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.

A Novel Method for 13C-NMR Spectroscopy of Polymer in Emulsion: Quantitative Analysis of Microstructure of Crosslinked Polybutadiene in Latex

1999 ◽  
Vol 72 (5) ◽  
pp. 844-853 ◽  
Author(s):  
Seiichi Kawahara ◽  
Saori Bushimata ◽  
Takashi Sugiyama ◽  
Chihiro Hashimoto ◽  
Yasuyuki Tanaka
Keyword(s):  
Nmr Spectroscopy ◽  
High Resolution ◽  
13C Nmr ◽  
Lattice Relaxation ◽  
13C Nmr Spectroscopy ◽  
Lattice Relaxation Time ◽  
Solid Sample ◽  
Spin Lattice Relaxation ◽  
High Resolution Spectrum ◽  
C Nmr

Abstract A novel analytical method using high resolution 13C-NMR spectroscopy to study polymer latex, which is a heterogeneous system comprising polymer dispersoid and water, is described. The appropriate concentrations of surfactant and dried rubber content of a polybutadiene latex, which give the best spectrum, were found to be 1 w/v % and 10%, respectively. The half-widths of resonance peaks for the latex sample were almost identical to the half-widths obtained in solution, which were about one-third the width of those obtained using a solid sample of either a crosslinked or soluble polybutadiene. Nevertheless, the signal to noise ratio for the latex sample was slightly smaller than that for the solution sample. The values of spin-lattice relaxation time, T1, for the latex sample were similar to those for the solid sample. These demonstrate that the latex state C-NMR spectroscopy will be a powerful technique for structural characterization of crosslinked gels in the dispersoid because it gives a high resolution spectrum comparable to solution state spectroscopy, showing short T1 values corresponding to those for solid state C-NMR spectroscopy. High resolution latex state 13C-NMR spectroscopy was used to determine the concentrations of the various isomers of the polybutadiene in the dispersoid.

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 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.

13C NMR Study of Oxygen Intercalation in C60

1994 ◽  
Vol 359 ◽  
Author(s):  
P. Bernier ◽  
I. Luk'yanchuk ◽  
Z. Belahmer ◽  
M. Ribet ◽  
L. Firlej
Keyword(s):  
Charge Transfer ◽  
High Resolution ◽  
Molecular Oxygen ◽  
13C Nmr ◽  
Octahedral Site ◽  
Magnetic Characteristics ◽  
Nmr Study ◽  
Oxygen Intercalation ◽  
Fcc Structure ◽  
C Nmr

ABSTRACTHigh resolution 13C NMR has been used to investigate the properties of solid C60 after intercalation of molecular oxygen, which does not induce charge transfer with the host molecules. We show that, via the magnetic characteristics of the intercalant, information can be gained on its position and movement in the structure. In particular, molecular oxygen is found to occupy the middle of the octahedral site in the fcc structure of solid C60.

Structural study of poly(vinyl alcohol) in the gel state by high-resolution solid-state 13C NMR spectroscopy

1995 ◽  
Vol 28 (19) ◽  
pp. 6677-6679 ◽  
Author(s):  
Masatoshi Kobayashi ◽  
Isao Ando ◽  
Takahiro Ishii ◽  
Shigetoshi Amiya
Keyword(s):  
Solid State ◽  
Nmr Spectroscopy ◽  
High Resolution ◽  
Structural Study ◽  
13C Nmr ◽  
Vinyl Alcohol ◽  
13C Nmr Spectroscopy ◽  
Poly Vinyl Alcohol ◽  
Solid State 13C Nmr

scholarly journals Evidence of the Existence of 2:1 Guest–Host Complexes between Diclofenac and Cyclodextrins in D2O Solutions. A 1H and 13C NMR Study on Diclofenac/β-Cyclodextrin and Diclofenac/2-Hydroxypropyl-β-cyclodextrin Systems

1999 ◽  
Vol 23 (7) ◽  
pp. 414-415
Author(s):  
Adele Mucci ◽  
Luisa Schenetti ◽  
Maria A. Vandelli ◽  
Barbara Ruozi ◽  
Flavio Forni
Keyword(s):  
13C Nmr ◽  
Sodium Salt ◽  
Multiple Equilibria ◽  
Diclofenac Sodium ◽  
1H And 13C Nmr ◽  
Nmr Study ◽  
Nmr Techniques ◽  
Nmr Titrations ◽  
C Nmr

The interaction of diclofenac sodium salt (DCFNa) and two cyclodextrins, β-cyclodextrin (βCD) and 2-hydroxypropyl-β-cyclodextrin (HPβCD), studied in D2O solution with different NMR techniques (1H, 13C NMR, ROESY experiments, NMR titrations), shows the existence of multiple equilibria involving 1:1 and 2:1 guest–host complexes.

High-Resolution Latex-State 13C-NMR Spectroscopy for Natural Rubber Vulcanizates

2007 ◽  
Vol 80 (5) ◽  
pp. 751-761 ◽  
Author(s):  
Seiichi Kawahara ◽  
Jinta Ukawa ◽  
Junichiro Sakai ◽  
Yoshimasa Yamamoto ◽  
Yoshinobu Isono
Keyword(s):  
Nmr Spectroscopy ◽  
High Resolution ◽  
Natural Rubber ◽  
13C Nmr ◽  
Multiple Bond ◽  
Natural Rubber Latex ◽  
13C Nmr Spectroscopy ◽  
Rubber Latex ◽  
Aliphatic Carbon ◽  
Natural Rubber Vulcanizates

Abstract Crosslinking junctions of natural rubber vulcanizates were characterized by high-resolution latex-state 13C-NMR spectroscopy. Vulcanized natural rubber latex was prepared by two methods: i.e., vulcanization of the rubber latex and cryogenic crushing of a rubber sheet vulcanized on a hot press. High-resolution latex-state 13C-NMR spectroscopy was attained even after vulcanization of the rubber latex, as is evident from no background in spectrum and narrow half width of signals independent of vulcanization time. Small signals at 44 ppm and 57 ppm in the aliphatic carbon region were assigned by measurements of both Distortionless Enhancement by Polarization Transfer (DEPT) and Attached Proton Test (APT) to secondary and tertiary carbons of crosslinking points. The assignment was proved by high-resolution solution-state NMR spectroscopy of vulcanized liquid cis-1,4-polyisoprene as a model, in which DEPT, APT, 2-dimensional 1H-1H correlation (H-H COSY), 2-dimensional 1H-13C correlation (H-C COSY) and 2-dimensional heteronuclear multiple bond correlation (HMBC) measurements were applied.

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