scholarly journals Demethylation of Alkali Lignin with Halogen Acids and Its Application to Phenolic Resins

Polymers ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1771 ◽  
Author(s):  
Hao Wang ◽  
Thomas L. Eberhardt ◽  
Chunpeng Wang ◽  
Shishuai Gao ◽  
Hui Pan
Keyword(s):  
1H Nmr ◽  
Nucleophilic Reagent ◽  
2D Nmr ◽  
Hydroxyl Groups ◽  
Chemical Processing ◽  
Hydroxyl Content ◽  
Phenolic Resins ◽  
Alkali Lignin ◽  
Ft Ir ◽  
And Performance

Lignin, a byproduct from the chemical processing of lignocellulosic biomass, is a polyphenolic compound that has potential as a partial phenol substitute in phenolic adhesive formulations. In this study, HBr and HI were used as reagents to demethylate an alkali lignin (AL) to increase its hydroxyl content and thereby enhance its reactivity for the preparation of phenolic resins. Analyses by FT-IR, 1H-NMR and 2D-NMR(HSQC) demonstrated both a decrease in methoxyl groups and an increase in hydroxyl groups for each demethylated lignin (DL). In addition, the molar amounts of phenolic hydroxyls, determined by 1H-NMR, increased to 0.67 mmol/g for the HI-DL, and 0.64 mmol/g for the HBr-DL, from 0.52 mmol/g for the AL. These results showed that HI, a stronger nucleophilic reagent than HBr, provided a higher degree of AL demethylation. Lignin-containing resins, prepared by copolymerization, met the bonding strength standard for exterior plywood with DL used to replace as much as 50 wt.% of phenol. The increased hydroxyl contents resulting from the lignin demethylations also imparted faster cure times for the lignin-containing resins and lower formaldehyde emissions. Altogether, the stronger nucleophilicity of HI, compared to HBr, impacted the degree of lignin demethylation, and carried through to measurable differences the thermal properties and performance of the lignin-containing PF resins.

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.

Synthesis of Polyfunctional Castor Oil-Based Polyurethane Acrylate by the Auxiliary of Thiol-Ene Click Reaction

2015 ◽  
Vol 731 ◽  
pp. 553-557
Author(s):  
Xiao Yuan Guan ◽  
Guang Xue Chen ◽  
Ming Hui He
Keyword(s):  
Thermal Stability ◽  
Castor Oil ◽  
Addition Reaction ◽  
Click Reaction ◽  
Molar Ratio ◽  
Hydroxyl Content ◽  
Polyhydroxy Compounds ◽  
Polyurethane Acrylate ◽  
Ft Ir ◽  
And Performance

In this paper, we report a synthetic method to prepare vegetable oil-based polyurethane acrylate (PUA) resin, which can be used in photo polymerization coating, ink and other fields. First, the mercaptoethanol was introduced into castor oil via thiol-ene photo-click reaction with UV irradiation, forming polyhydroxy compounds, then we added the isocyanate acrylate, which was obtained by the reaction between hydroxypropyl acrylate (HPA) and isophorone diisocyanate (IPDI), into polyhydroxy compounds, the molar ratio of HPA and IPDI is 1:1. Finally, we get the castor oil-based polyurethane acrylate. Different functional acrylate can be obtained by adjusting the hydroxyl content. Furthermore, the structure and performance of Polyurethane acrylate was confirmed by FT-IR and TG. The water absorption and adhesion of synthetic polyurethane acrylate were tested. Meanwhile, the thermal stability was studied. The results indicated that the thiol-ene addition reaction was proceeded and compared to our previous studies, the properties of cured film are greatly improved, especially the hardness and thermal stability.

scholarly journals Isolation of terpenoid compound of n-hexane extract of Marsilea crenata Presl..

2020 ◽  
Vol 4 (2) ◽  
Author(s):  
Burhan Ma'arif ◽  
Mangestuti Agil ◽  
Retno Widyowati
Keyword(s):  
1H Nmr ◽  
Column Chromatography ◽  
13C Nmr ◽  
Structure Elucidation ◽  
2D Nmr ◽  
Hexane Extract ◽  
Pentacyclic Triterpenoid ◽  
Vacuum Column ◽  
Ft Ir

Isolation, identification, and structure elucidation of terpenoid compounds from an n-hexane extract of Marsilea crenata Presl., had been done. The leaves of M. crenata was extracted using n-hexane solvent. The extract then separated with vacuum column chromatography and open column chromatography to obtain the isolate. Furthermore, the isolate was identified and elucidated using UV-Vis, FT-IR, 1H-NMR, 13C- NMR, and 2D-NMR (COSY, HMQC, and HMBC). The identification and elucidation of the isolated structure from an n-hexane extract of M. crenata leaves indicate the isolate was a pentacyclic triterpenoid. 

Study on Mechanism of Action of Catalysts on Liquefaction of Bagasse Alkali Lignin

2011 ◽  
Vol 383-390 ◽  
pp. 6145-6150 ◽  
Author(s):  
Xin Jin Sui ◽  
Shu Bin Wu
Keyword(s):  
Mechanism Of Action ◽  
Black Liquor ◽  
Total Yield ◽  
Structural Rearrangement ◽  
Hydroxyl Groups ◽  
Use Value ◽  
Optimal Conditions ◽  
Alkali Lignin ◽  
H Nmr ◽  
Ft Ir

Bagasse alkali lignin is the primary constituent of pulping black liquor. The phenolic products such as phenol, 2,6-dimethoxy-phenol and 2-methoxy-phenol were obtained by catalytic liquefaction from bagasse alkali lignin, with the aim of enhancing its use value. In the investigation, under optimal conditions, using SiO2-Al2O3 or FeS as catalyst, the phenols yield reached 54.10% and 55.18%, respectively. HPLC spectrum showed that the phenolic products of them were different. FT-IR and H-NMR spectrums showed that, using SiO2-Al2O3 as the catalyst, the α-O-4 and β-O-4 ether bonds and C-Cα bonds of lignin units were prone to break, forming 2,6-dimethoxy-phenol, 2-methoxy-phenol and phenol. While FeS action was more difficult, the α-O-4 and β-O-4 ether bonds and Cα-Cβ bonds of lignin units broke down. Then, the introduction of additional hydroxyl groups from glycols consequently increased the final product solubility. At the same time, Cα–C bond of the phenylpropane linkage was broken to produce phenolic chemicals. Third, part of the phenylpropane linkage was prone to break Cα–Cβ bond and structural rearrangement occurred. So the content of 2-methoxy-4-methyl-phenol and the total yield of phenols were high.

1H NMR Relaxometry and ATR-FT-IR Spectrosopy Used for the Assesment of Wastewater Treatment in Slaughterhouse

2018 ◽  
Vol 63 (1-2) ◽  
pp. 49-60
Author(s):  
R. Crainic ◽  
◽  
L. R. Drăgan ◽  
R. Fechete ◽  
◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
1H Nmr ◽  
Nmr Relaxometry ◽  
Ft Ir ◽  
1H Nmr Relaxometry

119Sn, 13C and 1H NMR Spectra of Tris(1-butyl)stannyl D-Glucuronate

1997 ◽  
Vol 62 (8) ◽  
pp. 1169-1176 ◽  
Author(s):  
Antonín Lyčka ◽  
Jaroslav Holeček ◽  
David Micák
Keyword(s):  
Chemical Shift ◽  
Carbonyl Group ◽  
1H Nmr ◽  
Equatorial Plane ◽  
Title Compound ◽  
Nmr Spectra ◽  
Hydroxyl Groups ◽  
Carboxylic Group ◽  
H Nmr ◽  
Oxygen Atoms

The 119Sn, 13C and 1H NMR spectra of tris(1-butyl)stannyl D-glucuronate have been measured in hexadeuteriodimethyl sulfoxide, tetradeuteriomethanol and deuteriochloroform. The chemical shift values have been assigned unambiguously with the help of H,H-COSY, TOCSY, H,C-COSY and 1H-13C HMQC-RELAY. From the analysis of parameters of 119Sn, 13C and 1H NMR spectra of the title compound and their comparison with the corresponding spectra of tris(1-butyl)stannyl acetate and other carboxylates it follows that in solutions of non-coordinating solvents (deuteriochloroform) the title compound is present in the form of more or less isolated individual molecules with pseudotetrahedral environment around the central tin atom and with monodentately bound carboxylic group. The interaction of tin atom with oxygen atoms of carbonyl group and hydroxyl groups of the saccharide residue - if they are present at all - are very weak. In solutions in coordinating solvents (hexadeuteriodimethyl sulfoxide or tetradeuteriomethanol), the title compound forms complexes with one molecule of the solvent. Particles of these complexes have a shape of trigonal bipyramid with the 1-butyl substituents in equatorial plane and the oxygen atoms of monodentate carboxylic group and coordinating solvent in axial positions.

scholarly journals Synthesis, Fabrication, and Characterization of Functionalized Polydiacetylene Containing Cellulose Nanofibrous Composites for Colorimetric Sensing of Organophosphate Compounds

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1869
Author(s):  
A K M Mashud Alam ◽  
Donovan Jenks ◽  
George A. Kraus ◽  
Chunhui Xiang
Keyword(s):  
Solid State ◽  
Hydroxyl Groups ◽  
Colorimetric Sensing ◽  
Electrospinning Technique ◽  
Hazardous Chemical ◽  
Tensile Tester ◽  
Vis Spectroscopy ◽  
Ft Ir ◽  
Landmark Study

Organophosphate (OP) compounds, a family of highly hazardous chemical compounds included in nerve agents and pesticides, have been linked to more than 250,000 annual deaths connected to various chronic diseases. However, a solid-state sensing system that is able to be integrated into a clothing system is rare in the literature. This study aims to develop a nanofiber-based solid-state polymeric material as a soft sensor to detect OP compounds present in the environment. Esters of polydiacetylene were synthesized and incorporated into a cellulose acetate nanocomposite fibrous assembly developed with an electrospinning technique, which was then hydrolyzed to generate more hydroxyl groups for OP binding. Scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), Instron® tensile tester, contact angle analyzer, and UV–Vis spectroscopy were employed for characterizations. Upon hydrolysis, polydiacetylene esters in the cellulosic fiber matrix were found unaffected by hydrolysis treatment, which made the composites suitable for OP sensing. Furthermore, the nanofibrous (NF) composites exhibited tensile properties suitable to be used as a textile material. Finally, the NF composites exhibited colorimetric sensing of OP, which is visible to the naked eye. This research is a landmark study toward the development of OP sensing in a protective clothing system.

scholarly journals 5-((8-Hydroxyquinolin-5-yl)diazenyl)-3-methyl-1H-pyrazole-4-carboxylic Acid

Molbank ◽  
10.3390/m1238 ◽  
2021 ◽  
Vol 2021 (2) ◽  
pp. M1238
Author(s):  
Ion Burcă ◽  
Valentin Badea ◽  
Calin Deleanu ◽  
Vasile-Nicolae Bercean
Keyword(s):  
Chemical Structure ◽  
Functional Group ◽  
Coupling Reaction ◽  
2D Nmr ◽  
Azo Coupling ◽  
2D Nmr Spectroscopy ◽  
Azo Compound ◽  
Ft Ir ◽  
New Compounds ◽  
Carboxylic Functional Group

A new azo compound was prepared via the azo coupling reaction between 4-(ethoxycarbonyl)-3-methyl-1H-pyrazole-5-diazonium chloride and 8-hydroxyquinoline (oxine). The ester functional group of the obtained compound was hydrolyzed and thus a new chemical structure with a carboxylic functional group resulted. The structures of the new compounds were fully characterized by: UV–Vis, FT-IR, 1D and 2D NMR spectroscopy, and HRMS spectrometry.

Bimetallic Group 6 Tricarbonyls Triply-Bridged by Bis(phenylthio)alkane Bidentate Ligands

2010 ◽  
Vol 93-94 ◽  
pp. 13-16
Author(s):  
Khalil J. Asali
Keyword(s):  
1H Nmr ◽  
Elemental Analysis ◽  
Thermodynamic Stability ◽  
Chlorinated Hydrocarbons ◽  
Metal Center ◽  
Molar Ratio ◽  
Bidentate Ligands ◽  
Group 6 ◽  
Ft Ir

Reactions of the labile complex (Me3tach)M(CO)3 (Me3tach = 1,3,5-trimethyl-1,3,5-triazacyclohexane; M = W, Mo) with bis(phenylthio)alkanes ( = PhS(CH2)nSPh), (2:3 molar ratio) in CH2Cl2 as solvent (at 35 oC M = W, 0 oC M = Mo) afforded in good yields bimetallic tricarbonyl complexes triply- bridged by bis(phenylthio)alkanes of the type [M(CO)3]2(μ-PhS-(CH2)n-SPh)3 [n = 3 (a), 4 (b), 5 (c), 6 (d); M = W (1), Mo (2)]. These new triply-bridged complexes were characterized by 1H NMR, FT-IR and elemental analysis. Additionally, it has been observed that the thermodynamic stability of some of these new complexes in chlorinated hydrocarbons depends mainly on the nature of the metal center and varies in the order W >> Mo.

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