Spectral characteristics of the ? (OH) infrared bands and enthalpy of carboxylic acid-base H-complexes

1974 ◽  
Vol 20 (5) ◽  
pp. 645-648
Author(s):  
A. A. Mashkovskii ◽  
V. P. Glazunov ◽  
S. E. Odinokov
Keyword(s):  
Carboxylic Acid ◽  
Spectral Characteristics ◽  
Acid Base

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.

UV and IR Spectral Characteristics of Chloramben in Selected Environments

Weed Science ◽  
1976 ◽  
Vol 24 (1) ◽  
pp. 107-114 ◽  
Author(s):  
V. E. Berkheiser ◽  
J. L. Ahlrichs
Keyword(s):  
Ir Spectra ◽  
Water Content ◽  
Absorption Spectra ◽  
Spectral Characteristics ◽  
Uv Absorption ◽  
Hydration Water ◽  
Carboxyl Group ◽  
Amino Group ◽  
Acid Base ◽  
Uv Absorption Spectra

Ultraviolet (UV) absorption spectra were recorded of chloramben (3-amino-2,5-dichlorobenzoic acid) and selected relatives in solutions of different pH's. From these spectra, the Broensted acid-base properties of chloramben were deduced. Interpretations of solution spectra were applied to UV absorption spectra of chloramben adsorbed onto Ca-montmorillonite at low water content. Infrared (IR) transmittance spectra were recorded of chloramben and selected derivatives in KBr pellets and band assignments were made. Interpretations of these spectra were also applied to IR spectra of chloramben adsorbed onto Ca-montmorillonite at low water content. Both UV and IR measurements indicated that protonation of the amino group occurs and that the carboxyl group of chloramben is strongly hydrogen-bonded to the hydration water of the interlayer cations.

Spectrofluorimetric Study of the Inclusion Complex of 7-Hydroxymethylnalidixic Acid with γ-Cyclodextrin in Aqueous Solution

1997 ◽  
Vol 51 (5) ◽  
pp. 684-688 ◽  
Author(s):  
Isabel Durán-Merás ◽  
Arsenio Muñoz De La Peña ◽  
Francisco Salinas ◽  
Isabel Rodríguez Cáceres
Keyword(s):  
Aqueous Solution ◽  
Inclusion Complex ◽  
Formation Constant ◽  
Spectral Characteristics ◽  
Stoichiometric Ratio ◽  
Acid Base ◽  
Method Of Determination ◽  
Cyclodextrin Cavity ◽  
Complexation Process

A fluorimetric study on the spectral characteristics and acid-base behavior of 7-hydroxymethylnalidixic acid has been performed. The host–guest complexation process between γ-cyclodextrin and 7-hydroxymethylnalid ixic acid has also been investigated by fluorescence spectroscopy. Scatchard and Benesi-Hildebr and methods have been applied to determine the stoichiometry of the complex, and a 1:1 stoichiometric ratio has been established. A K1 = 118 ± 25 M−1 formation constant has been calculated for the inclusion complex, by using the changes produced on the fluorescence of 7-hydroxymethylnalid ixic acid, when it is included on the hydrophobic cyclodextrin cavity. A fluorimetric method of determination of 7-hydroxymethylnalid ixic acid, in γ-cyclodextrin aqueous solution, has been proposed. The analytical parameters and detection and quantification limits of the method have been determined.

scholarly journals SPECTROPHOTOMETRIC STUDY OF ACID-BASE PROPERTIES OF SPATIAL-DISTORTED DERIVATIVES OF PORPHYRINS IN ACETONITRILE

2018 ◽  
Vol 59 (6) ◽  
pp. 49 ◽  
Author(s):  
Yulia B. Ivanova ◽  
Svetlana G. Puhovskaya ◽  
Nugzar Zh. Mamardashvili ◽  
Oscar I. Koifman
Keyword(s):  
Absorption Spectra ◽  
Molecular Form ◽  
Spectral Characteristics ◽  
Reaction System ◽  
Spectrophotometric Titration ◽  
Spectrophotometric Study ◽  
Acidic Properties ◽  
Acid Base ◽  
Electron Absorption ◽  
Base Properties

Spectrophotometric titration method was used to study the acidic properties of: 5,10,15,20-tetrakis(thienyl-2-yl)-2,3,7,8,12,13,17,18-octaethylporphyrin (I), 5,10,15,20-tetrakis(4’-t-butylphenyl)-2,3,7,8,12,13,17,18-octaethylporphyrin (II), 5,10,15,20-tetrakis(3,5-di-t-butylphe-nyl)-2,3,7,8,12,13,17,18-octaethylporphyrin (III), 5,10,15,20-tetraphenyl-2,3,7,8,12,13,17,18-octaethylporphyrin (IV), 5,15-bis(4’-methoxyphenyl)-10,20-bis(4-nitro-phenyl)-2,8,12,18-tetrame-thyl-3,7,13,17-tetraarylporphyrin (V), 5,15-bis(4’-methoxyphenyl)-10,20-diphenyl-2,3,7,8,12,13, 17,18-octaethylporphyrin (VI), 5,15-bis(4’-methoxyphenyl)-2,8,12,18-tetramethyl-3,7,10,13,17,20-hexaethylporphin (VII), 5,10,15,20-tetrakis(4’-methoxyphenyl)-2,3,7,8,12,13,17,18-octaethylpor-phyrin (VIII) in the presence of a deprotonated agent, 1,8-diazabicyclo[5.4.0] undec-7-ene, in acetonitrile. Under deprotonation two families of spectral curves in the absorption spectra, having its own system of isobestic points, are formed. Electron absorption spectrum of molecular form transforms gradually into the spectrum of the final form of dianion with titrant concentration increase. Determination of the coordinates of the inflection (and the corresponding concentration of DBU) on the titration curve  allowed us to distinguish two areas in the electron absorption spectra of the reaction system, which are likely belong to the first and second steps of deprotonation, namely, to the formation of mono- and dianionic forms (HP–  and P2–) of the compound. Spectral characteristics of the ionized forms and combined ionization constant for the first and second steps (lgКа1 and lgКа2) were revealed. At the first step in the order of decreasing acidic properties of the ligands the compounds form a series of: III< V< VIII< VI < VII< II< IV < I; at the second step in decreasing order of the acidic properties of the ligands the compounds form a series of:.III < V < VI < II <VIII< VII < IV < I. The effect of structural and electronic properties of substituents on acid-base properties of porphyrins is analyzed. Thus, chemical modification of the macrocycle can lead to direct changes in acid-base properties of supramolecular macroheterocyclic ligands and can be a powerful tool to control the reactivity of compounds of the porphyrins class.

Acid-base behavior of carboxylic acid groups covalently attached at the surface of polyethylene: The usefulness of contact angle in following the ionization of surface functionality

Langmuir ◽  
1985 ◽  
Vol 1 (6) ◽  
pp. 725-740 ◽  
Author(s):  
Stephen Randall Holmes-Farley ◽  
Robert H. Reamey ◽  
Thomas J. McCarthy ◽  
John Deutch ◽  
George M. Whitesides
Keyword(s):  
Contact Angle ◽  
Carboxylic Acid ◽  
Acid Base ◽  
Surface Functionality ◽  
Carboxylic Acid Groups
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