Conductance studies in amide–water mixtures. VI. Nitrates of sodium, potassium, and ammonium in N,N-dimethylformamide–water mixtures at 25 °C

1984 ◽  
Vol 62 (6) ◽  
pp. 1051-1056 ◽  
Author(s):  
Lal Bahadur ◽  
M. V. Ramanamurti
Keyword(s):  
Association Constant ◽  
Solvent Mixture ◽  
Dielectric Constants ◽  
Solvent Mixtures ◽  
Walden Product ◽  
Sodium Potassium ◽  
Conductance Data ◽  
Walden Products ◽  
Pass Through ◽  
Limiting Equivalent Conductances

Conductance data for the nitrates of sodium, potassium, and ammonium in N,N-dimethylformamide (DMF) – water mixtures (74.39 ≥ D ≥ 36.11) at 25 °C are reported for the concentration range 0.0003–0.06 mol dm−3. Also densities, viscosities, and dielectric constants of the solvent mixture (DMF–water) are reported at the same temperature. The data have been analysed by the Fuoss (1978) equation excluding the term α. The existence of a maximum in the viscosity at a 1:3 mol ratio of DMF and water is attributed to the formation of a solvated complex DMF•3H2O. The Walden products for all the three salts pass through a maximum while the equivalent conductances show a minimum with the change of DMF content in the solvent mixtures. In any given solvent mixture, the limiting equivalent conductances show the trend NaNO3 < KNO3 < NH4NO3. The existence of a maximum in Walden product is attributed to the dehydration of ions due to presence of the cosolvent (DMF). For all the three salts, the association constant was negligible (KA < 10) in all the solvent mixtures studied.

LIMITING CONDUCTANCE OF LYONIUM AND LYATE IONS

1959 ◽  
Vol 37 (1) ◽  
pp. 173-177 ◽  
Author(s):  
Martin Kilpatrick
Keyword(s):  
Mixed Solvents ◽  
Direct Determination ◽  
Solvent Mixture ◽  
Dielectric Constants ◽  
Proton Mobility ◽  
Anhydrous Hydrogen Fluoride ◽  
Ice Leads ◽  
Hydrogen Bonded Systems ◽  
High Dielectric ◽  
Strong Acids

The problem of proton mobility has been considered in H2O–CH3OH, H2O–D2O, and H2O–H2O2 solvents from the current viewpoint of the mechanism of proton mobility for aqueous solutions. Mixed solvents are more complicated in that one must consider the relative basicity and acidity of the species competing for the protons. It is concluded that for dilute solutions of HClO4, where water is replaced by hydrogen peroxide, the decrease in equivalent conductance relative to that of KCl in the same solvent mixture is due to the partial elimination of the proton transfer process.For highly acidic non-aqueous solvents of high dielectric constants such as HF, HCN, and HCOOH, the problem of the weakness of the usual "strong" acids of aqueous solution makes a direct determination of the limiting equivalent conductances difficult. In the case of anhydrous hydrogen fluoride the available experimental evidence indicates that the limiting conductance of the lyonium ion is approximately the same as that of the potassium ion but the lyate ion has a higher limiting conductance than other stable anions.The higher proton mobility in ice leads one to expect that hydrogen-bonded systems may be found where the conductivity may approach that of electronic semiconductors.

Conductimetric studies of ionic association of tetraalkylammonium halides in iso-propanol + water mixtures at 25 °C. Part II.

1988 ◽  
Vol 66 (7) ◽  
pp. 1720-1727 ◽  
Author(s):  
Auaz Ahmad Ansari ◽  
M. R. Islam
Keyword(s):  
Dielectric Constant ◽  
Association Constant ◽  
Ionic Association ◽  
Size Parameter ◽  
Solvent Interactions ◽  
Tetraalkylammonium Ions ◽  
Conductance Data ◽  
Electrical Conductivities ◽  
Ion Size ◽  
Tetraalkylammonium Halides

Electrical conductivities of Me4NBr, Et4NBr, Pr4NBr, Bu4NBr, and Bu4PBr have been measured in isopropanol + water (2-PrOH + H2O) mixtures covering the approximate range of dielectric constant (71.40 ≥ D ≥ 19.40) at 25 °C. The conductance data have been analysed by using the Fuoss-1978 (F78) conductance equation and the results compared with those obtained from the Fuoss–Onsager–Skinner (FOS) equation. The values of the limiting equivalent conductance, Λ0, the association constant, KA, and the distance of ion-size parameter [Formula: see text] are computed from these data. A better fit of the conductance data was provided by the F78 equation. Ion–solvent interactions and effective sizes of tetraalkylammonium ions are also discussed in order to understand the magnitude of the ionic association. The overall association behaviour of these salts has been found to increase with decrease in dielectric constant of the medium.

Comparative studies of energy saving polymers and fabrication of high performance transparent polymer by solvent bonding

2018 ◽  
Vol 39 (1) ◽  
pp. 68-75
Author(s):  
S.P. Aadhy ◽  
T. Hema Sinega ◽  
C. Karthikeyan ◽  
S. Akshay ◽  
Mohan Kumar Pitchan ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Energy Saving ◽  
High Performance ◽  
Solvent Mixture ◽  
Heat Transfer Analysis ◽  
Compression Moulding ◽  
Lap Shear ◽  
Visible Wavelengths ◽  
Pass Through ◽  
Solvent Bonding

Abstract This work investigates the possibility of using polyetherimide (PEI) as an energy saving alternative to glass, polymethylmethacrylate (PMMA) and polycarbonate (PC) by carrying out heat transfer analysis and suggests vaporized solvent bonding as a viable bonding technique for the fabrication of PEI. By heat transfer analysis using building energy simulation, it is observed that less energy is expended for space-conditioning of a building with windows made of PEI when compared to glass, PMMA and PC. The compression moulding technique is used to mould PEI and fabrication is done using a solvent mixture of dimethyl sulfoxide and tetrahydrofuran in 1:1 ratio. The optical properties of the bonded specimen are studied using UV-visible spectrophotometry and it is found that PEI does not allow UV wavelength radiation to pass through while transmitting visible wavelengths. The mechanical strength of the bond is tested using lap shear tensile strength test and the type of failure is observed to be cohesive from the structure. This is indicative of the fact that using this particular solvent to bond PEI results in the maximum possible strength.

Conductivity and ionic association of tetraalkylammonium halides in tert-butanol–water mixture at 25 °C

1988 ◽  
Vol 66 (5) ◽  
pp. 1223-1228 ◽  
Author(s):  
Aijaz Ahmad Ansari ◽  
M. R. Islam
Keyword(s):  
Ion Association ◽  
Ionic Association ◽  
Solvent Mixtures ◽  
Water Mixture ◽  
Solvent Interaction ◽  
Tert Butanol ◽  
Ion Association Constants ◽  
Conductance Data ◽  
Ion Size ◽  
Tetraalkylammonium Halides

The molar conductivities of Pr4NBr, Bu4NBr, Pr4NI, and BU4NI have been measured in tert-butanol–water (t-BuOH–H2O) mixtures (61.30 ≥ D ≥ 16.50) over the maximum concentration range (2 × D3 × 10−7 mol dm−3) along with the densities and viscosities of the solvent mixtures at 25 °C. The conductance data have been analysed by using the Fuoss-1978 (F78) conductance equation and the results compared with the values obtained from the Justice (J), Pitt's (P), and Fuoss–Onsager–Skinner (FOS) equations. Molar conductivities at infinite dilution (Λ0), the thermodynamic ion association constants (KA) and the distance or ion-size parameters (R0 or a0) are evaluated from these data. The F78 equation fitted the data better and yielded KA and R values which are in accord with the ion-association theories. The interpretation of these parameters is discussed to provide some insight on the magnitude of the ionic association and the ion–solvent interaction.

The Conductance of the Alkali Halides

1973 ◽  
Vol 28 (7) ◽  
pp. 1149-1151 ◽  
Author(s):  
Giuseppe Petrella ◽  
Maurizio Castagnolo
Keyword(s):  
Dielectric Constant ◽  
Lithium Chloride ◽  
Association Constant ◽  
Alkali Halides ◽  
Solvent Mixtures ◽  
Ion Transfer

The conductometric behaviour, at 35 °C, of solutions of lithium chloride in sulfolane-methanol mixtures was investigated, the concentration of the salt ranging within 0.8 x 10-3 and 8 x 10-3 moles/l and the dielectric constant of the solvent within 42 and 30. Using the Fuoss, Onsager and Skinner treatment, the parameters ⋀0 , αL, A and αA were calculated. An increase of the Waiden products with the sulfolane content of the solution was observed as well as an non-coulomb behaviour of the association constant. Data are discussed and interpreted on the basis of ion transfer energies and the properties of the solute and the solvent mixtures.

scholarly journals The Audio Frequency Conductance Study of Some Metal Succinate Salts in Aqueous Medium at Different Temperatures (Part I: Magnesium, Manganese (II), Barium and Copper Succinates)

2013 ◽  
Vol 2013 ◽  
pp. 1-10
Author(s):  
Kosrat N. Kaka ◽  
Anis A. Al-Najar ◽  
Wali M. Hamad
Keyword(s):  
Molar Conductance ◽  
Audio Frequency ◽  
Walden Product ◽  
Electrical Conductances ◽  
Conductance Data ◽  
Association Reaction ◽  
Different Temperatures ◽  
Quantitative Results ◽  
Strong Electrolytes ◽  
Modified Forms

The audio electrical conductances of aqueous solutions of magnesium, manganese II, barium, and copper succinates have been measured at various temperatures in the range of 298.15 K to 313.15 K, using an audio frequency conductance bridge. The evaluation of conductance data was carried out by minimisation technique using the theoretical equations of the complete and modified forms of Pitts (P) and Fuoss-Hsia (F-H), each a three-parameter equation, association constant (KA), molar conductance (Λm), and distance parameter (a). Quantitative results showed that these salts do not behave as “strong” electrolytes, and that their dissociations are far from complete. The abnormally low conductances of these electrolytes are not due to the presence of electrically neutral molecules but to the ion-pair formation. The Walden product values, as well as the standard thermodynamics functions (ΔH∘,ΔG∘,ΔS∘) for the association reaction at the four temperatures studied, have been evaluated.

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.

scholarly journals Solvent Mixture Optimization in the Extraction of Bioactive Compounds and Antioxidant Activities from Garlic (Allium sativum L.)

Molecules ◽  
2021 ◽  
Vol 26 (19) ◽  
pp. 6026
Author(s):  
Vytória Piscitelli Cavalcanti ◽  
Smail Aazza ◽  
Suzan Kelly Vilela Bertolucci ◽  
João Pedro Miranda Rocha ◽  
Adriane Duarte Coelho ◽  
...  
Keyword(s):  
Binary Mixture ◽  
Bioactive Compounds ◽  
Antioxidant Activities ◽  
Pure Water ◽  
Extraction Procedure ◽  
Solvent Mixture ◽  
Total Phenolic ◽  
Solvent Mixtures ◽  
Garlic Powder ◽  
Dpph Scavenging

Garlic is a health promoter that has important bioactive compounds. The bioactive extraction is an important step in the analysis of constituents present in plant preparations. The purpose of this study is to optimize the extraction with the best proportion of solvents to obtain total phenolic compounds (TPC) and thiosulfinates (TS) from dried garlic powder, and evaluate the antioxidant activities of the optimized extracts. A statistical mixture simplex axial design was used to evaluate the effect of solvents (water, ethanol, and acetone), as well as mixtures of these solvents, after two ultrasound extraction cycles of 15 min. Results showed that solvent mixtures with a high portion of water and pure water were efficient for TPC and TS recovery through this extraction procedure. According to the regression model computed, the most significant solvent mixtures to obtain high TPC and TS recovery from dried garlic powder are, respectively, the binary mixture with 75% water and 25% acetone and pure water. These optimized extracts presented oxygen radical absorbance capacity. Pure water was better for total antioxidant capacity, and the binary mixture of water–acetone (75:25) was better for DPPH scavenging activity. These optimized extracts can be used for industrial and research applications.

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