Chemical Structures of (+)-Catechin-Formaldehyde Reaction Products (Stiasny Precipitates) Under Strong Acid Conditions: Part 1. Solid-State 13C-NMR Analysis

Holzforschung ◽  
2001 ◽  
Vol 55 (2) ◽  
pp. 205-213 ◽  
Author(s):  
N. Saito ◽  
M. Reilly ◽  
Y. Yazaki
Keyword(s):  
Solid State ◽  
Chemical Shifts ◽  
Strong Acid ◽  
Radiata Pine ◽  
Reaction Products ◽  
Nmr Spectrum ◽  
Chemical Structures ◽  
13C Nmr Analysis ◽  
C Nmr ◽  
Solid State 13C Nmr

Summary To determine more accurately the amount of polyflavanoids in tannin extracts from radiata pine bark, which react with formaldehyde, it is important to elucidate chemical structures of (﹢)-catechin-formaldehyde reaction products (Stiasny precipitates). The Stiasny value of 106.4% for (﹢)-catechin was obtained from the reaction with formaldehyde under strong acid conditions. This value is almost identical to the value calculated from the Stiasny precipitates, which were formed in the ratio of two molecules of (﹢)-catechin to three molecules of formaldehyde. The solid-state 13C NMR spectrum was measured to elucidate the structures of the Stiasny precipitates, and analysed on the basis of the chemical shifts of (﹢)-catechin. The NMR results indicate that C-6 and C-8 in the A-ring are bonded by methylene bridges to form polymers, and also form methylene bridges with C2′, C5′ or C6′ in the B-ring of a catechin unit. Consequently, the reaction products of (﹢)-catechin-formaldehyde under strong acid conditions (Stiasny precipitates) are (﹢)-catechin-polymers, which consist of two moles of (﹢)-catechin and three moles of formaldehyde. The methylene bridges are formed mostly between A-rings, and less frequently, between A- and B-rings and between B-rings of the catechin units.

Synthesis, X-ray crystal structure, and solid-state 13C NMR study of tris(9-crown-3)triphenylene

2001 ◽  
Vol 79 (2) ◽  
pp. 195-200 ◽  
Author(s):  
Gerald W Buchanan ◽  
Majid F Rastegar ◽  
Glenn PA Yap
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Crown Ether ◽  
Chemical Shifts ◽  
Aromatic Rings ◽  
X Ray ◽  
Nmr Study ◽  
Group A ◽  
C Nmr ◽  
Solid State 13C Nmr

Benzo-9-crown-3 ether trimerizes in the presence of FeCl3 and aqueous H2SO4 to produce tris(9-crown-3)triphenylene in 25.4% yield. This compound crystallizes in the monoclinic P21/c space group: a = 13.759(2) Å, b = 13.318(2) Å, c = 13.399(2) Å, β = 96.883(2)°, with Z = 4. The three 9-crown-3 ether units of the trimer possess different geometries and there is substantial deviation from coplanarity in the three aromatic rings. 13C NMR chemical shifts in the solid state are consistent with this lack of symmetry and are discussed in terms of the X-ray crystal-structure data.Key words: crown ether, trimerization, stereochemistry.

Solid state stereochemistry of crown ethers: X-ray crystal structure and 13C NMR studies of the LiNCS complex of 1,4,7,11-tetraoxacyclotetradecane

2000 ◽  
Vol 78 (3) ◽  
pp. 316-321
Author(s):  
G W Buchanan ◽  
A B Driega ◽  
G PA Yap
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Crown Ether ◽  
13C Nmr ◽  
Title Complex ◽  
Nmr Studies ◽  
Nmr Spectrum ◽  
X Ray ◽  
Large Amplitude Motion ◽  
C Nmr

The title complex is asymmetric in the crystal due to the spatial orientation of the NCS function. The space group has been determined to be P21 with a = 9.496(3), b = 8.736(3), c = 9.676(3) Å, β = 117.859(5)°, and Z = 2. The solid state 13C NMR spectrum is consistent with the lack of symmetry in the crystal and there is little evidence for large amplitude motion in the macrocycle as determined from the dipolar dephased spectrum.Key words: macrocyclic crown ether, lithium complex.

Synthetic, Infrared, 1H and 13C NMR Spectral Studies on N-(2/3/4-Substituted Phenyl)-2,4-Disubstituted Benzenesulphonamides, 2,4-(CH3)2/2-CH3-4-Cl/2,4-Cl2C6H3SO2NH(i-XC6H4) (i-X = H, 2-CH3, 3-CH3, 4-CH3, 2-Cl, 3-Cl, 4-Cl, 4-F, 4-Br)

2006 ◽  
Vol 61 (10-11) ◽  
pp. 600-606
Author(s):  
Savitha M. Basappa ◽  
Basavalinganadoddy Thimme Gowda
Keyword(s):  
Solid State ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Spectral Studies ◽  
1H And 13C Nmr ◽  
Nmr Chemical Shifts ◽  
Benzene Rings ◽  
Stretching Vibrations ◽  
Absorption Frequencies ◽  
C Nmr

Twenty six N-(2/3/4-substituted phenyl)-2,4-disubstituted benzenesulphonamides of the general formulae 2,4-(CH3)2C6H3SO2NH(i-XC6H4), 2-CH3-4-ClC6H3SO2NH(i-XC6H4) and 2,4- Cl2C6H3SO2NH(i-XC6H4), where i-X = H, 2-CH3, 3-CH3, 4-CH3, 2-Cl, 3-Cl, 4-Cl, 4-F or 4-Br, have been prepared, characterized and their infrared spectra in the solid state and 1H and 13C NMR spectra in solution studied. The infrared N-H stretching vibrational frequencies vary in the range 3298 - 3233 cm−1. Asymmetric and symmetric SO stretching vibrations appear in the ranges 1373 - 1311 cm−1 and 1177 - 1140 cm−1, respectively, while C-S, S-N and C-N stretching absorptions vary in the ranges 840 - 812 cm−1, 972 - 908 cm−1 and 1295 - 1209 cm−1, respectively. The various 1H and 13C NMR chemical shifts are assigned to the protons and carbon atoms of the two benzene rings in line with those for similar compounds. The incremental shifts due to the groups in the parent compounds have been computed by comparing the chemical shifts of the protons or carbon atoms in these compounds with those of benzene or aniline, respectively. The computed incremental shifts and other data were used to calculate the 1H and 13C NMR chemical shifts of the substituted compounds in three different ways. The calculated chemical shifts by the three methods compared well with each other and with the observed chemical shifts. It is observed that there are no particular trends in the variation of either the infrared absorption frequencies or the chemical shifts with the nature or site of substitution.

Oxidative coupling of naphtho-9-crown-3 ether: X-ray crystal structure and solution and solid-state NMR analysis of the dimer

2001 ◽  
Vol 79 (10) ◽  
pp. 1505-1510 ◽  
Author(s):  
G W Buchanan ◽  
M F Rastegar ◽  
G PA Yap ◽  
A Moghimi ◽  
M Ghandi
Keyword(s):  
Solid State ◽  
Oxidative Coupling ◽  
Solid State Nmr ◽  
Nmr Analysis ◽  
Oxidative Dimerization ◽  
Nmr Spectrum ◽  
X Ray ◽  
Nmr Data ◽  
Group A ◽  
C Nmr

Treatment of naphtho-9-crown-3 ether with FeCl3 and aqueous H2SO4 generates bis-naphtho-9-crown-3 ether in ca. 30% yield. This compound crystallizes in the monoclinic P21/n space group; a = 9.2004(9), b = 18.0868(17), and c = 13.2078(13) Å, β = 97.799(2)° and Z = 4. 1H and 13C NMR data have been obtained in solution, and the solid-state 13C NMR spectrum is included for comparison. A chemical shift range of ca. 12 ppm has been found for the oxygenated aliphatic carbons in the solid state, in contrast to the 3 ppm range in the solution 13C NMR spectrum. These results are discussed in terms of the torsional environments of the carbon sites in the crystal structure.Key words: crown ether, stereochemistry, oxidative dimerization.

scholarly journals Perfect and Defective 13C-Furan-Derived Nanothreads from Modest-Pressure Synthesis Analyzed by 13C NMR

2021 ◽  
Author(s):  
Bryan Matsuura ◽  
Steven Huss ◽  
zhaoxi zheng ◽  
Shichen Yuan ◽  
Tao Wang ◽  
...  
Keyword(s):  
Spin Diffusion ◽  
Periodic Structures ◽  
Chemical Shifts ◽  
Polarization Spectrum ◽  
High Symmetry ◽  
Reaction Products ◽  
Pressure Synthesis ◽  
Isotropic Chemical Shifts ◽  
Almost All ◽  
C Nmr

<p><sup>13</sup>C-enrichment of furan by custom synthesis followed by modest-pressure synthesis of <sup>13</sup>C-enriched nanothreads enabled a detailed characterization of the reaction products by a full complement of advanced solid-state NMR techniques, with validation by <i>ab initio</i> calculation of chemical shifts. The <sup>13</sup>C NMR spectrum was complex, with more than a dozen distinct features, but almost all (> 95%) represented CH moieties are as expected in nanothreads, with only 2–4% CH<sub>2</sub>, 0.3% C=O, and 0.3% COO groups, according to spectral editing. Different components were quantified by integration of the fully equilibrated direct-polarization spectrum. Symmetric and asymmetric alkene-containing rings as well as trapped furan were identified by <sup>13</sup>C-<sup>13</sup>C and <sup>1</sup>H-<sup>13</sup>C NMR. The most intriguing component observed was fully saturated perfect <i>anti</i> furan-derived nanothread segments, with two distinct, sharp peaks, accounting for ca. 10% of the material. The bonding patterns in these periodic structures deduced from DQ/SQ NMR was that of a [4+2] cycloaddition product. While the small number of chemically inequivalent carbon sites eliminated low-symmetry <i>syn/anti</i> threads, the large number of magnetically inequivalent ones (<i>i.e.,</i> distinct C-H orientations) in CODEX NMR was incompatible with the high-symmetry <i>syn</i> threads. <i>Anti</i> threads with two chemically and eight magnetically inequivalent sites provide the only consistent fit of the experimental data. These conclusions were convincingly corroborated by quantum-chemical simulations, which showed good agreement of isotropic chemical shifts only for the <i>anti</i> threads. This represents the first molecular-level identification of a specific type of nanothread. The typical length of the perfect, fully saturated thread segments was around 14 bonds and they accordingly constitute small clusters (according to <sup>13</sup>C and <sup>1</sup>H spin diffusion analyses) which likely reside within an overall hexagonal thread packing along with other, less-perfect or less-saturated brethren. The relatively slow <i>T</i><sub>1C</sub> relaxation confirms the nanometer-scale length of the periodic perfect structure, indicates that the perfect threads are particularly rigid, and enables their selective observation in <sup>13</sup>C NMR. </p>

29Si, 13C and 31P NMR spectra of silicon-substituted ω-diphenylphosphinoalkyl silanes, (CH3)3-n(OC2H5)nSi(CH2)mP(C6H5)2

1982 ◽  
Vol 47 (3) ◽  
pp. 793-801 ◽  
Author(s):  
Jan Schraml ◽  
Martin Čapka ◽  
Harald Jancke
Keyword(s):  
Nmr Spectra ◽  
31P Nmr ◽  
Chemical Shifts ◽  
Additivity Rule ◽  
Ethoxy Group ◽  
Spectral Parameters ◽  
Nmr Spectrum ◽  
Nmr Parameters ◽  
13C And 31P Nmr ◽  
C Nmr

29Si, 13C, and 31P NMR spectra of a series of compounds of the structure (CH3)3-n(C2H5O)n.Si(CH2)mP(C6H5)2 (m = 1-6, n = )-3) are reported and assigned. Using monodeutero derivative of the compound with m = 3 and n = 0 an earlier assignment of 13C NMR spectrum is confirmed, but the assignment in the compounds with m = 4 is reversed. Introduction of ethoxy groups leads to violation of additivity rule for the 13C chemical shifts in the derivatives with m = 1. In all derivatives presence of one ethoxy group in the molecule has a profound effect on 31P chemical shift which is not changed by any further increase in the number of ethoxy groups in the molecule. The changes in 29Si chemical shifts follow the pattern known from other series of compounds. The observed trends in NMR parameters with changing n and m values can be explained by an interaction between phosphorus and oxygen atoms. Possible connections between the spectral parameters and catalysis employing the studied compounds are discussed.

A solid-state 13C NMR analysis of molecular dynamics in aramide polymers

2006 ◽  
Vol 29 (1-3) ◽  
pp. 132-141 ◽  
Author(s):  
Dan McElheny ◽  
Veronica Frydman ◽  
Lucio Frydman
Keyword(s):  
Molecular Dynamics ◽  
Solid State ◽  
13C Nmr ◽  
Nmr Analysis ◽  
13C Nmr Analysis ◽  
Solid State 13C Nmr

scholarly journals Solid-State 13C NMR Analysis of the Crystalline–Noncrystalline Structure and Chain Conformation of Thermotropic Liquid Crystalline Polyester

2004 ◽  
Vol 36 (10) ◽  
pp. 830-840 ◽  
Author(s):  
Miwa Murakami ◽  
Hiroyuki Ishida ◽  
Hironori Kaji ◽  
Fumitaka Horii ◽  
Masatoshi Tokita ◽  
...  
Keyword(s):  
Solid State ◽  
13C Nmr ◽  
Liquid Crystalline ◽  
Chain Conformation ◽  
Nmr Analysis ◽  
13C Nmr Analysis ◽  
Liquid Crystalline Polyester ◽  
Solid State 13C Nmr

The in situ analysis of organic matter in soils

2001 ◽  
Vol 81 (3) ◽  
pp. 249-254 ◽  
Author(s):  
Morris Schnitzer
Keyword(s):  
Mass Spectrometry ◽  
Organic Matter ◽  
Solid State ◽  
In Situ Analysis ◽  
Ionization Mass Spectrometry ◽  
Field Ionization ◽  
Ionization Mass ◽  
Chemical Structures ◽  
C Nmr

Traditionally, studies on soil organic matter (SOM) begin with the extraction of SOM from soils, its fractionation into humic acid, fulvic acid, and humin, followed by de-ashing of each fraction. These are tedious, laborious and inefficient procedures that do not provide any chemical information on these materials. Instead, recently developed methods such as solid-state 13C NMR and pyrolysis – field ionization mass spectrometry (Py-FIMS) can now be used for the in situ analysis of SOM in soils. These methods identify the major chemical components of SOM without extractions and fractionations, and yield valuable information on the main chemical structures in these materials. A better knowledge of the structural chemistry of SOM will help SOM chemists and other soil scientists to better understand the complex chemical and biochemical reactions that occur in soils, and will enable them to develop practices that will improve soil management and soil productivity. Key words: Extraction, fractionation, solid state 13C NMR, pyrolysis-field ionization mass spectrometry, chemical composition

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