Acid-Base Relationships and Tautomeric Equilibria in m-Aminobenzoic Acid, 3-Amino-1-naphthoic Acid, and 4-Amino-2-naphthoic Acid

1961 ◽  
Vol 14 (2) ◽  
pp. 237 ◽  
Author(s):  
A Bryson ◽  
RW Matthews
Keyword(s):  
Aqueous Solution ◽  
Methyl Esters ◽  
Ionization Constants ◽  
Aminobenzoic Acid ◽  
Naphthalene Ring ◽  
Acid Base ◽  
Tautomeric Equilibria ◽  
Naphthoic Acid

The first and second ionization constants have been determined in aqueous solution of m-aminobenzoic acid, 3-amino-1-naphthoic acid, and 4-amino-2-naphthoic acid. From published values of the ionization constants for the methyl esters, the ionization constants have been evaluated for the four equilibria involved in each case and estimates have been made of the effects of the substituents NH3+ and NH2 on the ionization of the COOH, and of the substituents COOH and COO- on the ionization of the NH3+ group. These values and the tautomeric constants are interpreted in terms of structure and are discussed in relation to previous studies on substitution in the naphthalene ring.

The ionization constants of p-Aminobenzoic Acid in Aqueous solution at 25°C

1957 ◽  
Vol 10 (2) ◽  
pp. 128 ◽  
Author(s):  
RA Robinson ◽  
AI Biggs
Keyword(s):  
Aqueous Solution ◽  
Benzoic Acid ◽  
Ionization Constants ◽  
Aminobenzoic Acid ◽  
Zwitterion Formation

The ionization constants of benzoic acid and of four esters of p-aminobenzoic acid, as well as the two ionization constants of p-aminobenzoic acid itself, have been deter- mined by spectrophotometric measurements. The extent of zwitterion formation in p-aminobenzoic acid is discussed.

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.

The influence of β-cyclodextrin on acid–base and tautomeric equilibrium of fluorescein dyes in aqueous solution

2010 ◽  
Vol 345 (13) ◽  
pp. 1882-1890 ◽  
Author(s):  
Larisa N. Bogdanova ◽  
Nikolay O. Mchedlov-Petrossyan ◽  
Natalya A. Vodolazkaya ◽  
Alexander V. Lebed
Keyword(s):  
Aqueous Solution ◽  
Tautomeric Equilibrium ◽  
Acid Base ◽  
Fluorescein Dyes

THE ACIDITY OF SOME AROMATIC FLUORO ALCOHOLS AND KETONES

1960 ◽  
Vol 38 (3) ◽  
pp. 399-406 ◽  
Author(s):  
Ross Stewart ◽  
R. Van der Linden
Keyword(s):  
Aqueous Solution ◽  
Nitro Compounds ◽  
Ionization Constants

A series of five trifluoroacetophenones and five phenyl trifluoromethyl carbinols have been synthesized and their ionization constants in water measured. They are the unsubstituted, p-methoxy, p-methyl, m-bromo, and m-nitro compounds. The ketones exist as hydrates in aqueous solution and each is about two pK units stronger than the corresponding alcohol. The acidities of both series are correlated by the Hammett relation with ρ values of 1.11 and 1.01 for the ketone hydrates and alcohols respectively. The acid strengths vary from a pKa of 9.18 for m-nitro-α,α,α-trifluoroacetophenone to 12.24 for p-methoxyphenyl trifluoromethyl carbinol.

Synthesis, and Acid–Base and DNA-Binding Properties of a Thiophen-Appended Ruthenium Complex

2011 ◽  
Vol 64 (2) ◽  
pp. 206 ◽  
Author(s):  
Hong Luo ◽  
Zhi-Ping Wang ◽  
An-Guo Zhang ◽  
Ke-Zhi Wang
Keyword(s):  
Dna Binding ◽  
Density Functional ◽  
Ruthenium Complex ◽  
Theoretical Calculations ◽  
Ionization Constants ◽  
Acid Base ◽  
Binding Properties ◽  
Emission Quenching ◽  
Melting Experiments ◽  
Dna Binding Properties

2-(5-Phenylthiophen-2-yl)-1H-imidazo[4,5-f][1,10]phenanthroline (Hptip) and its RuII complex [Ru(bpy)2(Hptip)](PF6)2 (where bpy = 2,2′-bipyridine) have been synthesized and characterized by elemental analysis, 1H NMR spectroscopy, and mass spectrometry. The acid–base properties of the complex were studied by UV-visible and luminescence spectrophotometric pH titrations, and ground- and excited-state acidity ionization constants were derived. The DNA-binding properties of [Ru(bpy)2(Hptip)](PF6)2 were also investigated by means of UV-vis and emission spectroscopy, salt effects, steady-state emission quenching by [Fe(CN)6]4–, DNA competitive binding with ethidium bromide, DNA melting experiments, and viscosity measurements. Density functional theoretical calculations were also carried out in order to understand the DNA binding properties.

Ionic Equilibria and pH

2021 ◽  
pp. 276-312
Author(s):  
Christopher O. Oriakhi
Keyword(s):  
Worked Examples ◽  
Ionization Constants ◽  
Acid Base ◽  
Buffer Solution ◽  
Ph Titration ◽  
Titration Curves ◽  
Ionic Equilibria ◽  
Common Ion ◽  
The Common ◽  
Hasselbalch Equation

Ionic Equilibria and pH reviews the quantitative aspects of aqueous acid-base chemistry. Definitions and concepts are presented and appropriate worked examples illustrate calculations of concentration, pH and ionization constants. Acid-base properties of salts (salt hydrolysis) is introduced and explained along with the common-ion effect and calculation of hydrolysis constants. Equilibria of acid-base buffers with respect to buffer preparation, calculating the pH of a buffer solution and application of the Henderson-Hasselbalch equation, buffer range and buffer capacity is discussed. Determining the pH during acid-base titrations, selecting the appropriate acid-base indicators, and generating pH titration curves are explained.

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