The Lewis acid complexes of α,β-unsaturated carbonyl and nitrile compounds. A nuclear magnetic resonance study

1982 ◽  
Vol 60 (6) ◽  
pp. 801-808 ◽  
Author(s):  
Ronald F. Childs ◽  
D. Lindsay Mulholland ◽  
Alan Nixon
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Nmr Spectroscopy ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Lewis Acid ◽  
Lewis Acids ◽  
Acid Group ◽  
Nuclear Magnetic Resonance Study ◽  
Magnetic Resonance Study ◽  
C Nmr

1:1 Complexes of a range of Lewis acids with crotonaldehyde (1) have been systematically investigated by 1H and 13C nmr spectroscopy. Lewis acids employed were: BF3, BCl3, BBr3, SnCl4, TiCl4, SbCl5, AlCl3, EtAlCl2, Et2AlCl, Et3Al2Cl3, and Et3Al. Chemical shift changes in 1H nuclei remote from the Lewis acid group were found to be remarkably regular and consistent. The study has been extended to tiglaldehyde (2), pent-3-en-2-one (3), cyclohexenone (4), methyl crotonate (5), and crotonitrile (6) and the relationships between the chemical shift differences associated with complexation of these have been explored.

Synthesis and nuclear magnetic resonance study of the compounds (2-X-1,3-dithiane) (X = H, Me, SiMe3, GeMe3, SnMe3, PbMe3) and their tetracarbonyliron complexes

1978 ◽  
Vol 56 (11) ◽  
pp. 1538-1544 ◽  
Author(s):  
David J. Cane ◽  
William A. G. Graham ◽  
Liviu Vancea
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Nmr Spectroscopy ◽  
Magnetic Resonance ◽  
Energy Barrier ◽  
Nmr Spectra ◽  
Nuclear Magnetic Resonance Study ◽  
Carbonyl Groups ◽  
Magnetic Resonance Study ◽  
Ring Inversion ◽  
C Nmr

A series of (1,3-dithiane)Fe(CO)4 complexes, (2-X-1,3-dithiane)Fe(CO)4, X = H, Me, SiMe3, GeMe3, SnMe3, PbMe3, has been prepared and characterized, and both the complexes and the free ligands studied by 1H and 13C nmr spectroscopy. The energy barrier to ring inversion in (1,3-dithiane)Fe(CO)4, ΔG298†, is 14.7 ± 0.2 kcal mol−1, some 4.4 kcal mol−1 higher than in free 1,3-dithiane.13C nmr spectra showed that within the Fe(CO)4 moiety, rapid averaging of carbonyl groups occurs down to at least −80 °C.

Sesquiterpene alkaloids from Tripterygiumwilfordii (Hook): a nuclear magnetic resonance study of 1-desacetylwilfordine, 1-desacetylwilfortrine, and 2-debenzoyl-2-nicotinoylwilforine

1990 ◽  
Vol 68 (3) ◽  
pp. 371-374 ◽  
Author(s):  
Li Ya ◽  
George M. Strunz ◽  
Larry A. Calhoun
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Nmr Spectra ◽  
Nuclear Magnetic Resonance Study ◽  
Chemical Shift Assignments ◽  
Magnetic Resonance Study ◽  
Root Extracts ◽  
C Nmr ◽  
Nuclear Magnetic

1-Desacetylwilfordine, 8, 1-desacetylwilfortrine, 9, and 2-debenzoyl-2-nicotinoylwilforine, 10, have been isolated from root extracts of the Chinese medicinal and insecticidal plant Tripterygiumwilfordii. Analysis of the 1H and 13C NMR spectra of 8 and 10, with the aid of COSY, HCCOSY, and COLOC experiments, has allowed unambiguous chemical shift assignments of all protons and carbons of these alkaloids. Keywords: alkaloids, sesquiterpene, Celastraceae, Tripterygium, NMR.

Nuclear Magnetic Resonance Study of Caesium-133 in Binary Molten Trifluoroacetate Salt Mixtures

2001 ◽  
Vol 56 (3-4) ◽  
pp. 288-290 ◽  
Author(s):  
V. N. Mirny ◽  
V. V. Trachevski ◽  
T. A. Mimaya
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Chemical Shifts ◽  
Nuclear Magnetic Resonance Study ◽  
Magnetic Resonance Study ◽  
Sodium Potassium ◽  
Salt Mixtures ◽  
Nuclear Magnetic

Abstract The chemical shifts of Cs+ in binary melts of caesium trifluoroacetate with lithium, sodium, potassium or thallium trifluoroacetates have been studied as a function of composition. An influence of added foreign cations on chemical shift of caesium nuclei has been found. The nature of the intra-and intermolecular paramagnetic contributions into the shifts of 133Cs is discussed.

1H and 13C nuclear magnetic resonance study of the complexation of uranyl ion with malic acid

1982 ◽  
Vol 60 (8) ◽  
pp. 1007-1018 ◽  
Author(s):  
M. Teresa Nunes ◽  
Victor M. S. Gil ◽  
António V. Xavier
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Malic Acid ◽  
Nuclear Magnetic Resonance Study ◽  
Magnetic Resonance Study ◽  
Molar Ratios ◽  
Nmr Study ◽  
13C Nuclear Magnetic Resonance ◽  
Ph Range ◽  
C Nmr

A full pH range 1H and 13C nmr study was performed of the complexation of UO22+ with malic acid, for variable concentrations and molar ratios. Spectral evidence for the existence of at least five complexes was found, and their stoichiometry and dependence on pH were investigated. Information on the conformation of the bound ligand molecules was also obtained.

A Carbon-13 Nuclear Magnetic Resonance Study of Chlorinated and Polyol Analogs of Glucose and Related Oligomers

1975 ◽  
Vol 53 (7) ◽  
pp. 1030-1037 ◽  
Author(s):  
Pierre Colson ◽  
Keith N. Slessor ◽  
H. J. Jennings ◽  
Ian C. P. Smith
Keyword(s):  
Aqueous Solution ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Nuclear Magnetic Resonance Study ◽  
Substantial Decrease ◽  
Magnetic Resonance Study ◽  
Carbon Dissolution ◽  
Nuclear Magnetic

Complete assignments of the carbon-13 n.m.r. spectra of the following compounds in aqueous solution are presented: 6-chloro-6-deoxy-D-glucose, 6-O-methyl-D-glucose, ribitol, glucitol, 4-O-methyl-glucitol, maltose, maltitol, 6,6′-dichloro-6,6′-dideoxymaltose, 6′-chloro-6′-deoxy-maltose, isomaltose, isomaltitol, and 6′-chloro-6′-deoxyisomaltose. Some earlier assignments for maltose are reversed. Chlorination on the exocyclic carbon of the glucopyranose ring usually results in a substantial decrease in the chemical shift of the substituted carbon (−17 p.p.m.) and the next-nearest carbon (−1.2 p.p.m.); methylation leads to an increased chemical shift for the contiguous carbon (+10 p.p.m.) and only small changes for other carbons in the molecule. The response to 4-O-methylation in glucitol is opposite for C-3 (+0.7 p.p.m.) and C-5 (−0.8 p.p.m.) demonstrating that response of a particular carbon to substitution at a neighboring carbon depends upon the configuration of the particular carbon. Dissolution of these compounds in pyridine results in a bunching together of resonances which makes unambiguous assignments very difficult. The data for this series of compounds are useful in assigning the more complex spectra of microbial polysaccharides.

A Nuclear Magnetic Resonance Study of some 4-X-Substituted-2,6-Dinitroanisoles and Related Meisenheimer 1,3- and 1,1-Complexes

1972 ◽  
Vol 50 (21) ◽  
pp. 3558-3565 ◽  
Author(s):  
M. P. Simonnin ◽  
M. J. Lecourt ◽  
F. Terrier ◽  
C. A. Dearing
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Linear Relationship ◽  
Negative Charge ◽  
Inductive Effect ◽  
Chemical Shifts ◽  
Nuclear Magnetic Resonance Study ◽  
Magnetic Resonance Study ◽  
Methoxide Ion

The structures of transient 1,3-complexes 2 and stable 1,1-complexes 3 formed by the reaction of methoxide ion with various 4-X-2,6-dinitroanisoles in DMSO-d6 are confirmed by n.m.r. spectroscopy. 13C satellites in the proton spectra of anisoles and 1,1-complexes have been used to obtain [Formula: see text] as well as 4JH–H in these symmetrical compounds.The chemical shifts of the ring protons in 1,3- and 1,1-complexes give some information concerning the influence of the substituent X on the delocalization of the negative charge. In anisoles and 1,1-complexes, [Formula: see text] of the ring protons are mainly dependent on the inductive effect of X. Furthermore, a linear relationship is observed in anisoles between the chemical shift as well as [Formula: see text] of the methoxyl protons and the Hammett σP constant of X, thus suggesting an identical geometry of these molecules at C-2,-1, and -6.

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