Electrochemical Investigations of Alkaline Cleavage of Lignin Under Mild Conditions

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Title:Electrochemical Investigations of Alkaline Cleavage of Lignin Under Mild Conditions
Creators:
Zuman, Petr
Rupp, Elinore B.
Journal or Publication Title:
Collection of Czechoslovak Chemical Communications, 66, 7, pp. 1125-1139
Uncontrolled Keywords:Phenols, Lignans, Hydroxybenzaldehydes, Polarography, Hydrolysis, Aldehydes, Lignins

Abstract

At pH 8-12 and 25 °C, 10-20% of lignin undergoes cleavage producing soluble species. In suspensions of lignin it is possible to follow the concentration changes of hydroxybenzaldehydes and α,β-unsaturated carbonyl compounds. These species can be determined by the recording of polarographic current-voltage curves directly in the suspensions, where the presence of suspended and colloidal particles does not interfere with the function of the DME. The base-catalyzed cleavage follows first-order kinetics. The pH dependence indicates that the rate determining step is not a nucleophilic attack by OH<sup>-</sup>, rather the rate determining step is preceded by a rapidly established acid-base equilibrium. The cleavage of natural lignins obtained enzymatically follows a pattern similar to that of rot wood lignins and surprisingly also to that of kraft lignins. The patterns of cleavages are different from those of lignosulfonates, Klason, periodate and expansion lignin. The three dimensional (tertiary) structure of lignin seems to play a role in its reactivity. <p>

Title:Electrochemical Investigations of Alkaline Cleavage of Lignin Under Mild Conditions
Creators:
Zuman, Petr
Rupp, Elinore B.
Uncontrolled Keywords:Phenols, Lignans, Hydroxybenzaldehydes, Polarography, Hydrolysis, Aldehydes, Lignins
Divisions:Life and Chemical Sciences > Institute of Organic Chemistry and Biochemistry > Collection of Czechoslovak Chemical Communications
Journal or Publication Title:Collection of Czechoslovak Chemical Communications
Volume:66
Number:7
Page Range:pp. 1125-1139
ISSN:0010-0765
E-ISSN:1212-6950
Publisher:Institute of Organic Chemistry and Biochemistry
Related URLs:
URLURL Type
http://dx.doi.org/10.1135/cccc20011125UNSPECIFIED
ID Code:1846
Item Type:Article
Deposited On:06 Feb 2009 17:13
Last Modified:06 Feb 2009 16:13

Citation

Zuman, Petr; Rupp, Elinore B. (2001) Electrochemical Investigations of Alkaline Cleavage of Lignin Under Mild Conditions. Collection of Czechoslovak Chemical Communications, 66 (7). pp. 1125-1139. ISSN 0010-0765

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