Analysis of lignin and extractives in the oak wood of the 17th century warship Vasa

Holzforschung ◽  
2014 ◽  
Vol 68 (4) ◽  
pp. 419-425 ◽  
Author(s):  
Dina Dedic ◽  
Teresia Sandberg ◽  
Tommy Iversen ◽  
Tomas Larsson ◽  
Monica Ek
Keyword(s):  
Oxidative Degradation ◽  
Magic Angle Spinning ◽  
Chemical Degradation ◽  
Gas Chromatography Mass Spectrometry ◽  
Magic Angle ◽  
Chemical Mechanisms ◽  
Wood Extracts ◽  
Cellulose Depolymerization ◽  
Angle Spinning ◽  
C Nmr

Abstract The wood in the 17th century Swedish warship Vasa is weak. A depolymerization of the wood’s cellulose has been linked to the weakening, but the chemical mechanisms are yet unclear. The objective of this study was to analyze the lignin and tannin moieties of the wood to clarify whether the depolymerization of cellulose via ongoing oxidative mechanisms is indeed the main reason for weakening the wood in the Vasa. Lignin was analyzed by solid-state nuclear magnetic resonance [cross-polarization/magic-angle spinning (CP/MAS) 13C NMR] and by means of wet chemical degradation (thioacidolysis) followed by gas chromatography-mass spectrometry (GC-MS) of the products. No differences could be observed between the Vasa samples and the reference samples that could have been ascribed to extensive lignin degradation. Wood extracts (tannins) were analyzed by matrix-assisted laser desorption ionization (MALDI) combined with time-of-flight (TOF) MS and 13C NMR spectroscopy. The wood of the Vasa contained no discernible amounts of tannins, whereas still-waterlogged Vasa wood contained ellagic acid and traces of castalagin/vescalagin and grandinin. The results indicate that the condition of lignin in the Vasa wood is similar to fresh oak and that potentially harmful tannins are not present in high amounts. Thus, oxidative degradation mechanisms are not supported as a primary route to cellulose depolymerization.

A 13C and 15N nuclear magnetic resonance study of solid ammonium thiocyanate

1987 ◽  
Vol 65 (5) ◽  
pp. 941-946 ◽  
Author(s):  
Ross M. Dickson ◽  
Michael S. McKinnon ◽  
James F. Britten ◽  
Roderick E. Wasylishen
Keyword(s):  
Ammonium Thiocyanate ◽  
Nuclear Magnetic Resonance Study ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Chemical Shielding ◽  
X Ray ◽  
Shielding Constants ◽  
Angle Spinning ◽  
Good Agreement ◽  
C Nmr

The static 13C nmr powder pattern for solid ammonium thiocyanate is analyzed to obtain the 13C chemical shielding anisotropy, 321 ± 7 ppm, and the 13C–14N dipolar splitting, 1295 ± 25 Hz. Slow magic angle spinning 15N nmr experiments are analyzed to obtain a nitrogen chemical shielding anisotropy of 415 ± 15 ppm. The 13C–14N dipolar splitting leads to an effective C—N bond length of 1.19 ± 0.01 Å, in good agreement with the value of 1.176 Å reported from accurate X-ray and neutron crystallographic studies. In solid NH4NCS absolute values of the average shielding constants [Formula: see text] and ct[Formula: see text] are 52 and 34 ppm, respectively. Comparison of calculated and observed [Formula: see text] values indicates that intermolecular interactions decrease the 13C and 15N shielding constants by approximately 10 and 30 ppm, respectively.

Carbon-13 CP/MAS NMR and DR-FTIR spectroscopic studies of sugarcane distillery waste

1998 ◽  
Vol 78 (1) ◽  
pp. 227-236 ◽  
Author(s):  
M. B. Benke ◽  
A. R. Mermut ◽  
B. Chatson
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Fourier Transform ◽  
Organic Carbon ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Cross Polarization ◽  
Distillery Waste ◽  
Angle Spinning ◽  
Cp Mas Nmr ◽  
C Nmr

The application of a sugarcane distillery waste known as vinasse to agricultural land has become a common practice in Brazil. The vinasse samples used in this study were collected from several sugarcane distilleries in Northeastern Brazil. These samples were fractionated into dissolved organic carbon (DOC) and particulate organic carbon (POC) fractions. Unfractionated and fractionated vinasse were studied using 13C cross-polarization and magic-angle spinning nuclear magnetic resonance (CP/MAS NMR) spectroscopy as well as diffuse reflectance Fourier-transform infrared (DR-FTIR) spectroscopy. Approximately 79 to 92% of the total unfractionated vinasse dry matter was in the form of DOC fraction. O-alkyl C (42–53% of the total C) and carboxyl C (12–25% of the total C) comprised a significant portion of the 13C NMR spectra of the DOC fraction. The presence of carbohydrates and COOH/COO− was suggested by the DR-FTIR as well. Both 13C NMR and DR-FTIR spectra of this fraction were generally similar to the spectra of the fulvic acid (FA) fraction of soil and sewage sludge. The spectra of DOC differed from the FA fraction in that they showed smaller amounts of aromatic C and had an absence of amide group (bands at 1650 cm−1 and 1540 cm−1). In the POC fraction, O-alkyl (17–52% of the total C) and alkyl C (15–41% of the total C) were the major contributors. The peaks at 62 ppm, 72 ppm, 84 ppm and 105 ppm in the O-alkyl region indicate the presence of cellulose and/or hemicellulose. The alkyl group was comprised mainly of long-chain structures. The total N content in this fraction is ~3–7 times as much as in the DOC fraction. The presence of amino acids in the POC fraction was suggested by both 13C NMR and DR-FTIR spectra. Key words:13C cross-polarization and magic-angle spinning nuclear magnetic resonance, dissolved organic carbon, Fourier-transform infrared, particulate organic carbon, vinasse

Cocation Effects in Rhodium-Exchanged Y Zeolites

1987 ◽  
Vol 111 ◽  
Author(s):  
R. K. Shoemaker ◽  
R. A. Johnson ◽  
T. M. Apple
Keyword(s):  
Room Temperature ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Internuclear Separation ◽  
Y Zeolites ◽  
Yield Information ◽  
Acid Centers ◽  
Angle Spinning ◽  
Metal Electron ◽  
C Nmr

AbstractMagic-angle spinning13C NMR spectra of carbon monoxide adsorbed on rhodium/Y zeolites yield information about the proportioning of CO in the various possible adsorption states; linear, bridged and dicarbonyl. The relative amounts of these adsorbed types, particularly the ratio of bridged to linear CO is influenced by the nature of the majority cations present with the rhodium. Reduced Rh-Na(+) and Rh-Li(+) zeolites form all three CO surface species, while acidic Rh zeolites, formed by the introduction of the co-cations Ca(2+) and H(+), exhibit no bridged carbonyls. The suppression of the bridged moiety results from the withdrawal of electrons from rhodium by the acid centers making the metal electron deficient (more oxidized).Rh(I) dicarbonyl species form on all samples studied, however these species are indistinguishable from the linear monocarbonyls based solely upon the isotropic chemical shift obtained from magic-angle spinning. The number of dicarbonyl species can be quantitatively determined by the Carr- Purcell-Meiboom-Gill sequence, the powder pattern or by selective exchange experiments. At room temperature the two CO molecules in the gemdicarbonyl appear to undergo a mutual hopping exchange. This motion is frozen out at 198K. The carbon-carbon internuclear separation in the gemdicarbonyl is 3.3 Å.Catalysts pre-adsorbed with13CO undergo exchange of the dicarbonyl species upon exposure at 198 K to12CO, however they also react to form13CO2. When exposed to CO at room temperature no CO2formation is detected.

scholarly journals Cellulose of Salicornia brachiata

2010 ◽  
Vol 5 (4) ◽  
pp. 1934578X1000500 ◽  
Author(s):  
Naresh D Sanandiya ◽  
Kamalesh Prasad ◽  
Ramavatar Meena ◽  
Arup K Siddhanta
Keyword(s):  
Thermo Gravimetric Analysis ◽  
Magic Angle Spinning ◽  
Resonance Spectroscopy ◽  
Magic Angle ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
Salicornia Brachiata ◽  
Whatman Filter Paper ◽  
Angle Spinning ◽  
C Nmr

Cellulose was extracted from the roots, stems and stem tips of Salicornia brachiata Roxb. Each crude cellulose sample obtained was fractionated into α- and β-celluloses. The yields of crude cellulose from the stems and stem tips were greatest and lowest, respectively, while the yields of α- and β-celluloses were in the order, roots > stems > stem tips. The cellulose samples were characterized by Fourier transform infrared spectroscopy (FTIR), solid state cross polarisation magic angle spinning carbon-13 nuclear magnetic resonance spectroscopy (CP/MAS 13C NMR), X-ray diffraction pattern (XRD), thermo gravimetric analysis (TGA) and scanning electron microscopy (SEM). The data were compared with those of the celluloses (predominantly α-cellulose) isolated from Whatman filter paper No. 4 (WFP).

Further conventions for NMR shielding and chemical shifts (IUPAC Recommendations 2008)

2008 ◽  
Vol 80 (1) ◽  
pp. 59-84 ◽  
Author(s):  
Robin K. Harris ◽  
Edwin D. Becker ◽  
Sonia M. Cabral de Menezes ◽  
Pierre Granger ◽  
Roy E. Hoffman ◽  
...  
Keyword(s):  
High Resolution ◽  
Best Practice ◽  
Chemical Shifts ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Experimental Conditions ◽  
Effects Of Temperature ◽  
Angle Spinning ◽  
Universal Reference ◽  
C Nmr

IUPAC has published a number of recommendations regarding the reporting of nuclear magnetic resonance (NMR) data, especially chemical shifts. The most recent publication [Pure Appl. Chem.73, 1795 (2001)] recommended that tetramethylsilane (TMS) serve as a universal reference for reporting the shifts of all nuclides, but it deferred recommendations for several aspects of this subject. This document first examines the extent to which the 1H shielding in TMS itself is subject to change by variation in temperature, concentration, and solvent. On the basis of recently published results, it has been established that the shielding of TMS in solution [along with that of sodium-3-(trimethylsilyl)propanesulfonate, DSS, often used as a reference for aqueous solutions] varies only slightly with temperature but is subject to solvent perturbations of a few tenths of a parts per million (ppm). Recommendations are given for reporting chemical shifts under most routine experimental conditions and for quantifying effects of temperature and solvent variation, including the use of magnetic susceptibility corrections and of magic-angle spinning (MAS). This document provides the first IUPAC recommendations for referencing and reporting chemical shifts in solids, based on high-resolution MAS studies. Procedures are given for relating 13C NMR chemical shifts in solids to the scales used for high-resolution studies in the liquid phase. The notation and terminology used for describing chemical shift and shielding tensors in solids is reviewed in some detail, and recommendations are given for best practice.

scholarly journals Studies of Fluxionality in Pentachlorocyclopentadienylmercurials RHgC5Cl5 by Solution and Solid State 13C NMR and by 35Cl NQR Spectroscopy

1986 ◽  
Vol 41 (1-2) ◽  
pp. 175-178
Author(s):  
Gary Wulfsberg ◽  
A. C. Buchanan ◽  
Ira Rubin ◽  
Alarich Weiss ◽  
Daniel A. Davis ◽  
...  
Keyword(s):  
Solid State ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
35Cl Nqr ◽  
Angle Spinning ◽  
C Nmr ◽  
Solid State 13C Nmr

Solution and magic-angle-spinning solid-state 13C NMR spectra are reported for η1-(pentachlorocyclopentadienyl)( pentamethylphenyl) mercury, C6Me5HgC5Cl5 (II). The latter suggests that II is fluxional in the solid state. Some expected consequences of fluxional behavior also appear in the 35Cl NQR spectra of II and several related pentachlorocyclopentadienylmercurials.

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