scholarly journals Study of the Ability of Reducing Saccharides to Chemically Transform Lignin

2017 ◽  
Vol 19 (1) ◽  
pp. 31 ◽  
Author(s):  
O. Lepilova ◽  
G. Spigno ◽  
S.V. Aleeva ◽  
S.A. Koksharov
Keyword(s):  
Nucleophilic Addition ◽  
Plant Material ◽  
Galacturonic Acid ◽  
Uv Spectroscopy ◽  
Chemical Transformations ◽  
Peroxide Oxidation ◽  
Picea Excelsa ◽  
Lignin Reactivity ◽  
Hydrolysis Of ◽  
Differential Uv Spectroscopy

The efficiency of chemical transformations of lignin obtained from Picea excelsa wood under the action of galactose, galacturonic acid and xylose (which can be obtained by enzymatic hydrolysis of hemicelluloses and pectin containing in plant material) was evaluated. The results were compared with use of traditional reducing agent which was borohydride sodium. Using the method of differential UV-spectroscopy was confirmed the increase of a number of phenolic hydroxyl units by Xyl, Gal and GA. The increase of lignin reactivity was controlled to sulfuric acid and to peroxide hydrogen. Similarly to NaBH4, a nucleophilic addition mechanism for the reaction of the reducing saccharides with lignin was revealed. Reduction by NaBH4, Xyl, GA and Gal increased the lignin reactivity to acid solubilisation and to peroxide oxidation.

scholarly journals Preparation of Al/Fe-PILC clay catalysts from concentrated precursors: enhanced hydrolysis of pillaring metals and intercalation

RSC Advances ◽  
2020 ◽  
Vol 10 (66) ◽  
pp. 40450-40460
Author(s):  
Carlos Andrés Vallejo ◽  
Luis Alejandro Galeano ◽  
Raquel Trujillano ◽  
Miguel Ángel Vicente ◽  
Antonio Gil
Keyword(s):  
Solvent Free ◽  
Peroxide Oxidation ◽  
Highly Active ◽  
Wet Peroxide Oxidation ◽  
Catalytic Wet Peroxide Oxidation ◽  
Hydrolysis Of ◽  
Clay Catalysts

Significantly intensified preparation of Al/Fe-hydrolysed-pillaring solutions and solvent-free intercalation of bentonites yielding Al/Fe-PILCs highly active in catalytic wet peroxide oxidation.

Reaction Kinetics for the Hydrolysis of Titanium Isopropoxide Carboxylate Complexes

1992 ◽  
Vol 271 ◽  
Author(s):  
Charles D. Gagliardi ◽  
Dilum Dunuwila ◽  
Beatrice A. Van Vlierberge-Torgerson ◽  
Kris A. Berglund
Keyword(s):  
Carboxylic Acids ◽  
Ceramic Materials ◽  
Titanium Isopropoxide ◽  
General Interest ◽  
Chemical Transformations ◽  
Molecular Precursors ◽  
Novel Applications ◽  
Kinetics Of ◽  
Hydrolysis Of

ABSTRACTTitanium alkoxides modified by carboxylic acids have been widely studied as the molecular precursors to ceramic materials. These alkoxide complexes have also been very useful in the formation of stable, porous, optically clear films having many novel applications such as chemical sensors, catalytic supports, and ion-exchange media. To improve the processing of these materials, it is essential to better understand the kinetics of the chemical transformations which occur.The kinetics of the hydrolysis reaction are studied for selected carboxylic acids using Raman spectroscopy to probe the chemistry of the process. The study has a special emphasis on the titanium isopropoxide-valeric acid system due to the superior quality of these films over other carboxylates. Greater knowledge of the hydrolysis kinetics allows increased control over the quality of the film materials and should be of general interest to those working with modified metal alkoxides.

STRUCTURE OF A GALACTURONAN FROM SUNFLOWER PECTIC ACID

1966 ◽  
Vol 44 (11) ◽  
pp. 1275-1282 ◽  
Author(s):  
V. Zitko ◽  
C. T. Bishop
Keyword(s):  
Galacturonic Acid ◽  
Periodate Oxidation ◽  
Degree Of Polymerization ◽  
Critical Assessment ◽  
Molar Ratio ◽  
Aqueous Methanol ◽  
Pectic Acid ◽  
Potassium Borohydride ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

Fractions of sunflower pectic acid containing 89.8%, 94.2%, and 91.4% of D-galacturonic acid were carboxyl reduced as their methyl or ethylene glycol esters by potassium borohydride. Critical assessment of the effects of three different solvents (water, 80% aqueous dimethyl sulfoxide, and 80% aqueous methanol) on the efficiency of reduction showed that the latter solvent was best. The reductions caused a decrease in the degree of polymerization from 270 to 21. Measurement of the rates of hydrolysis of partially reduced pectic acids containing 90%, 41.6%, 19.9%, 11.0%, and 0.65% of D-galacturonic acid showed that the rate of hydrolysis was directly related to the proportion of galacturonosidic linkages present. Methylation and hydrolysis of the carboxyl-reduced pectic acid fractions yielded 2,3,4,6-tetra-O-methyl-D-galactose and 2,3,6-tri-O-methyl-D-galactose in an approximate molar ratio of 1:20. Results of the periodate oxidation of the carboxyl-reduced pectic acid supported the conclusion inferred from the methylation results that the pectic acid was a linear polymer of 1 → 4 linked α-D-galacturonic acid units.

ChemInform Abstract: Nucleophilic Addition to Olefins. Part 13. Kinetics of Hydrolysis of Benzylidene-1,3-indandione

1986 ◽  
Vol 17 (10) ◽  
Author(s):  
C. F. BERNASCONI ◽  
A. LAIBELMAN ◽  
J. L. ZITOMER
Keyword(s):  
Nucleophilic Addition ◽  
Kinetics Of Hydrolysis ◽  
Kinetics Of ◽  
Hydrolysis Of

Nucleophilic addition and subsequent oxime-assisted ester hydrolysis of diethyl .beta.-ketopropylphosphonate

1978 ◽  
Vol 43 (15) ◽  
pp. 3011-3015 ◽  
Author(s):  
Peter Livant ◽  
Michael Cocivera
Keyword(s):  
Nucleophilic Addition ◽  
Ester Hydrolysis ◽  
Hydrolysis Of

Hydrolysis of trioxaadamantane ortho esters. I. Dialkoxycarbocation – ortho ester equilibrium and acidity function

1984 ◽  
Vol 62 (6) ◽  
pp. 1068-1073 ◽  
Author(s):  
Robert A. McClelland ◽  
Patrick W. K. Lam
Keyword(s):  
Acid Concentration ◽  
Intramolecular Interaction ◽  
Uv Spectroscopy ◽  
Equilibrium Constants ◽  
Hydrolysis Product ◽  
Acidity Function ◽  
Ortho Ester ◽  
Aromatic Substituent ◽  
Ortho Esters ◽  
Hydrolysis Of

3-Aryl-2,4,10-trioxaadamantane ortho esters (T) undergo a rapid equilibration with a ring-opened dioxan-2-ylium ion (DH+) prior to hydrolysis to product (a 1,3,5-cyclohexanetriol monobenzoate). The cation is stable in concentrated H2SO4 solutions where it has been characterized by nmr spectroscopy. It is observed using uv spectroscopy in dilute acids, and the ratio [DH+]/[T] at equilibrium has been measured as a function of acidity. Reversibility of the ring opening is established by the pattern of plots of cation absorbance versus acid concentration and by the observation that solutions containing cation on neutralization or dilution yield ortho ester, not hydrolysis product. Equilibrium constants for the reaction [Formula: see text] have been measured by obtaining the acidity function HT for this system. The effects of the aromatic substituent and the steepness of the acidity function plot versus acid concentration are interpreted in terms of a strong intramolecular interaction in the cation between the cationic center and the hydroxyl oxygen.

Application of Differential UV Spectroscopy to the Determination of Lignin Substances in Polluted Water

2005 ◽  
Vol 60 (9) ◽  
pp. 833-837 ◽  
Author(s):  
P. A. Lozovik ◽  
A. E. Kaflyuk
Keyword(s):  
Uv Spectroscopy ◽  
Polluted Water ◽  
Differential Uv Spectroscopy
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