Ionization constants of benzoic and mononitrobenzoic acids in formamide

1972 ◽  
Vol 25 (5) ◽  
pp. 941 ◽  
Author(s):  
UN Dash ◽  
B Nayak
Keyword(s):  
Benzoic Acid ◽  
Ionization Constants ◽  
Weak Acids ◽  
General Behaviour ◽  
Nitrobenzoic Acid

The ionization constants of benzoic acid and of three mononitrobenzoic acids, at 25� in formamide, have been determined from the measurements of the electro-motive forces of the cells Pt,H2/HA(m1),KA(m2)KCl(m3)AgCl-Ag The values of the ionization constants for benzoic acid, o-nitrobenzoic acid, m-nitro-benzoio acid, and p-nitrobenzoic acid thus calculated from e.m.f. data are 4.37 x 10-7, 3.89 x 10-5, 3.98 x 10-6 and 1.32 x 10-6, respectively. These values are smaller than those in water, and are in agreement with a general behaviour exhibited by weak acids in solvents of this class.

THE IONIZATION CONSTANTS OF p-NITROPHENYLACETIC AND PHENYLMALONIC ACIDS

1933 ◽  
Vol 8 (5) ◽  
pp. 447-449 ◽  
Author(s):  
Steward Basterfield ◽  
James W. Tomecko
Keyword(s):  
Benzoic Acid ◽  
Nitro Group ◽  
Malonic Acid ◽  
Phenylacetic Acid ◽  
Ionization Constants ◽  
Side Chain ◽  
Cooh Group ◽  
Conductivity Data ◽  
Nitrobenzoic Acid ◽  
Phenylmalonic Acid

The ionization constants of p-nitrophenylacetic and phenylmalonic acids have been determined from conductivity data. The value of K for p-nitrophenylacetic acid at 25 °C. is 1.04 × 10−4, about twice that of phenylacetic acid. The nitro group in the nucleus has not as powerful an effect on the ionization when the COOH group is in the side chain as it has when both nitro group and COOH are in the nucleus. K for p-nitrobenzoic acid is six times as great as K for benzoic acid. K for phenylmalonic acid is 2. 77 × 10−3 as compared with 1.6 × 10−3 for malonic acid.

Equivalence Points and Inflexion Points in Acid-Base Titration Curves

1963 ◽  
Vol 16 (5) ◽  
pp. 759 ◽  
Author(s):  
RH Stokes
Keyword(s):  
Strong Acid ◽  
Ionization Constants ◽  
Weak Acids ◽  
Acid Base ◽  
Strong Base ◽  
Titration Curves ◽  
Acid Base Titration

General equations are derived for the relation between pH and stoichiometric degree of neutralization in the titration of monoprotic and diprotic weak acids (or bases) with strong acid or strong base. From these equations the number and position of inflexion points in the curves is derived, and their relation to the equivalence points is shown. Methods for determining ionization constants from inflexion points are discussed.

Multivariate analysis of data for the ionization of weak acids in water – dimethyl sulfoxide solvent mixtures

1981 ◽  
Vol 59 (15) ◽  
pp. 2350-2357 ◽  
Author(s):  
John T. Edward ◽  
Michael Sjöström ◽  
Svante Wold
Keyword(s):  
Multivariate Analysis ◽  
Function Theory ◽  
Component Model ◽  
Ionization Constants ◽  
Solvent Mixtures ◽  
Acidity Function ◽  
Weak Acids ◽  
Chemical Type ◽  
Two Component ◽  
Components Analysis

The ionization constants p(sKa) reported for 41 weak acids of varying chemical type in ten water–DMSO solvent mixtures have been analysed by the SIMCA version of principal components analysis. This shows the data to fit a two-component model. The significance of the results for acidity function theory is discussed.

scholarly journals The SPI1 Gene, Encoding a Glycosylphosphatidylinositol-Anchored Cell Wall Protein, Plays a Prominent Role in the Development of Yeast Resistance to Lipophilic Weak-Acid Food Preservatives

2006 ◽  
Vol 72 (11) ◽  
pp. 7168-7175 ◽  
Author(s):  
T. Simões ◽  
N. P. Mira ◽  
A. R. Fernandes ◽  
Isabel Sá-Correia
Keyword(s):  
Cell Wall ◽  
Transcription Factor ◽  
Acetic Acid ◽  
Benzoic Acid ◽  
Acid Stress ◽  
Weak Acid ◽  
Cell Wall Protein ◽  
Weak Acids ◽  
Food Preservatives ◽  
Cell Wall Porosity

ABSTRACT The Saccharomyces cerevisiae SPI1 gene encodes a member of the glycosylphosphatidylinositol-anchored cell wall protein family. In this work we show results indicating that SPI1 expression protects the yeast cell from damage caused by weak acids used as food preservatives. This is documented by a less extended period of adaptation to growth in their presence and by a less inhibited specific growth rate for a parental strain compared with a mutant with SPI1 deleted. Maximal protection exerted by Spi1p against equivalent concentrations of the various weak acids tested was registered for the more lipophilic acids (octanoic acid, followed by benzoic acid) and was minimal for acetic acid. Weak-acid adaptation was found to involve the rapid activation of SPI1 transcription, which is dependent on the presence of the Msn2p transcription factor. Activation of SPI1 transcription upon acetic acid stress also requires Haa1p, whereas this recently described transcription factor has a negligible role in the adaptive response to benzoic acid. The expression of SPI1 was found to play a prominent role in the development of yeast resistance to 1,3-β-glucanase in benzoic acid-stressed cells, while its involvement in acetic acid-induced resistance to the cell wall-lytic enzyme is slighter. The results are consistent with the notion that Spi1p expression upon weak-acid stress leads to cell wall remodeling, especially for the more lipophilic acids, decreasing cell wall porosity. Decreased cell wall porosity, in turn, reduces access to the plasma membrane, reducing membrane damage, intracellular acidification, and viability loss.

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.

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