Pulse polarographic study of the behaviour of some o,o'-dihydroxyazo-compounds

1989 ◽  
Vol 54 (5) ◽  
pp. 1219-1226 ◽  
Author(s):  
Enric Casassas ◽  
Miquel Esteban ◽  
Santiago Alier
Keyword(s):  
Carboxylic Acid ◽  
Reaction Mechanisms ◽  
Sulphonic Acid ◽  
Base Catalysis ◽  
Polarographic Study ◽  
Acid Base ◽  
Eriochrome Black T ◽  
Naphthoic Acid ◽  
Calcon Carboxylic Acid

The reduction of several o,o'-dihydroxyazo-compounds is studied by means of pulse polarographic techniques (DPP, NPP and RPP). The compounds studied are the following: 2-(2'-hydroxyphenylazo)-phenol (o,o'-dihydroxyazobenzene), 1-(2'-hydroxy-1'-naphthylazo)-2-naphthol-4-sulphonic acid (calcon or Eriochrome Blue Black R), 1-(2'-hydroxy-4'-sulpho-1'-naphthylazo)-2-hydroxy-3-naphthoic acid (calcon carboxylic acid), and 1-(1'-hydroxy-2'-naphthylazo)-6-nitro-2-naphthol-4-sulphonic acid (Eriochrome Black T). Correlations between Ip and Epand experimental variables (pH, T, conc.) and instrumental parameters (dropping time, t, and pulse magnitude, ΔE) are established. Reaction mechanisms formerly proposed are discussed on the basis of the new obtained results, and the ranges are defined where adsorption and/or acid-base catalysis are operative.

Kinetics of the dehydration of methylene glycol in aqueous solution

1966 ◽  
Vol 291 (1426) ◽  
pp. 297-323 ◽  
Keyword(s):  
Aqueous Solution ◽  
Reaction Mechanisms ◽  
Base Catalysis ◽  
Acid Base ◽  
Wide Range ◽  
Base Strength ◽  
Catalytic Behaviour ◽  
Rapid Reaction ◽  
Kinetics Of ◽  
Catalytic Power

Methods are described for measuring the velocity of the reaction CH 2 (OH) 2 → CH 2 O+H 2 O in aqueous solution by making use of the rapid reaction of unhydrated formaldehyde with the scavenging reagents semicarbazide, hydroxylamine, phenylhydrazine, hydrazine and sulphite. The reaction exhibits general acid-base catalysis, and catalytic constants are given for 14 acids and 30 bases. Relations between acid-base strength and catalytic power extend over an unusually wide range of velocities and types of catalyst, and this behaviour is discussed in terms of reaction mechanisms. The catalytic behaviour observed shows unexpected contrasts with that reported for the hydration of carbon dioxide. It is shown that, contrary to previous reports, the rate of removal of formaldehyde from aqueous solution by a gas stream is not appreciably affected by the rate of dehydration of methylene glycol. A few experiments are reported on the application of the chemical scavenger method to measure the rate of the reaction CH 3 CH(OH) 2 → CH 3 CHO+H 2 O, and the results compared with those obtained by other methods.

Mechanism of hydration and isomerisation of 4-ethylidene-2,6-di-tert-butyl-2,5-cyclohexadien-1-one. Kinetics, acid-base catalysis and solvent deuterium isotope effects

1979 ◽  
Vol 44 (1) ◽  
pp. 110-122 ◽  
Author(s):  
Jiří Velek ◽  
Bohumír Koutek ◽  
Milan Souček
Keyword(s):  
Aqueous Medium ◽  
Rate Equation ◽  
Kinetic Data ◽  
Isotope Effects ◽  
Base Catalysis ◽  
Quinone Methide ◽  
Reaction Products ◽  
Acid Base ◽  
Deuterium Isotope Effects ◽  
Hydroxybenzyl Alcohol

Competitive hydration and isomerisation of the quinone methide I at 25 °C in an aqueous medium in the region of pH 2.4-13.0 was studied spectrophotometrically. The only reaction products in the studied range of pH are 4-hydroxybenzyl alcohol (II) and 4-hydroxystyrene (III). The form of the overall rate equation corresponds to a general acid-base catalysis. The mechanism of both reactions for three markedly separated pH regions is discussed on the basis of kinetic data and solvent deuterium effect.

The mechanism of acid-base catalysis

1991 ◽  
Vol 27 (6) ◽  
pp. 615-619
Author(s):  
K. K. Kalninysh
Keyword(s):  
Base Catalysis ◽  
Acid Base

International Symposium on Acid–Base Catalysis V (ABC-V), Puerto Vallarta, Mexico, June 27th–July 1st 2005

2006 ◽  
Vol 116 (2) ◽  
pp. 89
Author(s):  
Carlos R. Apesteguía ◽  
Hideshi Hattori
Keyword(s):  
International Symposium ◽  
Base Catalysis ◽  
Acid Base

The Acid-Base Catalysis of the Mutarotation of Glucose

1965 ◽  
Vol 4 (11) ◽  
pp. 964-965
Author(s):  
Hermann Schmid ◽  
Günther Bauer
Keyword(s):  
Base Catalysis ◽  
Acid Base

Concept of acid–base catalysis by metal sulfides

2009 ◽  
Vol 144 (3-4) ◽  
pp. 350-357 ◽  
Author(s):  
A.N. Startsev
Keyword(s):  
Base Catalysis ◽  
Metal Sulfides ◽  
Acid Base

International Symposium on Acid–Base Catalysis IV (ABC IV), Matsuyama, Japan, 7–12 May 2001

2002 ◽  
Vol 73 (1-2) ◽  
pp. 1
Author(s):  
Tsutomu Yamaguchi ◽  
Hideshi Hattori ◽  
Wolfgang F Hölderich
Keyword(s):  
International Symposium ◽  
Base Catalysis ◽  
Acid Base
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