Das JerJ-Butyl-Kation in Lösungen von Aluminiumbromid in Mono-, Di- und Tribrommethan / The terf-Butyl-Cation in Solutions of Aluminium Bromide in Mono-, Di- and Tribromomethane

1979 ◽  
Vol 34 (7) ◽  
pp. 891-895 ◽  
Author(s):  
Peter Brüggeller ◽  
Erwin Mayer
Keyword(s):  
Nmr Spectroscopy ◽  
Chemical Shift ◽  
Dilute Solutions ◽  
Concentrated Solutions ◽  
Nmr Chemical Shift ◽  
Tert Butyl ◽  
H Nmr ◽  
Saturated Solutions

Abstract The tert-butyl cation is formed from tert-BuBr in concentrated solutions of AlBr3 in CH3Br, CH2Br2 and CHBr3 and was characterized by 1H NMR spectroscopy. Stabilization of the cation depends strongly on the AlBr3 concentration: in CH3Br saturated with AlBr3, C(CH3)3+ is formed in 80% yield; in dilute solutions of AlBr3 in CH3Br the usual de-composition occurs. In saturated solutions of AlBr3 in CH2Br2 and CHBr3 the C(CH3)3+ yield is 60 and 40%, resp. The concentration of the cation decreases in all three solvents by 20 to 30% within 10 days at room temp. In concentrated solutions of AlBr3 in CH3Br the formation of the methyl-tert-butylbromonium ion as a rapidly equilibrating species is suggested. The 1H NMR chemical shift of C(CHs)3+ in the presence of AlBr3 (δ = 5.19 in CHsBr, δ = 5.23 in CH2Br2, δ = 5.35 in CHBr3) indicates strong deshielding in comparison with shifts in SbF5 and SbF5/SO2

Determination of Water Content in Bioethanol Using the 1 H NMR Chemical Shift Change

2019 ◽  
Vol 40 (4) ◽  
pp. 313-316
Author(s):  
Jeongbin Yoon ◽  
Suyeon Yun ◽  
Byungjoo Kim ◽  
Sangdoo Ahn ◽  
Kihwan Choi
Keyword(s):  
Chemical Shift ◽  
Water Content ◽  
Chemical Shift Change ◽  
Nmr Chemical Shift ◽  
H Nmr ◽  
Shift Change

scholarly journals NMR spectroscopic study of inclusion complexes of cetirizine dihydrochloride and β-cyclodextrin in solution

2007 ◽  
Vol 21 (3) ◽  
pp. 177-182 ◽  
Author(s):  
Syed Mashhood Ali ◽  
Santosh Kumar Upadhyay ◽  
Arti Maheshwari
Keyword(s):  
Aqueous Solution ◽  
Chemical Shift ◽  
Spectroscopic Study ◽  
Inclusion Complexes ◽  
Binding Constant ◽  
Spectroscopic Studies ◽  
Chemical Shift Change ◽  
Nmr Chemical Shift ◽  
H Nmr ◽  
Shift Change

Cetirizine dihydrochloride (CTZ), an antihistamine, forms two 1:1 inclusion complexes with β-cyclodextrin (β-CD) in aqueous solution as confirmed by detailed1H NMR, COSY and ROESY spectroscopic studies. The stoichiometry and overall binding constant of the complexes were determined by the treatment of1H NMR chemical shift change (Δδ) data. Most of the CTZ protons exhibited splitting in the presence of β-CD.

scholarly journals Photoisomerisierung von trans-1-(3.5-Di-tert-butyl-4-hydroxyplienyl)-2-phenyldiazen / Photoisomerization of trans-1-(3,5-Di-tert-butyl-4-hydroxyphenyl)-2-phenyldiazene

1980 ◽  
Vol 35 (2) ◽  
pp. 233-236 ◽  
Author(s):  
Edgar Hofer
Keyword(s):  
Nmr Spectroscopy ◽  
Title Compound ◽  
Tautomeric Equilibrium ◽  
Tert Butyl ◽  
H Nmr ◽  
Nmr Data ◽  
Trans Isomerization ◽  
Different Temperatures ◽  
Influence Of Solvent

AbstractLight induced isomerizations of the title compound have been studied. The thermal cis-trans isomerization 3→1 occurs via the tautomeric quinonephenylhydrazone (2) as shown by 1H NMR, spectroscopy. The influence of solvent on the thermal cis-trans isomerization is discussed. 1H NMR data of 1, 2 and 3 are given. Values of the tautomeric equilibrium 1⇋2 are determined for various solvents and different temperatures.

Chemical Shift Nonequivalence of Enantiomers of Amino Acid Derivatives in 1H NMR and 19F NMR Spectroscopy Induced by L-Chirasil- Val.

1992 ◽  
Vol 47 (7) ◽  
pp. 1034-1036 ◽  
Author(s):  
Bernhard Koppenhoefer ◽  
Michael Hummel
Keyword(s):  
Amino Acid ◽  
Nmr Spectroscopy ◽  
Chemical Shift ◽  
Methyl Esters ◽  
Enantiomeric Purity ◽  
Peak Splitting ◽  
H Nmr ◽  
Acid Methyl ◽  
Amino Acid Methyl Esters

Enantiomers of N-trifluoroacetyl-amino acid methyl esters in CC14 solution, after addition of the chiral polysiloxane (L)-Chirasil-Val, display a chemical shift nonequivalence ΔΔδ in both 1H NMR and 19F NMR spectroscopy. The effects found for the leucine and valine derivatives can be correlated with the thermodynamic parameters of interaction in the undiluted system, as determined by gas chromatography. In CDC13 solution, no peak splitting was observed. The method is potentially useful for the determination of the enantiomeric purity of substrates of low volatility.

The 1H(Se-H) NMR chemical shift in selenols and the fundamental Se-H stretching frequency

1969 ◽  
Vol 25 (6) ◽  
pp. 1160-1165 ◽  
Author(s):  
A. Merijanian ◽  
R.A. Zingaro ◽  
L.S. Sagan ◽  
K.J. Irgolic
Keyword(s):  
Chemical Shift ◽  
Nmr Chemical Shift ◽  
H Nmr
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