound has been determined by means of X-ray analysis. The values of the 13C nmr chemical shifts and melting point differ from those previously reported. A reaction mechanism is suggested for the formation of 3,4,5- and 4,5,6-trichloroguaiacol.

scholarly journals Substituent Effects on the Carbon-13 NMR Chemical Shifts of Cyclopropyl Carbons inp-Substituted(cis- andtrans-2-Chlorocyclopropyl)benzenes

1990 ◽  
Vol 63 (10) ◽  
pp. 2836-2842 ◽  
Author(s):  
Yoshiaki Kusuyama ◽  
Tamami Kagosaku ◽  
Takeshi Hasegawa
Keyword(s):  
Chemical Shifts ◽  
Substituent Effects ◽  
Nmr Chemical Shifts

Preparation, 1H and 13C NMR, and ab initio/IGLO study of mono-O-protonated deltic acid and theoretical investigation of di-, tri-, and tetra-O-protonated deltic acids

1999 ◽  
Vol 77 (5-6) ◽  
pp. 525-529 ◽  
Author(s):  
GK Surya Prakash ◽  
Golam Rasul ◽  
George A Olah ◽  
Ronghua Liu ◽  
Thomas T Tidwell
Keyword(s):  
Nmr Spectroscopy ◽  
Ab Initio ◽  
Theoretical Investigation ◽  
13C Nmr ◽  
Chemical Shifts ◽  
1H And 13C Nmr ◽  
Nmr Chemical Shifts ◽  
Molar Solution ◽  
Protonated Species ◽  
C Nmr

The hitherto elusive mono-O-protonated deltic acid C3O3H3+ was prepared by protolysis of di-tert-butoxy deltate in FSO3H-SO2ClF and in FSO3H:SbF5 (Magic Acid; 1:1 molar solution) in SO2ClF as solvent at -78°C and was characterized by 1H and 13C NMR spectroscopy. The structure and NMR chemical shifts were also calculated by the ab initio/IGLO method. No NMR evidence was found for persistent di-O-protonated deltic acid under these conditions, although a limited equilibrium with the mono-O-protonated species can be involved. Di-, tri-, and tetra-O-protonated deltic acids were also studied by ab initio/IGLO method.Key words: protonated deltic acid, aromaticity, superacids, NMR spectroscopy, ab initio and IGLO calculations.

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