Spectrophotometric, potentiometric and chromatographic pKa values of polyphenolic acids in water and acetonitrile–water media

2003 ◽  
Vol 484 (2) ◽  
pp. 253-264 ◽  
Author(s):  
J.L. Beltrán ◽  
N. Sanli ◽  
G. Fonrodona ◽  
D. Barrón ◽  
G. Özkan ◽  
...  
Keyword(s):  
Pka Values ◽  
Water Media ◽  
Polyphenolic Acids

Prediction of Alkanolamine pKa Values by Combined Molecular Dynamics Free Energy Simulations and ab initio Calculations

2019 ◽  
Author(s):  
Javad Noroozi ◽  
William Smith
Keyword(s):  
Molecular Dynamics ◽  
Free Energy ◽  
Ab Initio Calculations ◽  
Gas Phase ◽  
Quantum Chemical ◽  
Phase Reaction ◽  
Pka Values ◽  
Gas Phase Reaction ◽  
Reaction Free Energy ◽  
Energy Simulations

We use molecular dynamics free energy simulations in conjunction with quantum chemical calculations of gas phase reaction free energy to predict alkanolamines pka values. <br>

Use of artificial wetland for the treatment of surface and wastewater

1996 ◽  
Vol 33 (4-5) ◽  
pp. 309-313
Author(s):  
Jan Šálek ◽  
František Marcián ◽  
Iman Elazizy
Keyword(s):  
Water Level ◽  
Root Zone ◽  
Artificial Wetland ◽  
Root Zones ◽  
Different Types ◽  
Water Media ◽  
Inlet Zone

Vegetative root zone methods are based on self-purifying processes that take place in the soil, wetland and vegetation containing water media. Our studies are concentrated on the course of puryfying in relation with the length of the filtration bed and on the progress of eliminating the ammoniacal pollution. The research proved that the essential part of the puryfying process takes place within the inlet zone (Figs 1 and 2). The decomposition of ammonia proceeds very slowly. The process of nitrification is affected by the lack of oxygen in the filtration media. To improve the effectiveness of vegetative root zone methods we suggest specific steps: an adjustment of the inlet zone, a system of cascades, a water level pulsation system and combinations of different types and arrangements of vegetative root zones.

Carboxylic acid-catalysed hydrolysis of rhamnogalacturonan in subcritical water media

2021 ◽  
pp. 105268
Author(s):  
Carla S. Valdivieso Ramirez ◽  
Feral Temelli ◽  
Marleny D.A. Saldaña
Keyword(s):  
Carboxylic Acid ◽  
Subcritical Water ◽  
Water Media ◽  
Hydrolysis Of

Carboxylic acid-catalysed hydrolysis of polygalacturonic acid in subcritical water media

2020 ◽  
pp. 105103
Author(s):  
Carla S. Valdivieso Ramirez ◽  
Jose E. Sanchez Gallego ◽  
Michael Gänzle ◽  
Feral Temelli ◽  
Marleny D.A. Saldaña
Keyword(s):  
Carboxylic Acid ◽  
Subcritical Water ◽  
Polygalacturonic Acid ◽  
Water Media ◽  
Hydrolysis Of

scholarly journals Kinetics and Mechanism of the Change of the 4-Nitrobenzylthio-System into 4,4′-Diformylazoxybenzene in Alkaline Dioxane-Water Media

1985 ◽  
Vol 40 (11) ◽  
pp. 1128-1132
Author(s):  
Y. Riad ◽  
Adel N. Asaad ◽  
G.-A. S. Gohar ◽  
A. A. Abdallah
Keyword(s):  
Acetic Acid ◽  
Sodium Hydroxide ◽  
Rate Constants ◽  
Main Product ◽  
Reaction Medium ◽  
Aqueous Dioxane ◽  
Proton Abstraction ◽  
First Order ◽  
Water Media ◽  
Different Temperatures

Sodium hydroxide reacts with α -(4-nitrobenzylthio)-acetic acid in aqueous-dioxane media to give 4,4'-diformylazoxybenzene as the main product besides 4,4'-dicarboxyazoxybenzene and a nitrone acid. This reaction was kinetically studied in presence of excess of alkali in different dioxane-water media at different temperatures. It started by a fast reversible a-proton abstraction step followed by two consecutive irreversible first-order steps forming two intermediates (α -hydroxy, 4-nitrosobenzylthio)-acetic acid and 4-nitrosobenzaldehyde. The latter underwent a Cannizzaro's reaction, the products of which changed in the reaction medium into 4,4'-diformylazoxybenzene and 4,4'-dicarboxyazoxybenzene. The rate constants and the thermodynamic parameters of the two consecutive steps were calculated and discussed. A mechanism was put forward for the formation of the nitrone acid.Other six 4-nitrobenzyl, aryl sulphides were qualitatively studied and they gave mainly 4,4'-diformylazoxybenzene beside 4,4'-dicarboxyazoxybenzene or its corresponding azo acid.

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