13C Nuclear Magnetic Resonance Spectroscopy of Polydienes, Micro Structure of Poly(Butadiene)

1974 ◽  
Vol 47 (5) ◽  
pp. 1136-1150
Author(s):  
A. D. H. Clague ◽  
J. A. M. van Broekhoven ◽  
L. P. Blaauw
Keyword(s):  
Nmr Spectra ◽  
Resonance Spectroscopy ◽  
13C Nmr Spectra ◽  
Constant Ratio ◽  
Micro Structure ◽  
Sequence Distribution ◽  
13C Nuclear Magnetic Resonance ◽  
Random Manner ◽  
Cis And Trans ◽  
Detailed Picture

Abstract 13C nmr spectra have been recorded of several poly(butadiene)s and their hydrogenated analogs, with various amounts of 1,2 structure, but with a roughly constant ratio of cis-1,4 to trans-1,4 structures. From an assignment of these spectra a detailed picture has emerged of the sequence distribution of the cis- and trans-1,4 and the 1,2 units in the poly (butadiene) chain. It is shown that these units are distributed in an essentially random manner and that 1,2 units are head to tail incorporated.

scholarly journals Study of the biologically active acyclic ureas by nuclear magnetic resonance

2020 ◽  
Vol 100 (4) ◽  
pp. 60-74
Author(s):  
А.А. Bakibaev ◽  
◽  
М.Zh. Sadvakassova ◽  
V.S. Malkov ◽  
R.Sh. Еrkasov ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Functional Groups ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Biologically Active ◽  
Resonance Spectroscopy ◽  
13C Nmr Spectra ◽  
Nuclear Magnetic

A wide variety of acyclic ureas comprising alkyl, arylalkyl, acyl, and aryl functional groups are investigated by nuclear magnetic resonance spectroscopy. In general, spectral characteristics of more than 130 substances based on acyclic ureas dissolved in deuterated dimethyl sulfoxide at room temperature are studied. The re-sults obtained based on the studies of 1H and 13C NMR spectra of urea and its N-alkyl-, N-arylalkyl-, N-aryl- and 1,3-diaryl derivatives are presented, and the effect of these functional groups on the chemical shifts in carbonyl and amide moieties in acyclic urea derivatives is discussed. An introduction of any type of substitu-ent (electron-withdrawing or electron-donating) into urea molecule is stated to result in a strong upfield shift in 13C NMR spectra relatively to unsubstituted urea. A strong sensitivity of NH protons to the presence of acyl and aryl groups in nuclear magnetic resonance spectra is pointed out. In some cases, qualitative depend-encies between the chemical shifts in the NMR spectra and the structure of the studied acyclic ureas are re-vealed. A summary of the results on chemical shifts in the NMR spectra of the investigated substances allows determining the ranges of chemical shift variations of the key protons and carbon atoms in acyclic ureas. The literature describing the synthesis procedures are provided. The results obtained significantly expand the methods of reliable identification of biologically active acyclic ureas and their metabolites that makes it promising to use NMR spectroscopy both in biochemistry and in clinical practice.

scholarly journals 1H- und C-NMR-Spektren von Methoxy-substituierten Äthylenen / 1H and 13C NMR Spectra of Methoxy-substituted Ethylenes

1976 ◽  
Vol 31 (1) ◽  
pp. 35-38 ◽  
Author(s):  
M. Herberhold ◽  
G. O. Wiedersatz ◽  
C. G. Kreiter
Keyword(s):  
Charge Distribution ◽  
Vinyl Ether ◽  
13C Nmr ◽  
Nmr Spectra ◽  
13C Nmr Spectra ◽  
1H And 13C Nmr ◽  
Methyl Vinyl ◽  
Methyl Vinyl Ether ◽  
Cis And Trans ◽  
C Nmr

The charge distribution in the methoxy -substituted olefins of the series ethylene, methyl vinyl ether, 1,1-dimethoxyethylene, cis- and trans-dimethoxyethylene, tetramethoxyethylene, is discussed on the basis of the 1H and 13C NMR spectra

13C nuclear magnetic resonance spectroscopy of methylenedioxy group-containing C19-diterpenoid alkaloids and their derivatives

1980 ◽  
Vol 58 (17) ◽  
pp. 1875-1879 ◽  
Author(s):  
S. William Pelletier ◽  
Naresh V. Mody ◽  
Oliver D. Dailey Jr.
Keyword(s):  
Structure Elucidation ◽  
Nmr Spectra ◽  
Structural Changes ◽  
Single Frequency ◽  
Resonance Spectroscopy ◽  
Diterpenoid Alkaloids ◽  
Methylenedioxy Group ◽  
13C Nuclear Magnetic Resonance ◽  
Self Consistent ◽  
Proton Decoupling

The natural abundance carbon-13 nmr spectra of some methylenedioxy group-containing C19-diterpenoid alkaloids and their derivatives (dictyocarpine, 14-acetyldictyocarpine, dictyocarpinine, 14-dehydrodictyocarpine, 14-dehydrodictyocarpinine, 6-dehydrodictyocarpinine, 6,14-didehydrodictyocarpinine, deltaline (eldeline), deltamine (eldelidine), 6-dehydrodeltamine, delcorine, 6-acetyldelcorine, and 6-dehydrodelcorine) have been determined. Self-consistent assignments of nearly all the resonances in these compounds have been made with the aid of single-frequency off-resonance proton decoupling techniques, additivity relationships, and the effects induced by certain structural changes. Particular attention is directed towards features of the spectra which are most useful for structure elucidation and identification of the C19-diterpenoid alkaloids.

Analysis of tricarboxylic acid cycle of the heart using 13C isotope isomers

1990 ◽  
Vol 259 (3) ◽  
pp. H987-H995 ◽  
Author(s):  
C. R. Malloy ◽  
A. D. Sherry ◽  
F. M. Jeffrey
Keyword(s):  
13C Nmr ◽  
Nmr Spectra ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
13C Nmr Spectra ◽  
Acid Cycle ◽  
Rat Hearts ◽  
13C Nuclear Magnetic Resonance ◽  
Peak Areas

13C-nuclear magnetic resonance (NMR) spectroscopy provides a new approach to the analysis of metabolic pathways, because it detects an interaction between adjacent 13C nuclei. Previous models of isotope distribution in the tricarboxylic acid cycle were designed for analysis of radioisotope data and did not consider the information provided by 13C-13C coupling. A mathematical model of the tricarboxylic acid cycle was developed that preserves all isotope isomer (isotopomer) information and yields simple relationships between 13C-NMR spectra of glutamate and metabolic parameters under steady-state conditions. With the use of relative peak areas measured from the spectra of tissues supplied with 13C-enriched substrate(s), the relative fluxes through both oxidative (acetyl-CoA utilization) and nonoxidative (anaplerotic) pathways of the tricarboxylic acid cycle can be determined. Furthermore, with the judicious selection of 13C-labeling patterns in a mixture of substrates, direct substrate competition experiments can be performed. The perchloric acid extracts of Langendorff and working rat hearts oxidizing 13C-enriched fatty acids or carbohydrates are analyzed to illustrate this approach, and the importance of measuring the fractional enrichment of the available substrate is demonstrated. The technique can of course be used with all tissues, not just heart, and is applicable to the analysis of in vivo 13C-NMR spectra.

Sequence Distribution of cis-1,4- and trans-1,4-Units in Polyisoprenes

1976 ◽  
Vol 49 (5) ◽  
pp. 1269-1275
Author(s):  
Y. Tanaka ◽  
H. Sato
Keyword(s):  
Nmr Spectroscopy ◽  
13C Nmr ◽  
Nmr Spectra ◽  
13C Nmr Spectroscopy ◽  
13C Nmr Spectra ◽  
Sequence Distribution ◽  
Isomeric Structures ◽  
Nmr Signals

Abstract Recently 13C NMR spectroscopy has been successfully applied to investigate the sequence distribution of 1,2- and 1,4-units or cis-1,4- and trans-1,4-units in polybutadienes. As for polyisoprenes, however, few investigations have been made on the sequence distribution of isomeric structures using this technique, although Duch and Grant have assigned the 13C NMR signals of cis-1,4- and trans-l,4-homopolyisoprenes. In previous work we have found new signals attributed to cis-trans linkages in the 13C NMR spectra of cis-trans isomerized polyisoprenes and assigned the signals using diad sequences of cis-1,4- and trans-l,4-units. We have also studied the 13C NMR spectra of hydrogenated polyisoprenes containing various amounts of 1,4- and 3,4-units and the sequence distribution of 1,4- and 3,4-units were discussed for n-BuLi-catalyzed polyisoprenes. In this work we have investigated the sequence distribution of chicle polyisoprene and cis-trans isomerized 1,4-polyisoprenes containing various ratios of cis-1,4- and trans-1,4-units.

Sequence Distribution of Polyisoprenes

1976 ◽  
Vol 49 (5) ◽  
pp. 1259-1268 ◽  
Author(s):  
Y. Tanaka ◽  
H. Sato
Keyword(s):  
13C Nmr ◽  
Nmr Spectra ◽  
Polymer Chains ◽  
Absolute Amount ◽  
Mechanical And Thermal Properties ◽  
13C Nmr Spectra ◽  
Pyrolysis Gas ◽  
Sequence Distribution ◽  
The Difference ◽  
Isomeric Structures

Abstract Isoprene can be polymerized into four types of isomeric structures; cis-1,4, trans-1,4, 3,4, and 1,2, depending on catalysts and polymerization conditions. So far, the difference of mechanical and thermal properties among polyisoprenes has been discussed chiefly on the basis of amounts of these isomeric structures. However, it is quite reasonable to expect that the polymer properties are affected not only by the composition of isomeric structures but also by the distribution of isomeric structures, the arrangement of head and tail linkages, and the degree of branching. This idea was adopted by Hackathorn and Brock as an explanation of the poor crystallizability of lithium polyisoprene; i.e. head-to-head and/or tail-to-tail linkages of 1,4- and 3,4-units prevented the crystallization of the polymer. Pyrolysis-gas chromatography has been applied to the investigation of the sequence distribution of 1,4- and 3,4-units in polyisoprenes. This method is based on the structural relationship between the isoprene dimers and the diad sequences of 1,4- and 3,4-units. However, it is difficult to discuss the slight differences in the yield of each dimer because the absolute amount of the dimers is small (∼30%) compared to the isoprene monomer (∼65%). Ozonolysis has been used to measure the amount of head-to-head, head-to-tail, and tail-to-tail linkages of the 1,4-unit in polyisoprenes. This method, however, is limited to the detection of these linkages of 1,4-units. In a previous paper, we have investigated 13C NMR spectra of chicle and cis-trans isomerized polyisoprenes and determined the sequence distribution of cis-1,4- and trans- 1,4-units in these polymers. We have also studied 13C NMR spectra of hydrogenated polyisoprenes prepared with n-BuLi-Et2O catalysts and found that 1,4- and 3,4-units were distributed randomly along the polymer chains regardless of the amounts of 3,4-units. In the present investigation we prepared various types of polyisoprenes and discussed the distribution of 1,4-and 3,4-units, arrangements of head and tail linkages, the branches of polymer chains, and the tacticity of polyads of 3,4-unit by the use of 13C NMR spectra of hydrogenated polyisoprenes.

1H and 13C NMR spectra of cis and trans phytoene isomers

1973 ◽  
Vol 10 (1) ◽  
pp. 43-50 ◽  
Author(s):  
P Granger ◽  
B Maudinas ◽  
R Herber ◽  
J Villoutreix
Keyword(s):  
13C Nmr ◽  
Nmr Spectra ◽  
13C Nmr Spectra ◽  
1H And 13C Nmr ◽  
Cis And Trans
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