Studies of the dissociation of 2,4,6-trinitrophenol in aqueous mixtures of methanol and ethanol at 25 °C

1985 ◽  
Vol 63 (11) ◽  
pp. 3129-3132 ◽  
Author(s):  
A. L. De ◽  
A. K. Atta
Keyword(s):  
Acetic Acid ◽  
Benzoic Acid ◽  
Solvent Effect ◽  
Spectrophotometric Method ◽  
Dissociation Constants ◽  
Dispersion Interaction ◽  
Organic Component ◽  
Aqueous Mixtures ◽  
Dispersion Interactions ◽  
The Difference

Thermodynamic dissociation constants (sK)m of 2,4,6-trinitrophenol have been determined at 25 °C in aqueous mixtures containing 30, 50, 70, and 90% by weight of methanol and 30, 50, 70, 90, and 95% by weight of ethanol by spectrophotometric method. Solvent effect on the dissociation of the acid: δ(ΔG0) = 2.303RT[p(sK)N − p(wK)N] shows an unusual behaviour, the value decreases and passes through a minimum and ultimately becomes positive as the proportion of organic component in the solvent is progressively increased. The results have been compared with those of other uncharged acids like acetic acid, benzoic acid available from literature. The difference of behaviour (minimum characteristic in δ(ΔG0) curve) has been attributed to very strong dispersion interaction of trinitrophenolate anion with the organic component of the solvent. The overall behaviour of this acid indicates that solvent effect is an involved process being guided by electrostatic and dispersion interactions besides relative solvent basicities.

Solvent effect on the dissociation of p-nitroanilinium ion in glycerol–water media at 25 °C

1984 ◽  
Vol 62 (11) ◽  
pp. 2245-2248
Author(s):  
Amrita Lal De ◽  
Tapas Kumar De
Keyword(s):  
Solvent Effect ◽  
Dissociation Constants ◽  
Mixed Solvents ◽  
Individual Species ◽  
Aqueous Mixtures ◽  
Free Energies ◽  
Monohydric Alcohol ◽  
Glycerol Water ◽  
Alcohol Water ◽  
The Individual

Thermodynamic dissociation constants (sK) of p-nitroanilinium ion (BH+) have been determined at 25 °C in aqueous mixtures of 10, 30, 50, 70, and 90 wt.% of glycerol (GL) by spectrophotometric measurements. Standard free energies, [Formula: see text], of p-nitroaniline (B) from water to mixed solvents have been evaluated from the measurement of solubilities at 25 °C. p(sK) values decrease with increase in mol% of GL and pass through a minimum and then increase very slowly. The solvent effect on the dissociation, δ(ΔG0) = 2.303RT [p(sK)N – p(wK)N] has been discussed in terms of the standard free energies of transfer [Formula: see text] from water to aqueous mixtures of GL of the uncharged base (B), the hydrochloride of the base (BHCl), hydrochloric acid (HCl), and also in terms of the individual species involved in the dissociation process. The solvent effect in trihydric alcohol – water (GL + H2O) system has been compared with those in dihydric alcohol – water (ethylene glycol + water) and monohydric alcohol – water (ethanol + water) systems available from literature. The much less solvent effect in GL + H2O has been primarily attributed to the contrasting nature of interaction of H+ and of partially charged H atoms of—NH3+ group in BH+ compared to those in other two solvent systems.

Solute–solvent effects in the dissociation of thymolsulfonephthalein (an uncharged acid) in aqueous mixtures of acetonitrile (ACN), urea, and dimethyl sulfoxide (DMSO)

1986 ◽  
Vol 64 (8) ◽  
pp. 1521-1526 ◽  
Author(s):  
A. L. De ◽  
A. K. Atta
Keyword(s):  
Solvent Effect ◽  
Dimethyl Sulfoxide ◽  
Solvent Effects ◽  
Mixed Solvent ◽  
Dissociation Constants ◽  
Aqueous Mixtures ◽  
Solvent Interactions ◽  
Gibbs Energies ◽  
Gibbs Energies Of Transfer ◽  
Solvent Systems

The thermodynamic first dissociation constants, [Formula: see text] of thymolsulfonephthalein (H2A), an uncharged acid, have been determined at 25 °C in aqueous mixtures of 10, 30, 50, 70, and 80 wt% acetonitrile (ACN), 11.52, 20.31, 29.64, and 36.83 wt% urea, 20, 40, 60, and 80 wt% dimethyl sulfoxide (DMSO) by spectrophotometric measurements. The solvent effect represented by ∂(ΔG0) = 2.303RT[p(sK)N − p(wK)N] is found to increase in ACN + H2O system as mol% ACN increases in the solvent. In contrast, the corresponding values in urea + H2O as well as DMSO + H2O solvent systems decrease with increase in proportion of organic component in the solvent, the decrease being sharp in urea + H2O. The results have been discussed in terms of the standard Gibbs energies of transfer of H+ from water to the mixed solvent, [Formula: see text] and the relative values of the standard Gibbs energies of transfer of HA−, [Formula: see text] and of [Formula: see text] in all the solvent systems. The overall dissociation behaviour of the acid (H2A) is found to be dictated by the specific solute-solvent interactions of the species participating in the dissociation equilibria.

Spectrophotometric study of the dissociation of p-nitroanilinium ion in a binary aqueous-dipolar aprotic solvent system (H2O + acetonitrile) at 25 °C: effect of the solvent

1984 ◽  
Vol 62 (9) ◽  
pp. 1776-1779
Author(s):  
A. L. De ◽  
T. K. De
Keyword(s):  
Solvent Effect ◽  
Dissociation Constants ◽  
Spectrophotometric Study ◽  
Solvent System ◽  
Individual Species ◽  
Aqueous Mixtures ◽  
Gibbs Energies ◽  
Gibbs Energies Of Transfer ◽  
Aqueous Mixture ◽  
The Individual

Thermodynamic dissociation constants (SK) of p-nitroanilinium ion (BH+) have been determined at 25 °C in aqueous solutions containing 20, 40, 60, and 80 wt% acetonitrile (ACN) by spectrophotometric measurements. Standard Gibbs energies of transfer, [Formula: see text] (B) of p-nitroaniline (B) from water to other solvents have been evaluated from the measurement of solubilities at 25 °C. Solvent effect on the dissociation of the acid (BH+), δ(ΔG0) = 2.303RT[p(sK) − p(wK], results in a characteristic minimum with a change in the solvent composition. The result in this protic – dipolar aprotic mixture (H2O + ACN) has been compared with that in aqueous mixture of protic solvent (H2O + ethylene glycol) available from literature. The solvent effect has been discussed in terms of the standard Gibbs energies of transfer [Formula: see text], from water to aqueous mixtures of organic co-solvent of the uncharged base (B), the hydrochloride of the base (BHCl), and hydrochloric acid (HCl) and also in terms of the individual species involved in the dissociation process. The results indicate that solvent effect on dissociation is an involved process, guided by the combined effects of various types of solute–solvent interactions of the Brønsted acid and its conjugate base in addition to the relative solvent basicities.

Solvent effect on acid–base clustering between acetic acid and pyridine

1998 ◽  
pp. 95-100 ◽  
Author(s):  
Yoshikatsu Akiyama ◽  
Akihiro Wakisaka ◽  
Fujio Mizukami ◽  
Kengo Sakaguchi
Keyword(s):  
Acetic Acid ◽  
Solvent Effect ◽  
Acid Base

scholarly journals A spectrophotometric method for determination of fluorophore-to-protein ratios in conjugates of the blue fluorophore 7-amino-4-methylcoumarin-3-acetic acid (AMCA)

1990 ◽  
Vol 38 (1) ◽  
pp. 87-94 ◽  
Author(s):  
M W Wessendorf ◽  
S J Tallaksen-Greene ◽  
R M Wohlhueter
Keyword(s):  
Acetic Acid ◽  
Optical Density ◽  
Extinction Coefficient ◽  
Spectrophotometric Method ◽  
Extinction Coefficients ◽  
Beer's Law ◽  
Beer’S Law ◽  
The Given

7-Amino-4-methylcoumarin-3-acetic acid (AMCA) has been found to be a useful fluorophore for immunofluorescence. The present study describes a spectrophotometric method for determining the ratio of moles AMCA to moles protein (or the f/p ratio) in an AMCA-conjugated IgG. The concentration of a substance absorbing light can be determined spectrophotometrically using Beer's Law: Absorbance = Concentration x Extinction coefficient. From Beer's law, one can derive the following formula for determining the f/p ratio of AMCA-IgG conjugates: f/p = (epsilon 280IgG).A350 - (epsilon 350IgG).A280/(epsilon 350AMCA).A280 - (epsilon 280AMCA).A350 where A is the optical density of the conjugate at the given wavelength and epsilon is the extinction coefficient of a substance at the wavelength specified. Using conjugates of model proteins, it was found that the extinction coefficients of the AMCA moiety of AMCA-conjugated protein were 1.90 x 10(4) at 350 nm and 8.29 x 10(3) at 280 nm. Similarly, it was found that the extinction coefficients of swine IgG were 1.56 x 10(3) at 350 nm and 1.26 x 10(5) at 280 nm. Thus, for AMCA-conjugated swine IgG: f/p = (1.26 x 10(5)).A350 - (1.56 x 10(3)).A280/(1.47 x 10(4)).A280 - (6.42 x 10(3)).A350 [corrected]. Based on this formula, the f/p ratios of some AMCA-IgG conjugates useful for immunohistochemistry have been found to range between 6 and 24.

scholarly journals Comparison of organics and heavy metals acute toxicities to Vibrio fischeri

2016 ◽  
Vol 81 (6) ◽  
pp. 697-705 ◽  
Author(s):  
Xuepeng Yang ◽  
Yan Ji ◽  
Fangfang Wang ◽  
Jia Xu ◽  
Xiangzhen Liu ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Cell Death ◽  
Benzoic Acid ◽  
Death Rate ◽  
Vibrio Fischeri ◽  
Reaction Times ◽  
Inhibition Rate ◽  
Cell Death Rate ◽  
Bioluminescence Inhibition ◽  
The Difference

Vibrio fischeri bioluminescence inhibition has been widely used to test acute toxicities of metals and organics contaminants. However, the differences of metals and organics acute toxicities to V. fischeri have not been compared. Here, four heavy metals (Zn2+, Cu2+, Cd2+, Cr6+) and five organics (phenol, benzoic acid, p-hydroxy benzoic acid, nitro-benzene and benzene) acute toxicities to V. fischeri were investigated. Heavy metals toxicities to V. fischeri were increased along with the reaction time, while the organics toxicities kept the same level in different reaction times. In order to explain the difference, the relative cell death rate of V. fischeri was detected. In metals toxicities tests, the bioluminescence inhibition rate of V. fischeri was found to be significantly higher than the relative cell death rate (P<0.05), while for the organics toxicities tests, the cell death rate was similar to the bioluminescence inhibition rate. These results indicated that organics acute toxicities to V. fischeri could reflect the death of cell, but metals acute toxicities to V. fischeri may not lead to the death of cell, just represent the bioluminescence inhibition.

scholarly journals The effectiveness of acetic acid wash protocol and the interpretation patterns of blood contaminated cervical cytology ThinPrep® specimens

CytoJournal ◽  
2015 ◽  
Vol 12 ◽  
pp. 23 ◽  
Author(s):  
Nora K. Frisch ◽  
Yasin Ahmed ◽  
Seema Sethi ◽  
Daniel Neill ◽  
Tatyana Kalinicheva ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Statistical Significance ◽  
Cervical Cytology ◽  
Low Grade ◽  
Squamous Intraepithelial Lesions ◽  
Chi Square ◽  
Chi Square Test ◽  
Acid Wash ◽  
The Difference ◽  
Intraepithelial Lesions

Background: ThinPrep® (TP) cervical cytology, as a liquid-based method, has many benefits but also a relatively high unsatisfactory rate due to debris/lubricant contamination and the presence of blood. These contaminants clog the TP filter and prevent the deposition of adequate diagnostic cells on the slide. An acetic acid wash (AAW) protocol is often used to lyse red blood cells, before preparing the TP slides. Design: From 23,291 TP cervical cytology specimens over a 4-month period, 2739 underwent AAW protocol due to initial unsatisfactory smear (UNS) with scant cellularity due to blood or being grossly bloody. Randomly selected 2739 cervical cytology specimens which did not undergo AAW from the same time period formed the control (non-AAW) group. Cytopathologic interpretations of AAW and non-AAW groups were compared using the Chi-square test. Results: About 94.2% of the 2739 cases which underwent AAW were subsequently satisfactory for evaluation with interpretations of atypical squamous cells of undetermined significance (ASCUS) 4.9% (135), low-grade squamous intraepithelial lesions (LSIL) 3.7% (102), and high-grade squamous intraepithelial lesions (HSIL) 1% (28). From the 2739 control cases, 96.3% were satisfactory with ASCUS 5.5% (151), LSIL 5.1% (139), and HSIL 0.7% (19). The prevalence of ASCUS interpretations was similar (P = 0.33). Although there were 32% more HSIL interpretations in the AAW group (28 in AAW vs. 19 in non-AAW), the difference was statistically insignificant (P = 0.18). AAW category; however, had significantly fewer LSIL interpretations (P = 0.02). The percentage of UNS cases remained higher in the AAW group with statistical significance (P < 0.01). Conclusions: While AAW had a significantly higher percent of UNS interpretations, the protocol was effective in rescuing 94.2% of specimens which otherwise may have been reported unsatisfactory. This improved patient care by avoiding a repeat test. The prevalence of ASCUS and HSIL interpretations between AAW and non-AAW groups were comparable. Though not statistically significant, HSIL interpretations were relatively higher in the AAW group. LSIL interpretations showed lower prevalence in AAW group.

scholarly journals Oxidative Study of Benzaldehyde by Isoqauinolinium Bromo Chromate

2019 ◽  
Vol 16 ◽  
pp. 5354-5359
Author(s):  
Arun Kumar Dwivedi ◽  
K. N. Sharma ◽  
Arvind Prasad Dwivedi
Keyword(s):  
Dielectric Constant ◽  
Acetic Acid ◽  
Complex Formation ◽  
Benzoic Acid ◽  
Neutral Salt ◽  
Kinetics Analysis ◽  
Keto Form ◽  
Acetic Acid Medium ◽  
Oxidative Reaction ◽  
Rate Of Reaction

The kinetics analysis of the oxidative reaction between benzaldehyde and oxidant is quinolinium Bromo chromate was reported in aqueous 40% acetic acid medium at 313 K. The rate of reaction varies first-power of [IQBC] and [H2SO4], whereas fractional-order kinetics was observed for benzaldehyde. The rate constant gradually increases with decrease in dielectric constant of the medium. The neutral salt does not alter the rate. The metal cations (Cu++) slightly accelerate the rate of oxidation when added to reaction mixture. The study rules out the participation of keto form of substrate in complex formation. Benzoic acid was identified as the end-product in stoichiometrically 1:1 based mechanism. The rate law was derived in accordance with the kinetic results.

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