scholarly journals Full Assignment of Cyano- and Methine-Carbon Peaks in 50 MHz 13C NMR Spectrum and Determination of Sequence Distribution of Acrylonitrile/ Vinylidene Chloride Copolymer

1988 ◽  
Vol 20 (12) ◽  
pp. 1143-1156 ◽  
Author(s):  
Hitoshi Yamazaki ◽  
Kunihiko Okajima ◽  
Kenji Kamide
Keyword(s):  
13C Nmr ◽  
Nmr Spectrum ◽  
Sequence Distribution ◽  
Methine Carbon ◽  
Vinylidene Chloride

Monomer Sequence Distribution in Ethylene—Propylene Rubber Measured by 13C NMR. 3. Use of Reaction Probability Model

1978 ◽  
Vol 51 (2) ◽  
pp. 149-167
Author(s):  
C. J. Carman ◽  
R. A. Harrington ◽  
C. E. Wilkes
Keyword(s):  
13C Nmr ◽  
Probability Model ◽  
Reaction Probability ◽  
Probability Method ◽  
Nmr Spectrum ◽  
Methine Carbon ◽  
Ethylene Propylene ◽  
Monomer Sequence ◽  
Ethylene Propylene Rubber

Abstract One can measure r1r2 for an ethylene—propylene rubber by determining composition and χ, the ratio of contiguous to isolated propylene units. Our previous determination of χ depended on measuring methine carbon resonances in a 13C NMR spectrum. The χ method based solely on methine peak area measurements is inaccurate. This is not because the χ method is theoretically unsound, but because it is impossible to accurately extract the methine areas, necessary to calculate χ from the complex 13C NMR spectra of ethylene—propylene rubbers. The presence of inverted propylene produces ambiguity in a portion of the methine region. This means the methine areas can be used only to calculate a maximum and minimum boundary for r1r2. Another difficulty in using only methine areas to determine χ arises at propylene levels less than 35 wt%, because the methine areas for contiguous propylene triads become very small and are overlapped by strong resonances from long methylene sequences. We have developed a reaction probability method which accurately accounts for all the resonance areas in a 13C NMR spectrum of an ethylene—propylene rubber instead of restricting the analysis to the tertiary carbon areas. The reaction probability method produces a complete calculated 13C NMR spectrum as a best fit to the observed spectrum. The deduced probabilities provide the following derived quantities: (1) “r1r2”, a measure of monomer sequence randomness, (2) the distribution of methylene sequence lengths, (3) composition, (4) amount of propylene inversion. The probabilities can be used to directly calculate “r1r2”. Or alternatively, the probabilities can be used to calculate the methine carbon areas including the separation of the ambiguous methine area into contiguous and isolated contributions. These areas calculated from the probabilities can then be used to determine χ and the resultant r1r2. The two values for r1r2 are in good agreement, lending credence to the probability analysis. The composition derived from probabilities agrees with other analytical methods such as proton NMR and infrared. The limitation of the method is that we cannot accurately determine the percent propylene inversion. We can only conclude that in the majority of the copolymers of 20 to 60 wt% propylene that we have studied, the concentration of inverted propylene is significant and is between 10 and 40% of the total propylene present. Propylene enriched in carbon-13 could be used to prepare copolymers and perhaps resolve this uncertainty.

Sequence Distribution of 1,4-Polybutadienes

1978 ◽  
Vol 51 (2) ◽  
pp. 168-179 ◽  
Author(s):  
Yasuyuki Tanaka ◽  
Hisaya Sato ◽  
Koichi Hatada ◽  
Yoshio Teeawaki ◽  
Hiroshi Okuda
Keyword(s):  
1H Nmr ◽  
13C Nmr ◽  
Sequence Distribution ◽  
Peak Assignment ◽  
Infrared Method ◽  
Sequence Distributions ◽  
Nmr Methods ◽  
In Cis

Abstract The spin-decoupled 1H NMR and 13C NMR methods were employed for the determination of the cis-trans sequence distribution in polybutadiene. Poly(butadiene-2,3-d2) and cis-trans isomerized polybutadienes were used for the peak assignment and the resonance of methylene protons in cis-trans linkage could be described as an A1B2 system. The dyad and triad sequence distributions of cis-1,4 and trans-1,4 units were determined for isomerized, equibinary, and lithium catalyzed polybutadienes, and polycyclooctadienes. The accuracy of the measurements was also studied comparing the results with those by infrared method.

Determination of sequence distribution in 1,4-polybutadiene by 13C-NMR spectra

1974 ◽  
Vol 12 (7) ◽  
pp. 369-373 ◽  
Author(s):  
Yasuyuki Tanaka ◽  
Hisaya Sato ◽  
Masanao Ogawa ◽  
Koichi Hatada ◽  
Yoshio Terawaki
Keyword(s):  
13C Nmr ◽  
Nmr Spectra ◽  
13C Nmr Spectra ◽  
Sequence Distribution

21,22-Disubstituted 18α,19βH-Ursane Derivatives with Oxabicyclooctane System in Ring E

1993 ◽  
Vol 58 (1) ◽  
pp. 173-190 ◽  
Author(s):  
Eva Klinotová ◽  
Jiří Klinot ◽  
Václav Křeček ◽  
Miloš Buděšínský ◽  
Bohumil Máca
Keyword(s):  
Spectral Data ◽  
Spin Systems ◽  
Coupling Constants ◽  
Complete Analysis ◽  
Nmr Spectrum ◽  
Proton Proton ◽  
H Nmr ◽  
Proton Coupling ◽  
C Nmr

Reaction of 3β-acetoxy-21,22-dioxo-18α,19βH-ursan-28,20β-olide (IIIa) and 20β,28-epoxy-21,22-dioxo-19α,19βH-ursan-3β-yl acetate (IIIb) with diazomethane afforded derivatives XII-XIV with spiroepoxide group in position 21 or 22, which were further converted into hydroxy derivatives XV and XVII. Ethylene ketals VIII-X were also prepared. In connection with the determination of position and configuration of the functional groups at C(21) and C(22), the 1H and 13C NMR spectral data of the prepared compounds are discussed. Complete analysis of two four-spin systems in the 1H NMR spectrum of bisethylenedioxy derivative Xb led to the proton-proton coupling constants from which the structure with two 1,4-dioxane rings condensed with ring E, and their conformation, was derived.

scholarly journals Homopiperazine (Hexahydro-1,4-diazepine)

Molbank ◽  
10.3390/m1200 ◽  
2021 ◽  
Vol 2021 (2) ◽  
pp. M1200
Author(s):  
R. Alan Aitken ◽  
Dheirya K. Sonecha ◽  
Alexandra M. Z. Slawin
Keyword(s):  
13C Nmr ◽  
Title Compound ◽  
Coupling Constants ◽  
15N Nmr ◽  
Time Data ◽  
Nmr Spectrum ◽  
X Ray ◽  
First Time

The X-ray structure of the title compound has been determined for the first time. Data on its 1H–13C-NMR coupling constants and 15N-NMR spectrum are also given.

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