Dissociation equilibria of picric acid in the binary N, N-dimethylformamide/2-methoxyethanol solvent system

1991 ◽  
Vol 69 (3) ◽  
pp. 509-517 ◽  
Author(s):  
Andrea Marchetti ◽  
Carlo Preti ◽  
Mara Tagliazucchi ◽  
Lorenzo Tassi ◽  
Giuseppe Tosi
Keyword(s):  
Dissociation Constant ◽  
Picric Acid ◽  
Solvent System ◽  
Solvent Mixture ◽  
Statistical Weight ◽  
Nonaqueous Solvent ◽  
Solvent Mixtures ◽  
Best Fitting ◽  
Complete Form ◽  
Experimental Values

Three empirical equations are proposed to fit the experimental values of the dissociation constant for picric acid, chosen as guide-solute working in the N, N-dimethylformamide/2-methoxyethanol solvent system. The work was performed operating at 19 temperatures ranging from − 10 to + 80 °C in the pure solvents and in their nine mixtures, identified by the mole fraction (X) of one component. This empirical treatment, which describes the dependence of the dissociation constant on temperature and composition of the solvent mixture, is represented by functions of the type K = K(T), K = K(X), and K = K(T, X). The K = K(T, X) equation in its complete form is composed of 20 terms, some of which can be eliminated because of small statistical weight; the number and type of these terms vary on passing from one solvent system to another and the best-fitting form is suggested. A comparison among various K = K(T, X) equations proposed in the present and in previous works has been made. Key words: dissociation equilibria, binary nonaqueous solvent mixtures, picric acid, N,N-dimethylformamide, 2-methoxyethanol.

scholarly journals Viscosity models for bitumen–solvent mixtures

2021 ◽  
Vol 11 (3) ◽  
pp. 1505-1520
Author(s):  
Olalekan S. Alade ◽  
Dhafer A. Al Shehri ◽  
Mohamed Mahmoud ◽  
Samuel Olusegun ◽  
Lateef Owolabi Lawal ◽  
...  
Keyword(s):  
Heavy Oil ◽  
Shear Force ◽  
Solvent System ◽  
High Viscosity ◽  
Solvent Mixture ◽  
Viscosity Reduction ◽  
Solvent Mixtures ◽  
Viscosity Models ◽  
Reservoir Conditions ◽  
Viscosity Modeling

AbstractViscosity is the resistance of a material to continuous deformation exerted by shear force. High viscosity, which is sometimes greater than 1 million mPa s, at the initial reservoir conditions, is a major challenge to recovery, production, and transportation of bitumen. Addition of organic solvents or diluents with bitumen leads to significant viscosity reduction and forms the basis for the steam/solvent-assisted recovery methods of extra-heavy oil and bitumen. Therefore, modeling and predicting viscosity of bitumen–solvent mixture has become an important step in the development of solvent-assisted system. The aim of this article is to present a concise survey of the various viscosity models that have been proposed to predict the viscosity of bitumen–solvent mixtures, and make comparative discussion on their applicability. Available reports revealed that the accuracy of a model to predict the viscosity of bitumen–solvent mixtures depends on various factors including the type and concentration of solvents, and the properties of the bitumen. Thus, no model has been found to have absolute capability to predict the viscosity for all mixtures. Therefore, there is room for further improvement on the viscosity modeling of bitumen–solvent system for wider applications.

Solubility prediction of anthracene in nonaqueous solvent mixtures using a combination of Jouyban-Acree and Abraham models

2006 ◽  
Vol 84 (6) ◽  
pp. 874-885
Author(s):  
Abolghasem Jouyban ◽  
Maryam Khoubnasabjafari ◽  
William E Acree, Jr.
Keyword(s):  
Data Sets ◽  
Nonaqueous Solvent ◽  
Solvent Mixtures ◽  
Structure Property ◽  
Solubility Prediction ◽  
Structure Property Relationships ◽  
Solvent Model ◽  
Quantitative Structure Property Relationships ◽  
Experimental Values ◽  
The Individual

The applicability of previously developed quantitative structure-property relationships was extended to predict the solubility of anthracene in nonaqueous binary and ternary solvent mixtures. The accuracy of the proposed methods was evaluated using 81 solubility data sets collected from the literature. The individual and mean percentage deviation (IPD and MPD) of experimental and computed solubilities were calculated as accuracy criteria. The computations were carried out using experimental and predicted mole fraction solubility of anthracene in monosolvent systems for binary and ternary solvent systems. The overall MPD of solubility prediction using experimental values in monosolvents varied from 5.2% to 4.2% and from 16.5% to 10.7% for binary and ternary solvents, using water to solvent and gas to solvent solvational parameters, respectively. The IPD distribution was better for the gas to solvent model. The corresponding ranges for the predicted solubility of anthracene in monosolvents were 47.9% to 28.1% and 23.9% to 22.5% for binary and ternary solvents, respectively, and IPD distribution was more favourable for the gas to solvent model. In general, the models derived from gas to solvent coefficients provided more accurate predictions and are recommended for practical applications.Key words: solubility, prediction, cosolvency, anthracene, Abraham model, Jouyban-Acree model.

ΔS°t – as a Structural Probe – a Critical Analysis of the Method and Determination of Structure of Aquo-Alcoholic Mixtures

2003 ◽  
Vol 217 (6) ◽  
pp. 615-636 ◽  
Author(s):  
S. K. Gumtya ◽  
G. Bandyopadhyay ◽  
S. C. Lahiri
Keyword(s):  
Thermodynamic Properties ◽  
Structural Characteristics ◽  
Solvent System ◽  
Mirror Image ◽  
Critical Examination ◽  
Solvent Mixtures ◽  
Structural Probe ◽  
Thermodynamic Measurements ◽  
Alcoholic Mixtures ◽  
Errors Analysis

AbstractAttempts were made for a critical examination of the use of ΔS°t as a structural probe to study the ion induced perturbations on aquo-alcoholic solvent mixtures. The division of the thermodynamic properties of TATB (tetraphenyl arsonium tetraphenyl borate) in solution into equal parts is not free from defects. Naturally, the calculation of single ion values based on TATB is also problematic. Dissection of the single ion values like TΔS°t(ion) as suggested by Kundu is full of errors. Analysis shows TΔS°t(ion) to be an insensitive parameter to determine the structural characteristics of aquo-alcoholic mixtures. Structure of aquo-alcoholic mixtures should be determined from the excess thermodynamic properties of mixing, excess dielectric properties of mixing, excess polarizabilities, the correlation parameter “g” etc. Other properties like ultrasonic sound absorption, excess volume and viscosity of mixing were found to be useful. Ion induced perturbations of any solvent system will be dictated by the structure of the particular solvent system. A knowledge of the structure of the aquo-alcoholic mixtures is imperative to develop an idea regarding ion induced perturbations as mirror image relations because of compensation of ΔH° and TΔS° (and of ΔH°t and TΔS°t) will be observed in any solvent system. The thermodynamic measurements provide a summary of all interaction energies over a long time. To comprehend the rational structural details of the solvent systems, accurate thermodynamic measurements alongwith relaxation experiments providing high time and good structural resolutions are necessary.

Silicon Micromachined Infrared Thin-Layer Cell for In Situ Spectroelectrochemical Analysis of Aqueous and Nonaqueous Solvent System

2005 ◽  
Vol 17 (11) ◽  
pp. 959-964 ◽  
Author(s):  
Kwang-Seok Yun ◽  
Segyeong Joo ◽  
Hong-Jeong Kim ◽  
Juhyoun Kwak ◽  
Euisik Yoon
Keyword(s):  
Thin Layer ◽  
Solvent System ◽  
Nonaqueous Solvent ◽  
Layer Cell ◽  
Thin Layer Cell

scholarly journals Fast real-time monitoring of entacapone crystallization and characterization of polymorphs via Raman spectroscopy, statistics and SWAXS

2014 ◽  
Vol 64 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Tomislav Jednačak ◽  
Aden Hodzic ◽  
Otto Scheibelhofer ◽  
Marijan Marijan ◽  
Johannes G. Khinast ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Optical Probe ◽  
Solvent Mixture ◽  
Binary Solvent ◽  
Solvent Mixtures ◽  
Starting Point ◽  
Principal Components Method ◽  
Components Method

Abstract Crystallization of the drug entacapone from binary solvent mixtures was monitored in situ using a Raman optical probe. The recorded Raman spectra and statistical analysis, which included the principal components method and indirect hard modeling made it possible to estimate the starting point of crystallization, to assess crystallization temperatures and to provide information on the polymorphic content of the mixture. It was established that crystallization temperatures were proportional to the volume content of the solvent in mixtures. The samples were also evaluated off-line via Raman spectroscopy and SWAXS. The collected data showed the presence of forms b and g in all solvent mixtures. In a toluene/methanol 30:70 mixture, in addition to forms b and g, at least one of the forms A, D or a was also indicated by SWAXS. The results have shown that the presence of a particular polymorph is strongly dependent on the nature and portion of the solvent in the binary solvent mixture.

The Ionization of Picric Acid in Ethanol–Sulfolane and t-Butyl Alcohol – Sulfolane Mixtures at 30 °C

1975 ◽  
Vol 53 (11) ◽  
pp. 1651-1656 ◽  
Author(s):  
Maurizio Castagnolo ◽  
Angelo De Giglio ◽  
Angelo Dell'atti ◽  
Giuseppe Petrella
Keyword(s):  
Association Constant ◽  
Composition Range ◽  
Dissociation Constants ◽  
Picric Acid ◽  
Preferential Solvation ◽  
Butyl Alcohol ◽  
Weak Acid ◽  
Solvent Composition ◽  
Solvent Mixtures ◽  
Simple Dissociation

Dissociation constants at 30 °C of picric acid have been determined by a spectrophotometric method in ethanol–sulfolane and t-butyl alcohol – sulfolane mixtures over the entire solvent composition range. Picric acid behaves as a weak acid in all mixtures. In pure sulfolane, picric acid undergoes simple dissociation for c < 0.08 M (pKHPI = 7.6). At concentrations higher than 0.08 M more complex equilibria have been observed and interpreted assuming Pi(HPi)2− as the principal picrate species in solution. Complex behavior of dependence of association constant on solvent composition was observed; in both solvent mixtures as sociation of picric acid decreases with decrease of dielectric constant. This behavior was discussed in terms of preferential solvation of picric acid by alcohols, the more basic components of the mixtures. A reaction mechanism of four alcohol molecules with one acid molecule accounts for the behavior observed.

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