scholarly journals The unexpected roles of σ and π orbitals in electron donor and acceptor group effects on the 13C NMR chemical shifts in substituted benzenes

2017 ◽  
Vol 8 (9) ◽  
pp. 6570-6576 ◽  
Author(s):  
Renan V. Viesser ◽  
Lucas C. Ducati ◽  
Cláudio F. Tormena ◽  
Jochen Autschbach
Keyword(s):  
Electron Donor ◽  
13C Nmr ◽  
Chemical Shifts ◽  
Substituted Benzenes ◽  
Nmr Chemical Shifts ◽  
Acceptor Group ◽  
Donor And Acceptor ◽  
Electron Donor And Acceptor ◽  
C Nmr ◽  
Group Effects

NH2 and NO2 group effects on 13C NMR chemical shifts in substituted benzenes are explained by σ- instead of π-orbitals.

The halogen effect on the 13C NMR chemical shift in substituted benzenes

2018 ◽  
Vol 20 (16) ◽  
pp. 11247-11259 ◽  
Author(s):  
Renan V. Viesser ◽  
Lucas C. Ducati ◽  
Cláudio F. Tormena ◽  
Jochen Autschbach
Keyword(s):  
Chemical Shift ◽  
13C Nmr ◽  
Chemical Shifts ◽  
Nmr Chemical Shift ◽  
Substituted Benzenes ◽  
Nmr Chemical Shifts ◽  
Halogen Effect ◽  
C Nmr ◽  
Group Effects

X (F, Cl, Br, I) and R (NH2, NO2) group effects on 13C NMR chemical shifts are explained by π and σ orbitals, respectively.

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.

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.

The determination of the stereochemistry of epoxides located at the 5,6-positions of decalinic systems: An empirical method based on 13C NMR chemical shifts

2002 ◽  
Vol 80 (7) ◽  
pp. 774-778 ◽  
Author(s):  
Raquel M Cravero ◽  
Guillermo R Labadie ◽  
Manuel González Sierra
Keyword(s):  
13C Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Empirical Method ◽  
Nmr Chemical Shifts ◽  
13C Nmr Chemical Shifts ◽  
Empirical Rule ◽  
C Nmr

The 13C NMR spectra of a series of 5,6-epoxides in decalinic systems were studied. The interpretation of the chemical shifts allowed us to formulate an empirical rule to predict the epoxide stereochemistry. A discussion of the scope and limitations of this method and its extension to larger carbon skeletons is also presented.Key words: epoxide stereochemistry, 13C NMR, NMR, decalinic systems, oxiranes.

Interpretation of 13C NMR chemical shifts of Hantzsch's pyridines and 1,4-dihydropyridines

1984 ◽  
Vol 49 (10) ◽  
pp. 2393-2399 ◽  
Author(s):  
Antonín Kurfürst ◽  
Petr Trška ◽  
Igor Goljer
Keyword(s):  
13C Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Correlation Equations ◽  
Pyridine Derivatives ◽  
Nmr Chemical Shifts ◽  
13C Nmr Chemical Shifts ◽  
C Nmr

1H and 13C NMR spectra of twelve 1,4-dihydropyridines I and twelve corresponding pyridine derivatives II have been measured in hexadeuteriodimethyl sulphoxide and interpreted. Correlation equations are given for the chemical shifts of the atoms in the heterocyclic rings of the two series of compounds.

Increments for 1H and 13C NMR chemical shifts in pinacol arylboronates

2012 ◽  
Vol 90 (1) ◽  
pp. 71-74
Author(s):  
Di Qiu ◽  
Zhitong Zheng ◽  
Fanyang Mo ◽  
Yan Zhang ◽  
Jianbo Wang
Keyword(s):  
Benzene Ring ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
1H And 13C Nmr ◽  
Nmr Chemical Shifts ◽  
Cross Coupling Reactions ◽  
C Nmr

Arylboronates are important compounds widely used in cross-coupling reactions. By analyzing the NMR spectra data of a variety of pinacol arylboronates, we have determined the increments for 1H and 13C NMR chemical shifts caused by a pinacol boronate substituent in the benzene ring. These data can be used in the estimation of chemical shifts of aromatic pinacol boronates.

Studies on Poplar Veneer Dyeing with Reactive Yellow Dyes

2014 ◽  
Vol 1049-1050 ◽  
pp. 118-122
Author(s):  
Sheng Fei Yu ◽  
Yuan Liu ◽  
Xian Jun Li ◽  
Wu Sheng Luo
Keyword(s):  
Electron Donor ◽  
Spectrophotometric Method ◽  
Steric Hindrance ◽  
Characteristic Parameters ◽  
Fixation Rate ◽  
Acceptor Group ◽  
Donor And Acceptor ◽  
Electron Donor And Acceptor ◽  
The Relationship

In this paper, the relationship is studied by spectrophotometric method between the structure of reactive yellow X-R, reactive yellow K-6G, reactive yellow KN-GR, reactive yellow M-5G, reactive yellow M-3RE, reactive yellow EF-3R and their colors, poplar veneer dyeing characteristic parameters S, E, R, F values, exhaustion curves and fixation curves. The results showed that longer conjugated system and better coordination of electron donor and acceptor group and smaller steric hindrance generates longer absorbance wavelength. The S value of six active dyes is reactive yellow X-R> reactive yellow KN-GR> reactive yellow K-6G> reactive yellow M-5G> reactive yellow M-3RE> reactive yellow EF-3R, the R and E and F value is reactive yellow M-3RE> reactive yellow M-5G> reactive yellow EF-3R> reactive yellow X-R> reactive yellow KN-GR> reactive yellow K-6G. The exhaustion and fixation rate is increasing with the increasing of time, except that the exhaustion containing single chlorine-triazine is decreasing within 10min after addition of alkali.

13C-Kernresonanzspektroskopische Untersuchungen an Carbonyl-, Phosphonyl- und Sulfonyl-Verbindungen mit Methylen-Brücken / 13C NMR Spectroscopic Investigations of Methylene-bridged Carbonyl, Phosphonyl and Sulfonyl Compounds

1976 ◽  
Vol 31 (2) ◽  
pp. 153-157 ◽  
Author(s):  
Wolfgang Althoff ◽  
Manfred Fild ◽  
Hans-Peter Rieck
Keyword(s):  
13C Nmr ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Nmr Chemical Shifts ◽  
Spectroscopic Investigations ◽  
C Nmr

Compounds of the type R1-CH2-R2, where R1 and R2 represent phosphonyl, carbonyl and sulfonyl groups have been investigated by 13C NMR. Chemical shifts and coupling constants of carbon to phosphorus or fluorine are discussed.

Notizen: 13C NMR Spectroscopic Study of Pentacarbonylacetonitrilemetal(0) Complexes of the Group 6 B Elements

1993 ◽  
Vol 48 (10) ◽  
pp. 1431-1432 ◽  
Author(s):  
Saim Özkar ◽  
Zahide Özer
Keyword(s):  
Spectroscopic Study ◽  
13C Nmr ◽  
Chemical Shifts ◽  
Metal Carbonyl ◽  
Nmr Chemical Shifts ◽  
H Nmr ◽  
Group 6 ◽  
C Nmr

The complexes M(CO)5(CH3CN) (M: Cr, Mo, W) were obtained from the substitution of THF in M(CO)5(THF) which has been generated by photolysis of M(CO)6 in THF and characterized by using IR, 1H NMR and 13C NMR spectroscopies. The acetonitrile ligand is found to be N-bonded to the M(CO)5-moiety with a local C4v-symmetry. The effect of the acetonitrile ligand on the metal-carbonyl bonding was discussed in terms of 13C NMR chemical shifts.

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