Mechanistic Aspects of Polynaphthalimide Synthesis from NMR Analysis

2009 ◽  
Vol 21 (5) ◽  
pp. 624-632 ◽  
Author(s):  
Fabienne Piroux ◽  
Regis Mercier ◽  
Dominique Picq
Keyword(s):  
Model Compound ◽  
Intermediate Compound ◽  
Polycondensation Reaction ◽  
Nmr Analysis ◽  
C Nmr

The mechanism of the polycondensation reaction leading to naphthalimide polymers has been investigated using a model compound. In complement to 19F-NMR analysis, 1H- and 13C-NMR spectroscopies were used to identify the intermediate compound. It was concluded that there was no evidence for the formation of an isoimide, but the formation of an amide—acid intermediate was clearly demonstrated.

A new method for the titration of free phenolic groups in pulps

Holzforschung ◽  
2007 ◽  
Vol 61 (3) ◽  
pp. 242-246 ◽  
Author(s):  
Rabi Behrooz Eshkiki ◽  
Gérard Mortha ◽  
Dominique Lachenal
Keyword(s):  
Kraft Pulp ◽  
Model Compound ◽  
Thermomechanical Pulp ◽  
Stoichiometric Ratio ◽  
Nmr Analysis ◽  
Model Compounds ◽  
Wet Chemical ◽  
Trapping Agent ◽  
C Nmr ◽  
The Ideal

Abstract A fast and semi-quantitative wet chemical method was developed for the titration of free phenolic groups in residual lignins of pulps. The method is based on selective chlorine dioxide reaction with phenolic units of lignin at 0°C. A known amount of ClO2 is reacted for up to 30 min with various substrates and ClO2 consumption is measured. Experiments with monomeric lignin-like model compounds, a dioxane/HCl lignin (isolated from kraft pulp), kraft pulp, and one thermomechanical pulp (TMP) were performed. The ideal stoichiometric consumption of 1 mol of ClO2 per Ar-OH was approximated in a few cases. More model compound experiments are necessary to establish the possibilities and limitations of the method, but the results of these preliminary experiments are promising. First studies on pulps and comparison of the data with those obtained by 13C NMR analysis on dioxane/HCl lignins showed some deviations in the first instance, which were attributed to reaction of the intermediates HClO and Cl2 involved in the overall mechanism. However, using DMSO as HClO trapping agent improved the ClO2/Ar-OH stoichiometric ratio close to the theoretical value of 2, which essentially yielded better results. This improved stoichiometry was verified for three model compounds, one kraft pulp and one TMP, yielding results were similar to those obtained by 13C NMR analysis.

Synthesis and Structure Assignment of 2-(4-Methoxybenzyl)cyclohexyl β-D-Glucopyranoside Enantiomers

2006 ◽  
Vol 71 (10) ◽  
pp. 1470-1483 ◽  
Author(s):  
David Šaman ◽  
Pavel Kratina ◽  
Jitka Moravcová ◽  
Martina Wimmerová ◽  
Zdeněk Wimmer
Keyword(s):  
Analytical Data ◽  
Chiral Hplc ◽  
Nmr Analysis ◽  
Target Structure ◽  
Enantiomerically Pure ◽  
Whole Cells ◽  
H Nmr ◽  
Structure Assignment ◽  
Related Compounds ◽  
C Nmr

Glucosylation of the cis- and trans-isomers of 2-(4-methoxybenzyl)cyclohexan-1-ol (1a/1b, 2a/2b, 1a or 2a) was performed to prepare the corresponding alkyl β-D-glucopyranosides, mainly to get analytical data of pure enantiomers of the glucosides (3a-6b), required for subsequent investigations of related compounds with biological activity. One of the employed modifications of the Koenigs-Knorr synthesis resulted in achieving 85-95% yields of pure β-anomers 3a/3b, 4a/4b, 3a or 4a of protected intermediates, with several promoters and toluene as solvent, yielding finally the deprotected products 5a/5b, 6a/6b, 5a or 6a as pure β-anomers. To obtain enantiomerically pure β-anomers of the target structure (3a, 4a, 5a and 6a) for unambiguous structure assignment, an enzymic reduction of 2-(4-methoxybenzyl)cyclohexan-1-one by Saccharomyces cerevisiae whole cells was performed to get (1S,2S)- and (1S,2R)-enantiomers (1a and 2a) of 2-(4-methoxybenzyl)cyclohexan-1-ol. The opposite enantiomers of alkyl β-D-glucopyranosides (5b and 6b) were obtained by separation of the diastereoisomeric mixtures 5a/5b and 6a/6b by chiral HPLC. All stereoisomers of the products (3a-6b) were subjected to a detailed 1H NMR and 13C NMR analysis.

scholarly journals Biosynthesis of Isoflavonoid Phytoalexins: Incorporation of Sodium [1,2-13C2] Acetate into Phaseollin and Kievitone

1982 ◽  
Vol 37 (5-6) ◽  
pp. 363-368 ◽  
Author(s):  
Paul M. Dewick ◽  
Melanie J. Steele ◽  
Richard A. Dixon ◽  
Ian M. Whitehead
Keyword(s):  
Phaseolus Vulgaris ◽  
Nmr Analysis ◽  
Polyketide Chain ◽  
C Nmr

Abstract13C-NMR analysis of the isoflavonoid phytoalexins phaseollin and kievitone produced by feeding sodium [1,2-13C2]acetate to wounded bean (Phaseolus vulgaris) cotyledons has demonstrated the incorporation of intact acetate units into the aromatic A rings. Phaseollin shows a specific folding of the polyketide chain, whereas kievitone exhibits a randomisation of label in accordance with the intermediacy of a 2′,4′,6′-trihydroxylated chalcone during its formation. In neither case was sufficient label incorporated into analysis.

A route to 24-epibrassinolide from ergosterol avoiding the use of osmium tetroxide

1990 ◽  
Vol 55 (11) ◽  
pp. 2738-2755 ◽  
Author(s):  
Václav Černý ◽  
Miloš Buděšínský
Keyword(s):  
Nmr Spectra ◽  
Osmium Tetroxide ◽  
Model Compound ◽  
Side Chain ◽  
C Nmr

A synthesis of (22R,23R)-2α,3α,22,23-tetrahydroxy-5α-ergostan-6-one (V) from the dienone IV via the diepoxide XXII is described. The tetrol V is a key intermediate in the synthesis of 24-epibrassinolide. The reactivity of the side chain was studied on 5α-ergost-22-en-6-one (XIV) as a model compound. 1H and 13C NMR spectra of 24-epibrassinolide derivatives are discussed.

scholarly journals Noninvasive Measurement of Murine Hepatic Acetyl-CoA13C-Enrichment Following Overnight Feeding with13C-Enriched Fructose and Glucose

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Filipa Carvalho ◽  
Joao Duarte ◽  
Ana Rita Simoes ◽  
Pedro F. Cruz ◽  
John G. Jones
Keyword(s):  
Drinking Water ◽  
Benzoic Acid ◽  
Noninvasive Measurement ◽  
Nmr Analysis ◽  
Acetyl Coa ◽  
Normal Chow ◽  
A Minor ◽  
Pyruvate Recycling ◽  
Amino Benzoic Acid ◽  
C Nmr

The13C-isotopomer enrichment of hepatic cytosolic acetyl-CoA of overnight-fed mice whose drinking water was supplemented with [U-13C]fructose, and [1-13C]glucose andp-amino benzoic acid (PABA) was quantified by13C NMR analysis of urinaryN-acetyl-PABA. Four mice were given normal chow plus drinking water supplemented with 5% [1-13C]glucose, 2.5% [U-13C]fructose, and 2.5% fructose (Solution 1) overnight. Four were given chow and water containing 17.5% [1-13C]glucose, 8.75% [U-13C]fructose and 8.75% fructose (Solution 2). PABA (0.25%) was present in both studies. UrinaryN-acetyl-PABA was analyzed by13C NMR. In addition to [2-13C]- and [1,2-13C]acetyl isotopomers from catabolism of [U-13C]fructose and [1-13C]glucose to acetyl-CoA, [1-13C]acetyl was also found indicating pyruvate recycling activity. This precluded precise estimates of [1-13C]glucose contribution to acetyl-CoA while that of [U-13C]fructose was unaffected. The fructose contribution to acetyl-CoA from Solutions 1 and 2 was 4.0 ± 0.4% and 10.6 ± 0.6%, respectively, indicating that it contributed to a minor fraction of lipogenic acetyl-CoA under these conditions.

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.

1,7-Dioxaspiro[5.5]undecanes. An excellent system for the study of stereoelectronic effects (anomeric and exo-anomeric effects) in acetals

1981 ◽  
Vol 59 (7) ◽  
pp. 1105-1121 ◽  
Author(s):  
Pierre Deslongchamps ◽  
Daryl D. Rowan ◽  
Normand Pothier ◽  
Gilles Sauvé ◽  
John K. Saunders
Keyword(s):  
Experimental Results ◽  
Nmr Analysis ◽  
Steric Interactions ◽  
Stereoelectronic Effects ◽  
Anomeric Effects ◽  
Acid Cyclization ◽  
C Nmr

Several isomeric compounds derived from the spiro systems 5 to 9 (Scheme 4) were obtained from the acid cyclization of the appropriate dihydroxy ketone precursor.The configuration and the conformation of the products obtained was determined by 13C nmr analysis and equilibration studies. The experimental results can be rationalized by taking into account the anomeric and the exo-anomeric effects and the usual steric interactions.

scholarly journals Fast Catalytic Pyrolysis of Dilaurin in the Presence of Sodium Carbonate Alone or Combined with Alumina

Catalysts ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 993 ◽  
Author(s):  
Noyala Fonseca ◽  
Aline Pereira ◽  
Roger Fréty ◽  
Emerson Sales
Keyword(s):  
Sodium Carbonate ◽  
Catalytic Pyrolysis ◽  
Model Compound ◽  
Raw Materials ◽  
Fatty Acid Content ◽  
Fast Pyrolysis ◽  
Intermediate Compound ◽  
Liquid Fuels ◽  
Catalytic Reactor ◽  
Total Conversion

The objective of this work was to study the fast pyrolysis of a diglyceride intermediate compound during the conversion of triglycerides to fatty acids, esters and/or hydrocarbons. Dilaurin was selected as a model compound. Pyrolysis was conducted in a micro-pyrolyzer coupled to GC-MS equipment at 500, 550 and 600 °C for 15 s in the presence of sodium carbonate (Na2CO3) as the catalyst. Results were compared to pyrolysis data using γ-Al2O3 as a catalyst. At 600 °C with Na2CO3 almost total conversion of diglyceride was obtained, with the formation of 41.3% hydrocarbons (C3 to C13). In the same conditions using alumina as a catalyst 68.5% of hydrocarbons were obtained. Na2CO3 presented itself as an efficient feedstock modifier, allowing pre-cracking and partial deoxygenation of the load. The use of the Na2CO3 and γ-Al2O3 conjugated system in layers reduced the fatty acid content in the products, increasing both the reagent conversion and the hydrocarbon variety (C3 to C23). This work suggests that the use of a double bed catalytic reactor is suitable for performing a deoxygenating pretreatment and producing hydrocarbons compatible with current liquid fuels, being potentially useful for more complex raw materials such as those from biomass treatments.

scholarly journals Kernresonanzspektroskopische Untersuchungen an t-Butyl-phenyl-phosphinsäure-(—)-menthylester, II [1]1H-, 13C-und 31P-NMR-Analyse der absoluten Konfiguration am Phosphoratom / NMR Spectroscopic Investigations on t-Butyl-phenyl-phosphinic Acid(—)-Menthyl Ester, II [1] 1H, 13C and 31P NMR Analysis of Absolute Configuration at the Phosphorus Center

1980 ◽  
Vol 35 (10) ◽  
pp. 1182-1190 ◽  
Author(s):  
Gerhard Hägele ◽  
Detlef Wendisch ◽  
Reiner Luckenbach ◽  
Hans-H. Bechtolsheimer
Keyword(s):  
Absolute Configuration ◽  
Nmr Spectra ◽  
31P Nmr ◽  
Double Resonance ◽  
Phosphinic Acid ◽  
Nmr Analysis ◽  
Spectroscopic Investigations ◽  
Phosphinic Acids ◽  
13C And 31P Nmr ◽  
C Nmr

Abstract(-)-Menthol, Diastereomeric Menthylesters of Phosphinic Acids, 31P NMR Spectra, 13C NMR Spectra, Double Resonance(-)-Menthol and diastereomeric (-)-menthyl esters of t-butyl-phenyl-phosphinic acid are investigated by means of 1H, 13C and 31P NMR at 2.1 and 8.4. Tesla double resonance experiments are described.

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