A novel simple route to wood acetylation by transesterification with vinyl acetate

Holzforschung ◽  
2007 ◽  
Vol 61 (2) ◽  
pp. 143-147 ◽  
Author(s):  
Mohamed Jebrane ◽  
Gilles Sèbe
Keyword(s):  
Vinyl Acetate ◽  
Classical Method ◽  
Transesterification Reaction ◽  
High Yield ◽  
Hydroxyl Groups ◽  
Weight Percentage ◽  
Novel Method ◽  
Increasing Temperature ◽  
Cp Mas Nmr ◽  
Weight Percentage Gain

Abstract A novel method for the acetylation of wood was investigated and compared with the classical method based on acetic anhydride. The transesterification reaction between vinyl acetate (VA) and hydroxyl groups of maritime pine sapwood (Pinus pinaster Soland) was performed in the presence of potassium carbonate as a catalyst and led to acetylated wood in high yield. The transesterification reaction was confirmed by FTIR and 13C CP-MAS NMR spectroscopy. The efficiency of the VA transesterification increased with increasing temperature, reaction time, and catalyst amount, but a significant weight percentage gain (WPG) was obtained after only 3 h at 90°C.

Covalent fixation of boron in wood through transesterification with vinyl ester of carboxyphenylboronic acid

Holzforschung ◽  
2016 ◽  
Vol 70 (6) ◽  
pp. 577-583 ◽  
Author(s):  
Mohamed Jebrane ◽  
Ivo Heinmaa
Keyword(s):  
Reaction Time ◽  
Nmr Spectroscopy ◽  
Vinyl Ester ◽  
Hydroxyl Groups ◽  
Weight Percentage ◽  
Permanent Fixation ◽  
Increasing Temperature ◽  
Cp Mas Nmr ◽  
Weight Percentage Gain ◽  
C Nmr

Abstract Vinyl ester of 4-carboxyphenylboronic acid has been synthesized and tested as reactive reagent for permanent fixation of boron in wood based on an improved approach described previously. The essence of the method is a covalent incorporation of the boron compound via transesterification between wood hydroxyl groups and vinyl ester containing boron. The synthesis of this vinyl ester was accomplished by exchange reaction of vinyl acetate with 4-carboxyphenylboronic acid. The obtained vinyl ester of carboxyphenylboronic acid was characterized by FTIR and 1H-, and 13C-NMR spectroscopy. The covalent fixation of boron to wood’s hydroxyl groups was achieved through potassium carbonate (K2CO3) catalyzed transesterification of the vinyl ester containing boron. The transesterification was confirmed by weight percentage gain (WPG) calculation, curcumin staining, FTIR, and 13C CP-MAS NMR spectroscopy. The efficiency of the reaction improved with increasing temperature and reaction time.

Influence Analysis of Sampling Time for Synthesis of Carbon Nanotubes in the V-Type Pyrolysis Flame

2011 ◽  
Vol 221 ◽  
pp. 235-239 ◽  
Author(s):  
Yuan Chao Liu ◽  
Bao Min Sun ◽  
Zhao Yong Ding
Keyword(s):  
Carbon Nanotubes ◽  
Electron Microscope ◽  
Experimental System ◽  
Growth Period ◽  
Sampling Time ◽  
High Yield ◽  
Spray Pyrolysis Method ◽  
Transmission Electron ◽  
Novel Method ◽  
Synthesis Of Carbon Nanotubes

Synthesis of carbon nanotubes from V-type pyrolysis flame is a kind of novel method. It needs simple laboratory equipments and normal atmosphere pressure. The V-type pyrolysis flame experimental system is introduced. Carbon source is the carbon monoxide and heat source is from acetylene/air premixed flame. Pentacarbonyl iron, served as catalyst, is transported by spray- pyrolysis method into the flame. The carbon nanotubes were characterized by scanning electron microscope and transmission electron microscope. This study aims to find the formation rule of carbon nanotubes from the V-type pyrolysis flame in different sampling times. The carbon nanotubes with less impurity and high yield were captured successfully in the V-type pyrolysis flame. The diameter of carbon nanotubes was approximate between 10nm and 20nm, and its length was dozens of microns. When the sampling time was below 3 minutes, the growth of carbon nanotubes came into the preparation growth period. The length of the carbon nanotubes increased gradually and the diameter had no obvious change with the extension of sampling time. When the sampling time was continued to the 5th minute, the growth of carbon nanotubes came into the exuberant growth period. The carbon nanotubes growth was finished within 5minutes. Longer sampling time was meaningless after the carbon nanotubes formation.

Enhanced Thermal Stability of Esterified Lignin in Different Solvent Mediums

2018 ◽  
Vol 9 (1) ◽  
pp. 39-49 ◽  
Author(s):  
Sharifah Nurul Ain Syed Hashim ◽  
Sarani Zakaria ◽  
Chin Hua Chia ◽  
Sharifah Nabihah Syed Jaafar
Keyword(s):  
Thermal Stability ◽  
Alkaline Solution ◽  
Room Temperature ◽  
Hydroxyl Groups ◽  
Aqueous Alkaline Solution ◽  
Alkali Lignin ◽  
Weight Percentage ◽  
H Nmr ◽  
Ft Ir ◽  
Thermal Stability Of

In this study, soda alkali lignin from oil palm empty fruit bunch (EFB-AL) and kenaf core (KC-AL) are esterified with maleic anhydride under two different conditions, namely i) pyridine at temperature of 120°C for 3h and ii) aqueous alkaline solution at room temperature for 4h. As a result, the weight percentage gain (WPG) of the esterified EFB-AL (EFB-EL) and esterified KC-AL (KC-EL) in pyridine demonstrated a higher compared to aqueous alkaline solution. The FT-IR results of EFB-EL and KC-EL in both solvents exhibited some changes at the carbonyl and hydroxyl groups. Furthermore, the esterification process induced the carboxylic peak to appear in both alkali lignin samples. The outcome is confirmed by conducting H-NMR analysis, which demonstrated ester and carboxylic acid peaks within the spectral analysis. Finally, the TGA results showed both EFB-EL and KC-EL that are exposed to aqueous alkaline actually possessed better thermal stability and higher activation energy (Ea) compared to the esterified samples in pyridine.

scholarly journals A Novel Inulin-Mediated Ethanol Precipitation Method for Separating Endo-Inulinase From Inulinases for Inulooligosaccharides Production From Inulin

2021 ◽  
Vol 9 ◽  
Author(s):  
Xin Li ◽  
Qiannan Zhang ◽  
Wei Wang ◽  
Shang-Tian Yang
Keyword(s):  
Enzymatic Hydrolysis ◽  
Aspergillus Niger ◽  
Functional Food ◽  
Degree Of Polymerization ◽  
Precipitation Method ◽  
High Yield ◽  
Process Conditions ◽  
Food Ingredients ◽  
Ethanol Precipitation ◽  
Novel Method

Inulin is a kind of polysaccharide that can be obtained various biomass. Inulooligosaccharides (IOS), a kind of oligosaccharides that can be obtained from inulin by enzymatic hydrolysis using inulinases, have been regarded as the functional food ingredients. Commercially available inulinases produced by natural Aspergillus niger contained both endo- and exo-inulinase activities. For IOS production from inulin, it is desirable to use only endo-inulinase as exo-inulinase would produce mainly the monosacchairde fructose from inulin. In the present study, a simple inulin-mediated ethanol precipitation method was developed to separate endo- and exo-inulinases present in natural inulinases. IOS production from inulin using the enriched endo-inulinase was then optimized in process conditions including pH and temperature, achieving a high yield of ∼94%. The resultant IOS products had a degree of polymerization ranging from 2 to 7. The study demonstrated a novel method for obtaining partially purified or enriched endo-inulinase for IOS production from inulin in an efficient process.

scholarly journals The potential of magnetisation transfer NMR to monitor the dissolution process of cellulose in cold alkali

Cellulose ◽  
2019 ◽  
Vol 26 (18) ◽  
pp. 9403-9412 ◽  
Author(s):  
Maria Gunnarsson ◽  
Merima Hasani ◽  
Diana Bernin
Keyword(s):  
Hydrophobic Interactions ◽  
Dissolution Process ◽  
Mechanistic Study ◽  
Dissolution Mechanism ◽  
Hydroxyl Groups ◽  
Similar Amount ◽  
Magnetisation Transfer ◽  
Promising Alternative ◽  
Nmr Methods ◽  
Increasing Temperature

Abstract Cellulose is the most important biopolymer on earth and, when derived from e.g. wood, a promising alternative to for example cotton, which exhibits a large environmental burden. The replacement depends, however, on an efficient dissolution process of cellulose. Cold aqueous alkali systems are attractive but these solvents have peculiarities, which might be overcome by understanding the acting mechanisms. Proposed dissolution mechanisms are for example the breakage of hydrophobic interactions and partly deprotonation of the cellulose hydroxyl groups. Here, we performed a mechanistic study using equimolar aqueous solutions of LiOH, NaOH and KOH to elucidate the dissolution process of microcrystalline cellulose (MCC). The pH was the highest for KOH(aq) followed by NaOH(aq) and LiOH(aq). We used a combination of conventional and advanced solution-state NMR methods to monitor the dissolution process of MCC by solely increasing the temperature from − 10 to 5 °C. KOH(aq) dissolved roughly 25% of the maximum amount of MCC while NaOH(aq) and LiOH(aq) dissolved up to 70%. Water motions on nanoscale timescales present in non-frozen water, remained unaffected on the addition of MCC. Magnetisation transfer (MT) NMR experiments monitored the semi-rigid MCC as a function of temperature. Interestingly, although NaOH(aq) and LiOH(aq) were able to dissolve a similar amount at 5 °C, MT spectra revealed differences with increasing temperature, suggesting a difference in the swollen state of MCC in LiOH(aq) already at − 10 °C. Furthermore, MT NMR shows a great potential to study the water exchange dynamics with the swollen and semi-rigid MCC fraction in these systems, which might give valuable insights into the dissolution mechanism in cold alkali.

Online determination of chemical and physical properties of poly(ethylene vinyl acetate) pellets using a novel method of near-infrared spectroscopy combined with angle transformation

2019 ◽  
Vol 11 (18) ◽  
pp. 2435-2442 ◽  
Author(s):  
Jinchun Xie ◽  
Hongfu Yuan ◽  
Chunfeng Song ◽  
Xiangjun Yan ◽  
Hao Yan ◽  
...  
Keyword(s):  
Quality Control ◽  
Infrared Spectroscopy ◽  
Vinyl Acetate ◽  
Near Infrared ◽  
Ethylene Vinyl Acetate ◽  
Melt Flow Rate ◽  
Production Processes ◽  
Novel Method ◽  
Poly Ethylene

Melt flow rate (MFR) and vinyl acetate content (VAC) are the target parameters for quality control of poly(ethylene vinyl acetate) (EVA) pellets in production processes.

XRD, FTIR and 13C CP/MAS NMR Studies of Composite Comprising Poly(vinyl acetate)-Silylated Si-MCM-41

2011 ◽  
Vol 364 ◽  
pp. 159-163
Author(s):  
Izza Taib Nurul ◽  
Salasiah Endud ◽  
M. Nasir Katun
Keyword(s):  
Carbonyl Group ◽  
Vinyl Acetate ◽  
Silica Matrix ◽  
Mas Nmr ◽  
Polymer Chains ◽  
Confined Space ◽  
Nmr Studies ◽  
Solution Intercalation ◽  
Cp Mas Nmr ◽  
Mcm 41

A composite structure based on silylated MCM-41 and Poly (vinyl acetate) (PVAc) was synthesized via solution intercalation. Poly (vinyl acetate)-silylated Si-MCM-41 composite were characterized by XRD, FTIR spectroscopy and13C CP/MAS NMR in order to determine the compatibility between PVAc and the silicate host. XRD study reveals that the framework of silylated Si-MCM-41 was not altered upon incorporation of PVAc. FTIR study showed that characteristic peak assigned to carbonyl group in PVAc was observed around 1741.6 cm-1for all the composites indicating the presence of PVAc in the silylated Si-MCM-41.13C CP/MAS NMR showed the increase of line width of the peak assigned to C=O carbonyl group indicating the increase in randomness of polymer chains in confined space. The shifting of the C=O carbonyl groups is a sign of the change in chemical environment of the carbonyl owing to the interaction of PVAc with the silica matrix of silylated Si-MCM-41.

The effect of hydrogen on the formation of carbon nanotubes and fullerenes

1995 ◽  
Vol 10 (8) ◽  
pp. 1977-1983 ◽  
Author(s):  
X.K. Wang ◽  
X.W. Lin ◽  
M. Mesleh ◽  
M.F. Jarrold ◽  
V.P. Dravid ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Carbon Nanotubes ◽  
Growth Model ◽  
Arc Discharge ◽  
Time Of Flight ◽  
Gas Pressure ◽  
High Yield ◽  
Nanotube Bundles ◽  
Flight Mass Spectrometry ◽  
Novel Method

A novel method to synthesize “clean” carbon nanotubes with relatively high yield in a hydrogen arc discharge has been developed. The quality and yield of the tubes depend sensitively on the gas pressure in the arc discharge. Sharp, open-ended nanotubes with clear lattice fringes at the edges and empty interiors have been observed. The existence of these frozen-open-ended tubes as part of nanotube-bundles provides evidence for an open-ended growth model for nanotubes. Using time of flight mass spectrometry, it was found that fullerenes, such as C60 and C70, are almost absent from the soot collected in the hydrogen arc discharge. The effect of hydrogen on the formation of fullerenes, both in the laboratory and in space, will be discussed.

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