Amino-acid zwitterion equilibria: vibrational and nuclear magnetic resonance studies of methyl-substituted thiazolidine-4-carboxylic acids

1986 ◽  
Vol 64 (6) ◽  
pp. 1215-1219 ◽  
Author(s):  
H. E. Howard-Lock ◽  
C. J. L. Lock ◽  
M. L. Martins ◽  
P. S. Smalley ◽  
R. A. Bell
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Amino Acid ◽  
Magnetic Resonance ◽  
Infrared Spectra ◽  
Nmr Spectra ◽  
Infrared And Raman Spectra ◽  
Solid Samples ◽  
Magnetic Resonance Studies ◽  
Cysteine Hydrochloride ◽  
C Nmr

Infrared and Raman spectra (4000–100 cm−1) of solid samples of six different methyl substituted thiazolidine products of D-penicillamine and L-cysteine hydrochloride have been observed and assigned. Infrared spectra in D2O solutions have been obtained for comparison in order to study the amino-acid zwitterion equilibria. Proton and 13C nmr spectra for the compounds have also been measured.

13C nuclear magnetic resonance studies. 58. 13C spectra of a variety of bicyclo[2.2.2]octane derivatives. Further definition of the deshielding δ effect

1976 ◽  
Vol 54 (6) ◽  
pp. 917-925 ◽  
Author(s):  
J. B. Stothers ◽  
C. T. Tan
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nmr Spectra ◽  
Magnetic Resonance Studies ◽  
13C Nuclear Magnetic Resonance ◽  
Definition Of ◽  
C Nmr ◽  
Nuclear Magnetic

The 13C nmr spectra of 35 bicyclo[2.2.2]octane and -octene derivatives have been determined to extend our examinations of the effects of stereochemistry on the shieldings of closely neighboring carbons. This series includes a variety of methyl substituted bicyclooctanols and -octenols as well as the corresponding hydrocarbons and some bicyclooctanones. With the bicyclo[2.2.2]octane skeleton it is possible to examine an array of systems having substituents separated by three and four bonds in a variety of orientations. The interactions, termed γ and δ effects, respectively, produce distinctive shielding variations which are useful for stereochemical elucidations. Particularly interesting are the pronounced shifts observed for the carbons bearing closely neighboring substituents. Characteristically, for vicinal substituents, these carbons are shielded while for syn-axial δ interactions, these carbons are deshielded by as much as 8.6 ppm. The results are compared with the trends found in other sterically crowded Systems.

13C nuclear magnetic resonance studies. 55. A comparison of the stereochemical dependence of γ- and δ-substituent effects on 13C shieldings in several norbornanols and norbornenols

1976 ◽  
Vol 54 (8) ◽  
pp. 1211-1221 ◽  
Author(s):  
J. B. Stothers ◽  
C. T. Tan ◽  
K. C. Teo
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nmr Spectra ◽  
Substituent Effects ◽  
Magnetic Resonance Studies ◽  
Considerable Potential ◽  
13C Nuclear Magnetic Resonance ◽  
Insight Into ◽  
C Nmr ◽  
Nuclear Magnetic

The 13C nmr spectra of a series of 50 methyl substituted norbornanols have been determined to gain further insight into the nature of stereochemical effects on the shieldings of carbons having closely neighboring substituents. The relatively rigid norbornyl skeleton permits examination of a variety of orientations of substituents separated by three and four bonds, the γ and δ interactions, respectively. While methyl carbons close to γ substituents exhibit upfield shifts, as is well established, methyl carbons close to δ substituents are significantly deshielded. Even more striking shifts are found for the carbons bearing these closely lying groups. The penultimate carbons in a fragment having a δ interaction between terminal groups show deviations of up to +11 ppm from the shieldings predicted by simple additivity. For fragments having a corresponding γ interaction, the penultimate carbons absorb as much as −10 ppm from the values expected by additivity. These deviations have considerable potential for stereochemical assignments and offer a challenge for theoretical interpretation.Some norbornenols and the acetates of several of the norbornanols were also included in this series and the latter shieldings are compared briefly with those observed for the parent alcohols.

scholarly journals 13C nuclear magnetic resonance studies. 64. The 13C spectra of a variety of bicyclo[3.2.1]octanols

1977 ◽  
Vol 55 (5) ◽  
pp. 841-848 ◽  
Author(s):  
J. B. Stothers ◽  
C. T. Tan
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nmr Spectra ◽  
Substituent Effects ◽  
Ring System ◽  
Hydroxyl Group ◽  
Magnetic Resonance Studies ◽  
13C Nuclear Magnetic Resonance ◽  
C Nmr ◽  
Shielding Effects

The 13C nmr spectra of a series of 20 bicyclo[3.2.1]octanols and -octenols have been determined to examine the shielding effects of the hydroxyl group on the skeletal carbons in this ring system. For comparison, the previously unreported data for a few closely related alcohols in the [2.1.1], [2.2.1], and [3.2.2] systems were also collected. The utility of these substituent effects for configuraional and conformational assignments is discussed.

Nuclear Magnetic Resonance Studies on Aromatic Compounds, IV 13C NMR Spectra of Some Disulpho-substituted 1- and 2-Naphthols

1977 ◽  
Vol 32 (7) ◽  
pp. 818-820 ◽  
Author(s):  
Kauko Räisänen ◽  
Lauri H. J. Lajunen
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Aromatic Compounds ◽  
Nmr Spectra ◽  
Hydroxyl Group ◽  
Mesomeric Effect ◽  
13C Nmr Spectra ◽  
Magnetic Resonance Studies ◽  
Fine Splitting ◽  
Substituted 1 ◽  
C Nmr

The 13C NMR spectra of 1-hydroxynaphthalene-3,6-disulphonic, 1-hydroxynaphthalene- 3,8-disulphonic, 2-hydroxynaphthalene-3,6-disulphonic, and 2-hydroxynaphthalene-6,8-disulphonic acids were determined with and without noise-decoupling. The fine splitting caused by the long-range couplings pattern was used in the identification of the resonances lines of the 13C nuclei. The combined influence of the mesomeric effect of the hydroxyl group and that of the sulphonate groups have been discussed.

Determination and Identification of Chondroitin Sulfate from Tilapia Byproducts

2013 ◽  
Vol 690-693 ◽  
pp. 1318-1321 ◽  
Author(s):  
Zhen Hua Duan ◽  
Chang Yu Cheng ◽  
Yang Hai ◽  
Ju Lan Wang
Keyword(s):  
Nuclear Magnetic Resonance ◽  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Magnetic Resonance ◽  
Chondroitin Sulfate ◽  
Infrared Spectra ◽  
Oreochromis Niloticus ◽  
High Performance ◽  
Nmr Spectra ◽  
Ir And Nmr Spectra

In order to probe the structure of chondroitin sulfate (CS) from tilapia fish, the CS was extracted from tilapia (Oreochromis niloticus) byproducts with the combination of ultrasonic and microwave, some means including high performance liquid chromatography (HPLC), infrared spectra (IR) and nuclear magnetic resonance (NMR) were used in this paper. The data of HPLC exhibited that the obtained chondroitin sulfate is of highly purity (98.78%). IR and NMR spectra indicated that the sample consisted of both chondroitin-4-sulfate and chondroitin-6-sulfate, and the proportion of chondroitin-6-sulfate was higher than chondroitin-4-sulfate.

Amino acid/zwitterion equilibria II: vibrational and NMR studies of substituted thiazolidine-4-carboxylic acids

1991 ◽  
Vol 69 (11) ◽  
pp. 1721-1727 ◽  
Author(s):  
H. E. Howard-Lock ◽  
C. J. L. Lock ◽  
M. L. Martins
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Amino Acid ◽  
Carboxylic Acids ◽  
Infrared And Raman Spectra ◽  
Solid Samples ◽  
Nmr Studies ◽  
Nuclear Magnetic Resonance Spectra ◽  
Key Words Amino Acid ◽  
Methyl Derivatives ◽  
Derivatives Of

Infrared and Raman spectra (4000–100 cm) of solid samples of seven different 2-phenyl-, N-benzoyl-, and 2-ethyl-2 methyl derivatives of L-cysteine and D-penicillamine have been observed and assigned. Proton and 13C nuclear magnetic resonance spectra for the compounds have also been measured. Amino acid/zwitterion equilibria are discussed with reference to pK values and the vibrational spectra. Key words: amino acid/zwitterion equilibria, thiazolidine carboxylic acids.

scholarly journals Applications D'Intelligence Artificielle Dans La Chimie Organique. XVII. Nouveaux Programmes Du Projet SISTEMAT

1994 ◽  
Vol 12 (2) ◽  
pp. 91-98 ◽  
Author(s):  
Vincente de Paulo Emerenciano ◽  
Gilberto do V. Rodrigues ◽  
Patricia A. T. Macari ◽  
Sandra A. Vesti ◽  
Joao H. G. Borges ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Natural Products ◽  
Magnetic Resonance ◽  
Data Base ◽  
Mass Spectroscopy ◽  
Nmr Spectra ◽  
Heuristic Rules ◽  
Structure Generation ◽  
Natural Products Chemistry ◽  
C Nmr

This work describes the new improvements of the SISlEMAT project, one system for structural elucidation mainly in the field of Natural Products Chemistry. Some examples of the resolution of problems using13C Nuclear Magnetic Resonance and Mass Spectroscopy are given. Programs to discover new heuristic rules for structure generation are discussed. The data base contains about 100013C NMR spectra.

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