A General Relation Between H0, Acid Concentration, and Water Activity for Strong Acids at Moderate Concentrations

1972 ◽  
Vol 50 (20) ◽  
pp. 3283-3287 ◽  
Author(s):  
T. T. Teng ◽  
F. Lenzi
Keyword(s):  
Equilibrium Constants ◽  
General Relation ◽  
Type Equation ◽  
Strong Acid ◽  
Acidity Function ◽  
Acid Anion ◽  
Degree Of Dissociation ◽  
Hammett Acidity Function ◽  
Hydrated Proton ◽  
Strong Acids

Values of the Hammett acidity function H0 can be correlated for strong acid solutions up to −H0 values of 3.5 via a Bascombe and Bell type equation:[Formula: see text] taking into account the degree of dissociation of the acids. This can be interpreted according to[Formula: see text]and[Formula: see text]Alternatively, an approach based on the treatment of equilibrium constants in terms of mole-fractions yields[Formula: see text]valid for the same acids (H2SO4, HClO4, HCl, and HNO3) and again involving a tri-dehydration of the tetra-hydrated proton. The log of the ratio [Formula: see text] has been found to be proportional to −H0 itself and to be otherwise independent of the nature of the acid anion.

scholarly journals Relations between the Hammett Acidity Function, H0, and Ion Activities in Mixtures of strong Acids and Water.

1960 ◽  
Vol 14 ◽  
pp. 1627-1642 ◽  
Author(s):  
Erik Högfeldt ◽  
Niels Hofman-Bang ◽  
Thor A. Bak ◽  
E. Varde ◽  
Gertrud Westin
Keyword(s):  
Acidity Function ◽  
Hammett Acidity Function ◽  
Ion Activities ◽  
Strong Acids

Hammett acidity function of water-salt solutions of strong acids

1989 ◽  
Vol 38 (11) ◽  
pp. 2234-2237 ◽  
Author(s):  
S. G. Sysoeva ◽  
I. S. Kislina ◽  
M. I. Vinnik
Keyword(s):  
Acidity Function ◽  
Salt Solutions ◽  
Hammett Acidity Function ◽  
Water Salt ◽  
Strong Acids

Preparation and Characterization of a Novel Room Temperature Dicationic Ionic Liquid and its Application in the Synthesis of Xanthenediones Under Solvent-Free Conditions

2018 ◽  
Vol 21 (8) ◽  
pp. 602-608 ◽  
Author(s):  
Zainab Ehsani-Nasab ◽  
Ali Ezabadi
Keyword(s):  
Ionic Liquid ◽  
Room Temperature ◽  
Reaction Times ◽  
Significant Loss ◽  
Solvent Free ◽  
Acidity Function ◽  
Efficient Catalyst ◽  
Solvent Free Conditions ◽  
Hammett Acidity Function ◽  
Dicationic Ionic Liquid

Aim and Objective: In the present work, 1, 1’-sulfinyldiethylammonium bis (hydrogen sulfate) as a novel room temperature dicationic ionic liquid was synthesized and used as a catalyst for xanthenediones synthesis. Material and Method: The dicationic ionic liquid has been synthesized using ethylamine and thionyl chloride as precursors. Then, by the reaction of [(EtNH2)2SO]Cl2 with H2SO4, [(EtNH2)2SO][HSO4]2 was prepared and after that, it was characterized by FT-IR, 1H NMR, 13C NMR as well as Hammett acidity function. This dicationic ionic liquid was used as a catalyst for the synthesis of xanthenediones via condensation of structurally diverse aldehydes and dimedone under solvent-free conditions. The progress of the reaction was monitored by thin layer chromatography (ethyl acetate/n-hexane = 3/7). Results: An efficient solvent-free method for the synthesis of xanthenediones has been developed in the presence of [(EtNH2)2SO][HSO4]2 as a powerful catalyst with high to excellent yields, and short reaction times. Additionally, recycling studies have demonstrated that the dicationic ionic liquid can be readily recovered and reused at least four times without significant loss of its catalytic activity. Conclusion: This new dicationic ionic liquid can act as a highly efficient catalyst for xanthenediones synthesis under solvent-free conditions.

scholarly journals The Activating Effect of Strong Acid for Pd-Catalyzed Directed C–H Activation by Concerted Metalation-Deprotonation Mechanism

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 4083
Author(s):  
Heming Jiang ◽  
Tian-Yu Sun
Keyword(s):  
Activation Energy ◽  
Dft Calculations ◽  
Energy Barrier ◽  
Computational Study ◽  
Strong Acid ◽  
Activation Energy Barrier ◽  
Pd Catalysts ◽  
Acid Ligand ◽  
Strong Acids

A computational study on the origin of the activating effect for Pd-catalyzed directed C–H activation by the concerted metalation-deprotonation (CMD) mechanism is conducted. DFT calculations indicate that strong acids can make Pd catalysts coordinate with directing groups (DGs) of the substrates more strongly and lower the C–H activation energy barrier. For the CMD mechanism, the electrophilicity of the Pd center and the basicity of the corresponding acid ligand for deprotonating the C–H bond are vital to the overall C–H activation energy barrier. Furthermore, this rule might disclose the role of some additives for C–H activation.

IONIZATION OF ORGANIC COMPOUNDS: III. BASICITIES OF PROPIONIC ACID AND PROPIONAMIDE

1962 ◽  
Vol 40 (5) ◽  
pp. 966-975 ◽  
Author(s):  
J. T. Edward ◽  
I. C. Wang
Keyword(s):  
Sulphuric Acid ◽  
Propionic Acid ◽  
Organic Compounds ◽  
Acid Concentration ◽  
Ultraviolet Absorption ◽  
Protonation Constants ◽  
Acidity Function ◽  
Hammett Acidity Function ◽  
Ionization Ratio

Protonation constants (pKBH+) of −6.8 and −0.9 have been determined for propionic acid and propionamide, respectively, from measurements of their ultraviolet absorption in various concentrations of sulphuric acid. The ionization ratio of propionamide and of other amides increases more slowly than the Hammett acidity function, h0, with increase in acid concentration. This may be explained by assuming that in a given concentration of sulphuric acid the protonated amide is more heavily hydrated than the protonated Hammett indicator used to establish the h0 scale for this region of acid concentrations.

scholarly journals Utilization of Kalpataru Flower Extract (Hura crepitans Linn) as an Alternative Acid Base Indicator

2020 ◽  
Vol 9 (3) ◽  
pp. 148-157
Author(s):  
Bayu Riswanto ◽  
Sitti Aminah
Keyword(s):  
Strong Acid ◽  
Weak Acids ◽  
Acid Base ◽  
Flower Extract ◽  
Weak Bases ◽  
Base Solution ◽  
Acid Base Titration ◽  
Hura Crepitans ◽  
Dark Green ◽  
Strong Acids

Kalpataru flower (Hura crepitans Linn) is an anthocyanin-containing plant. This study aims to utilize extract from the kalpataru flower as an alternative acid base indicator and determine the type of acid-base titration suitable for extracting the kalpataru flower indicator. Kalpataru flowers are macerated with methanol solvent for around 2 hours. Kalpataru flower extract was tested as an indicator in acid-base solution, buffer, and compared with phenolphthalein and methyl orange for acid-base titration, namely: strong acids with strong bases, weak acids with strong bases, and weak bases with strong acids. The results obtained in this study were: indicator extract of brownish yellow kalpataru flowers, in strong red acids, in strong bases of dark green, in weak pink acids, and in weak bases in light green. In the buffer, the indicator extract of the kalpataru flower has a range of pH pH 4-5 (pink-colorless) and pH 9-11 (yellowish green-dark green). The indicator of kalpataru flower extract can be used on strong acid titration with strong bases, weak acids with strong bases and weak bases with strong acids. Kalpataru flower extract can be used as an acid-base indicator.

scholarly journals Predictive models for the phase behaviour and solution properties of weak electrolytes: nitric, sulphuric, and carbonic acids

2021 ◽  
Author(s):  
Maximilian Kohns ◽  
Georgia Lazarou ◽  
Spiros Kournopoulos ◽  
Esther Forte ◽  
Felipe A. Perdomo ◽  
...  
Keyword(s):  
Equilibrium Constants ◽  
Ion Pairing ◽  
Ionic Species ◽  
Phase Behaviour ◽  
Solution Properties ◽  
Science And Engineering ◽  
Degree Of Dissociation ◽  
Hydronium Ion ◽  
Weak Electrolytes ◽  
Carbonic Acids

The distribution of ionic species in electrolyte systems is important in many fields of science and engineering, ranging from the study of degradation mechanisms to the design of systems for electrochemical energy storage. Often, other phenomena closely related to ionic speciation, such as ion pairing, clustering and hydrogen bonding, which are difficult to investigate experimentally, are also of interest. Here, we develop an accurate molecular approach, accounting for reactions as well as association and ion pairing, to deliver a predictive framework that helps validate experiment and guides future modelling of speciation phenomena of weak electrolytes. We extend the SAFT-VRE Mie equation of state [D. K. Eriksen et al., Mol. Phys., 2016, 114, 2724–2749] to study aqueous solutions of nitric, sulphuric, and carbonic acids, considering complete and partially dissociated models. In order to incorporate the dissociation equilibria, correlations to experimental data for the relevant thermodynamic equilibrium constants of the dissociation reactions are taken from the literature and are imposed as a boundary condition in the calculations. The models for water, the hydronium ion, and carbon dioxide are treated as transferable and are taken from our previous work. We present new molecular models for nitric acid, and the nitrate, bisulfate, sulfate, and bicarbonate anions. The resulting framework is used to predict a range of phase behaviour and solution properties of the aqueous acids over wide ranges of concentration and temperature, including the degree of dissociation, as well as the activity coefficients of the ionic species, and the activity of water and osmotic coefficient, density, and vapour pressure of the solutions. The SAFT-VRE Mie models obtained in this manner provide a means of elucidating the mechanisms of association and ion pairing in the systems studied, complementing the experimental observations reported in the literature.

scholarly journals Catalytic oxidation of toluene by ozone in the system "acetic anhydride–strong acid"

2021 ◽  
pp. 106-111
Author(s):  
E.V. Potapenko ◽  
◽  
P.Y. Andreev ◽  
I.P. Isayenko ◽  
N.S. Andreeva
Keyword(s):  
Transition Metals ◽  
Acetic Anhydride ◽  
Kinetic Parameters ◽  
Catalytic Oxidation ◽  
Decisive Role ◽  
Strong Acid ◽  
Oxidation Products ◽  
Substrate Conversion ◽  
High Degree ◽  
Strong Acids

The process of catalytic oxidation of toluene by ozone in the solution of a mixture "acetic anhydride–a strong acid" has been studied in the presence of compounds of transition metals. It is shown that the main oxidation products in the system Mn(Ac)2–(СН3СО)2О–Н2SO4 at 200C are benzylacetate and benzylidene diacetate with the yields of 39% and 29%, respectively. In the system Со(Ac)2–(СН3СО)2О–НА, the reaction is accompanied mainly by the formation of benzylidene diacetate (68.0%) and the yield of benzylacetate does not exceed 4.0%. The kinetic parameters of the main stages of the catalytic cycle were investigated. It was found that strong acids play a decisive role in increasing the activity of oxidized forms of the metal. Under the conditions of activation by strong acids, the reaction of methylbenzene with Me3+ occurs with a high degree of substrate conversion. It was found that the reduction of Me3+ in the reaction with the solvent becomes noticeable, along with the oxidation of toluene, with increasing the concentration of strong acids. It was stated that the selective oxidation of toluene under catalysis is initiated by the reaction with an oxidized form of the metal formed by the interaction of ozone with the catalyst.

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