Studies on glucosammonium chloride. III. Kinetics of alkaline degradation in the centimolar concentration range

1959 ◽  
Vol 82 (2) ◽  
pp. 266-273 ◽  
Author(s):  
Howard K. Zimmerman
Keyword(s):  
Alkaline Degradation ◽  
Kinetics Of

The kinetics of the alkaline degradation of daptomycin

2001 ◽  
Vol 90 (8) ◽  
pp. 1066-1075 ◽  
Author(s):  
Walaisiri Muangsiri ◽  
Lee E. Kirsch
Keyword(s):  
Alkaline Degradation ◽  
Kinetics Of

Kinetics of the acid and alkaline degradation of oxytetracycline hydrochloride

1985 ◽  
Vol 85 ◽  
pp. 457-463 ◽  
Author(s):  
Nabila M. Guindy ◽  
S.A. Fattah ◽  
M.M. Amer
Keyword(s):  
Alkaline Degradation ◽  
Kinetics Of

Alkaline degradation of model compounds related to beech xylan

Holzforschung ◽  
2004 ◽  
Vol 58 (6) ◽  
pp. 588-596 ◽  
Author(s):  
Jürgen Sartori ◽  
Antje Potthast ◽  
Thomas Rosenau ◽  
Andreas Hofinger ◽  
Herbert Sixta ◽  
...  
Keyword(s):  
Capillary Electrophoresis ◽  
Industrial Production ◽  
Degradation Products ◽  
Isotopic Labeling ◽  
Alkaline Degradation ◽  
Chemical Behavior ◽  
Model Compounds ◽  
Degradation Reactions ◽  
Alkaline Conditions ◽  
Kinetics Of

Abstract To address the chemical behavior of beech xylan (O-acetyl-4-O-methyl-glucuronoxylan) under alkaline conditions, three model compounds, 2-O-methylxylobiose (1), aldobiouronic acid (4-O-methyl-α-D-glucopyranosyluronic acid-(1→2)-xylose, 2), and aldotriouronic acid (4-Omethyl-α-D-glucopyranosyluronic acid-(1→2)-β-D-xylopyranosyl-(1→4)-D-xylose, 3), were subjected to strong alkaline conditions equal to those used for the industrial production of viscose (18% NaOH, 43°C). Kinetics of the degradation of the model compounds were monitored by capillary electrophoresis in combination with pre-column derivatization. It was demonstrated that substitution at O-2 of the reducing xylose unit strongly retarded the alkaline degradation reactions (1 and 2). By isotopic labeling experiments and isolation of degradation products it was shown that under the pertinent conditions deprotonation at C-2 occurs, followed by epimerization to the respective lyxo derivative. Aldotriouronic acid 3 was degraded to 2 as an intermediate according to classical peeling pathways. Genuine degradation reactions and epimerization processes were distinguished.

Direct observations of radiation-enhanced transformations in glass

1983 ◽  
Vol 41 ◽  
pp. 354-355
Author(s):  
J. F. DeNatale ◽  
D. G. Howitt
Keyword(s):  
Glass Matrix ◽  
Diffusion Mechanism ◽  
Bubble Formation ◽  
Silicate Glasses ◽  
Phase Decomposition ◽  
Direct Observations ◽  
Thin Foils ◽  
Oxygen Bubble ◽  
Electron Energy Loss ◽  
Kinetics Of

The electron irradiation of silicate glasses containing metal cations produces various types of phase separation and decomposition which includes oxygen bubble formation at intermediate temperatures figure I. The kinetics of bubble formation are too rapid to be accounted for by oxygen diffusion but the behavior is consistent with a cation diffusion mechanism if the amount of oxygen in the bubble is not significantly different from that in the same volume of silicate glass. The formation of oxygen bubbles is often accompanied by precipitation of crystalline phases and/or amorphous phase decomposition in the regions between the bubbles and the detection of differences in oxygen concentration between the bubble and matrix by electron energy loss spectroscopy cannot be discerned (figure 2) even when the bubble occupies the majority of the foil depth.The oxygen bubbles are stable, even in the thin foils, months after irradiation and if van der Waals behavior of the interior gas is assumed an oxygen pressure of about 4000 atmospheres must be sustained for a 100 bubble if the surface tension with the glass matrix is to balance against it at intermediate temperatures.

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