13C NMR study of hydrolyzed poly(acrylonitrile)

1984 ◽  
Vol 49 (2) ◽  
pp. 506-512 ◽  
Author(s):  
Jan Loevy ◽  
Václav Janout ◽  
Hana Hrudková
Keyword(s):  
Nitric Acid ◽  
Nmr Spectroscopy ◽  
13C Nmr ◽  
Nitrile Group ◽  
Nmr Study ◽  
Acid Catalyzed ◽  
Hydrolysis Of ◽  
Poly Acrylonitrile ◽  
C Nmr

A method for the determination of chain microstructure of hydrolyzed poly(acrylonitrile) (PAN) and of copolymers of acrylonitrile with acrylamide by means of 13C NMR spectroscopy is described. Besides the overall composition of poly(acrylonitrile-co-acrylamide), this method permits the population of all acrylamide-centered compositional triads to be determined; it is then possible to follow the values of the rate constants of nitrile group hydrolysis in dependence on its neighbours. Under certain circumstances the knowledge of the mentioned triads permits also the copolymerization parameters for copolymerization of acrylonitrile with acrylamide to be determined. It was confirmed that acid-catalyzed hydrolysis of PAN in concentrated nitric acid yields acrylonitrile-acrylamide block copolymers.

Notizen: Einfache Bestimmung der Substituentenposition im Pyrrolring von Pyrrolo[2,3-d] Pyrimidinen und 7-Desazapurinnucleosiden durch 13C-NMR / Simple Determination of the Position of Substitution in the Pyrrol Ring of Pyrrolo[2,3-d]pyrimidines and 7-Deazanucleosides Using 13C NMR

1977 ◽  
Vol 32 (8) ◽  
pp. 958-960 ◽  
Author(s):  
Uwe Lüpke ◽  
Frank Seela
Keyword(s):  
Nmr Spectroscopy ◽  
13C Nmr ◽  
Side Chains ◽  
C Nmr

The position of substituents at C-5 or C-6 of pyrrolo[2,3-d]pyrimidines can be determined by 13C NMR spectroscopy. The method can also be used for 7-deazanucleosides and allows the assignment of the position of side chains.

Identification and quantitative determination of carbohydrate molecules in Greek honey by employing 13C NMR spectroscopy

2015 ◽  
Vol 7 (14) ◽  
pp. 5962-5972 ◽  
Author(s):  
Aristea Kazalaki ◽  
Maria Misiak ◽  
Apostolos Spyros ◽  
Photis Dais
Keyword(s):  
Nmr Spectroscopy ◽  
Quantitative Determination ◽  
13C Nmr ◽  
13C Nmr Spectroscopy ◽  
C Nmr

A methodology based on 13C NMR spectroscopy was employed to detect and quantify fourteen mono-, di- and trisaccharide molecules in authentic Greek honey samples with no prior separation.

13C NMR study of the mixture MBBA/EBBA/decane: The influence of decane on the molecular ordering in the nematic phase

1989 ◽  
Vol 54 (4) ◽  
pp. 868-877
Author(s):  
Josef Šebek ◽  
Raivo Teeaar
Keyword(s):  
Nmr Spectroscopy ◽  
High Resolution ◽  
Internal Rotation ◽  
13C Nmr ◽  
Nematic Phase ◽  
Temperature Behaviour ◽  
Nmr Study ◽  
Molecular Ordering ◽  
Conformational Order ◽  
C Nmr

Influence of various amounts of decane dissolved in the eutectic nematic mixture in methoxybenzylidenebutylaniline and ethoxybenzylidenebutylaniline (MBBA/EBBA) on the ordering and structure of mesomorphic molecules has been determined employing high-resolution proton enhanced 13C NMR spectroscopy. The obtained results are compared with temperature behaviour of the ordering and structure of EBBA studied by means of the same technique. Slight differences in the ordering of the phenyl parts of molecules in the dependence on temperature and on decane concentration have been observed. This contrasts with great differences observed in the behaviour of the butyl parts of mesogenic molecules. Two possible explanation of the behaviour of butyl chain atoms in the dependence on decane concentration are presented. According to one approach, conformational order parameters of the first butyl carbons increase with the increasing decane concentration. Another possibility is that decane increases the correlation between the whole molecule rotation and the internal rotation around the first butyl bond.

scholarly journals Determination of C-23 Configuration in (20R)-23-Hydroxycholestane Side Chain of Steroid Compounds by 1H and 13C NMR Spectroscopy

2013 ◽  
Vol 8 (9) ◽  
pp. 1934578X1300800 ◽  
Author(s):  
Alla A. Kicha ◽  
Anatoly I. Kalinovsky ◽  
Alexander S. Antonov ◽  
Oleg S. Radchenko ◽  
Natalia V. Ivanchina ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
13C Nmr ◽  
13C Nmr Spectroscopy ◽  
Side Chain ◽  
Side Chains ◽  
Model Compounds ◽  
1H And 13C Nmr ◽  
C 23 ◽  
C Nmr

Epimeric (20 R,23 R)- and (20 R,23 S)-23-hydroxycholestane steroids were synthesized. Their structures were elucidated by extensive 1H and 13C NMR spectroscopy and application of the Mosher's method. All proton and carbon signals of the side chains were assigned. Based on these assignments spectral data allow the determination of the C-23 stereochemistry of (20 R)-23-hydroxycholestane side chains of the new natural steroids by comparison with spectra of the obtained model compounds. As a result, the C-23 configuration of two steroid compounds from the starfishes Lethasterias nanimensis chelifera and Lethasterias fusca was established.

scholarly journals HYDROLYSIS OF HYDROXYETHYL METHYLCELLULOSE WITH PERCHLORIC ACID AND DETERMINATION OF CHEMICAL STRUCTURE VIA 13C NMR SPECTROSCOPY

2020 ◽  
Vol 54 (5-6) ◽  
pp. 439-450
Author(s):  
SERGEY G. KOSTRYUKOV ◽  
◽  
PAVEL S. PETROV ◽  
VALENTIN A. KALYAZIN ◽  
WAJAHAT ULLAH ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
13C Nmr ◽  
Perchloric Acid ◽  
Chemical Structure ◽  
13C Nmr Spectroscopy ◽  
Hydrolysis Of

1H and 13C NMR study of (X-phenyl)-5-nitro-2-furylvinyl ethers

1980 ◽  
Vol 45 (12) ◽  
pp. 3557-3563 ◽  
Author(s):  
Miloslava Dandárová ◽  
Jaroslav Kováč ◽  
Daniel Végh
Keyword(s):  
Nmr Spectroscopy ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Furan Ring ◽  
Chemical Shifts ◽  
1H And 13C Nmr ◽  
H Nmr ◽  
Nmr Study ◽  
Hammett Σ Constants ◽  
C Nmr

Reaction of 5-nitro-2-furylvinyltrimethylammonium bromide with substituted phenolates gave (E)- and (Z)-(X-phenyl)-5-nitro-2-furylvinyl ethers. The preffered s-cis and s-trans orientations of the furan ring in Z and E isomers, respectively, were determined by 1H NMR spectroscopy. To study the extent of p-π conjugation, 13C NMR spectra of compounds under investigation have also been measured and interpreted. Chemical shifts for ethylenic carbons and protons were correlated with Hammett σ constants.

scholarly journals A straightforward implementation of in situ solution electrochemical 13C NMR spectroscopy for studying reactions on commercial electrocatalysts: ethanol oxidation

2015 ◽  
Vol 51 (38) ◽  
pp. 8086-8088 ◽  
Author(s):  
L. Huang ◽  
E. G. Sorte ◽  
S.-G. Sun ◽  
Y. Y. J. Tong
Keyword(s):  
Nmr Spectroscopy ◽  
13C Nmr ◽  
Ethanol Oxidation ◽  
13C Nmr Spectroscopy ◽  
Nmr Study ◽  
C Nmr

The first in situ solution electrochemical 13C NMR study of ethanol oxidation on commercial Pt/C and PtRu/C was reported.

13C NMR study of tetrosides and their derivatives

1980 ◽  
Vol 45 (10) ◽  
pp. 2779-2783 ◽  
Author(s):  
Jiří Urban ◽  
Miroslav Marek ◽  
Jiří Jarý ◽  
Petr Sedmera
Keyword(s):  
13C Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Direct Coupling ◽  
Coupling Constants ◽  
Anomeric Configuration ◽  
Nmr Study ◽  
C Nmr

13C NMR spectra of 23 tetrose derivatives were assigned. The C(1) resonates below 103 ppm with compounds having cis-arranged substituents at C(1) and C(2) and above 106 ppm with compounds having trans-arrangement. The carbon-13 chemical shifts are mainly influenced by the 1,2-interaction. The magnitudes of direct coupling constants 1J(C(1), H) cannot be used for the determination of the anomeric configuration.

Benzyl ethers of methyl α-D-glucopyranoside

1980 ◽  
Vol 45 (7) ◽  
pp. 1959-1963 ◽  
Author(s):  
Dušan Joniak ◽  
Božena Košíková ◽  
Ludmila Kosáková
Keyword(s):  
Kinetic Study ◽  
Spectrophotometric Determination ◽  
Reductive Cleavage ◽  
Ether Bond ◽  
Benzyl Ethers ◽  
Acid Catalyzed ◽  
Model Substances ◽  
Hydrolysis Of

Methyl 4-O-(3-methoxy-4-hydroxybenzyl) and methyl 4-O-(3,5-dimethoxy-4-hydroxybenzyl)-α-D-glucopyranoside and their 6-O-isomers were prepared as model substances for the ether lignin-saccharide bond by reductive cleavage of corresponding 4,6-O-benzylidene derivatives. Kinetic study of acid-catalyzed hydrolysis of the compounds prepared was carried out by spectrophotometric determination of the benzyl alcoholic groups set free, after their reaction with quinonemonochloroimide, and it showed the low stability of the p-hydroxybenzyl ether bond.

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