An acidity function in ethanol – sulfuric acid based on the protonation of diphenylamines

1967 ◽  
Vol 45 (9) ◽  
pp. 903-910 ◽  
Author(s):  
Douglas Dolman ◽  
Ross Stewart
Keyword(s):  
Sulfuric Acid ◽  
Nitro Group ◽  
Strong Interaction ◽  
Acidic Solution ◽  
Sulfuric Acid Concentration ◽  
Substituent Effects ◽  
Solvent System ◽  
Acidity Function ◽  
Substituent Constants ◽  
Hammett Σ Constants

A Hammett H0 acidity function based on the protonation of 17 diphenylamines in 20 volume % ethanol – aqueous sulfuric acid has been established. The H0 value for the most acidic solution studied (11.2 M sulfuric acid) is −6.97. This acidity function differs from that based on the protonation of azobenzenes in the same solvent system; the latter diverges to more negative H0 values as the sulfuric acid concentration increases.The [Formula: see text] values for the protonation of the diphenylamines vary from +1.36 for 4-methoxy-diphenylamine to − 6.21 for 4,4′-dinitrodiphenylamine. A plot of [Formula: see text] versus the Hammett σ constants for five monosubstituted diphenylamines yields a ρ value of +3.36. The [Formula: see text] values for 4-methoxy-, 4-methyl-, 4-methylsulfonyl-, and 4-nitro-diphenylamine are all less (more negative) than expected from the Hammett substituent constants. The substituent effects on the basicities of aniline and diphenylamine are the same.The basicities of several nitro-substituted diphenylamines appear to vary regularly, and do not reflect the presence of a strong interaction between the nitro group and sulfuric acid.

scholarly journals Substituent effects of nitro group in cyclic compounds

2020 ◽  
Vol 32 (1) ◽  
pp. 179-203 ◽  
Author(s):  
Anna Jezuita ◽  
Krzysztof Ejsmont ◽  
Halina Szatylowicz
Keyword(s):  
Nitro Group ◽  
System Analysis ◽  
Inductive Effect ◽  
Resonance Effect ◽  
Substituent Effects ◽  
Electron Delocalization ◽  
High Electron ◽  
Aromatic Character ◽  
Substituent Constants ◽  
Cyclic Compounds

AbstractNumerous studies on nitro group properties are associated with its high electron-withdrawing ability, by means of both resonance and inductive effect. The substituent effect of the nitro group may be well described using either traditional substituent constants or characteristics based on quantum chemistry, i.e., cSAR, SESE, and pEDA/sEDA models. Interestingly, the cSAR descriptor allows to describe the electron-attracting properties of the nitro group regardless of the position and the type of system. Analysis of classical and reverse substituent effects of the nitro group in various systems indicates strong pi-electron interactions with electron-donating substituents due to the resonance effect. This significantly affects the pi-electron delocalization of the aromatic ring decreasing the aromatic character, evidenced clearly by HOMA values. Use of the pEDA/sEDA model allows to measure the population of electrons transferred from the ring to the nitro group.

Synthesis and cyclization kinetics and mechanism of 1-(2-ethoxycarbonylphenyl)-3-aryltriazenes. Kinetic acidity function of sodium methoxide in methanol

1990 ◽  
Vol 55 (10) ◽  
pp. 2468-2474 ◽  
Author(s):  
Oldřich Pytela ◽  
Vladimír Dlouhý
Keyword(s):  
Rate Constants ◽  
Sodium Methoxide ◽  
Substituent Effects ◽  
Acidity Function ◽  
Subsequent Reaction ◽  
Limiting Step ◽  
Kinetic Acidity ◽  
Substituent Constants ◽  
Catalytic Rate ◽  
Cyclization Kinetics

Eight 1-(2-ethoxycarbonylphenyl)-3-aryltriazenes have been synthetized and the rate constants of their sodium-methoxide-catalyzed cyclization have been measured in methanol at 25 °C. The experimental rate constants kobs have been adopted to construct the kinetic acidity function HKM which has been shown to be identical with the -log[CH3O-] values. Two mathematical procedures have been used to determine the catalytic rate constants and their dependence on the Hammett substituent constants. A closer dependence is obtained with the σ values than with the σp- values. The ρ value found (0.3) indicates a compensation of the substituent effects upon the dissociation of the starting triazene and upon the subsequent reaction of the conjugated base. Out of the two mechanistic alternatives - E1cB and BAc2 - the latter appears to be more probable, the splitting of tetrahedral intermediate being its limiting step.

Substituent effects on selectivity of coupled oxidation of iron tetraphenylporphyrins

2015 ◽  
Vol 19 (05) ◽  
pp. 726-733 ◽  
Author(s):  
Kazuhisa Kakeya ◽  
Atsuko Shimizu ◽  
Kenta Akasaka ◽  
Tadashi Mizutani
Keyword(s):  
Nitro Group ◽  
Oxidation Rate ◽  
Substituent Effects ◽  
Para Position ◽  
Positive Slope ◽  
Substituent Constant ◽  
Meso Position ◽  
Substituent Constants

Coupled oxidation of iron tetraphenylporphyrins bearing either a OMe , Me , F , Cl , COOMe , CF 3 or CN group in the para-position of the phenyl groups gave tetraarylbiladien-ab-1-one and triarylbilindione. The ratios of the yields of the former to those of the latter were linearly correlated with the Hammett substituent constants σp+, with a positive slope (Δρ = 0.64). The Hammett plot of the oxidation rate vs. the substituent constant σp also showed a positive slope (ρ = 0.30). These substituent effects suggest that a nucleophilic step is included in the formation of bilindione. Coupled oxidation of an A3B type tetraarylporphyrin having an electron withdrawing nitro group in one of the phenyl groups indicated that the oxidation leading to biladienone occurred rather statistically in any of the meso-positions, while the oxidation leading to bilindione occurred preferentially in the meso-position bearing the 4-nitrophenyl group.

Strongly basic systems. VIII. The H− function for dimethyl sulfoxide – water – tetramethylammonium hydroxide

1967 ◽  
Vol 45 (9) ◽  
pp. 911-924 ◽  
Author(s):  
Douglas Dolman ◽  
Ross Stewart
Keyword(s):  
Dimethyl Sulfoxide ◽  
Tetramethylammonium Hydroxide ◽  
Strengthening Effect ◽  
Acidity Function ◽  
Substituent Constant ◽  
Substituted Anilines ◽  
Hydroxide Ion ◽  
Substituent Constants ◽  
Hammett Σ Constants ◽  
Increased Activity

An H− acidity function based on the ionization of 24 substituted anilines and diphenylamines has been established in the system dimethyl sulfoxide – water – tetramethylammonium hydroxide. The H− of a 0.011 M solution of tetramethylammonium hydroxide ranges from 12 in water to 26.2 in 99.6 mole % dimethyl sulfoxide – water, an increase in basicity of 14 powers of 10. The increase in basicity is due to the increased activity of the hydroxide ion brought about by the reduction in its solvation in the poor anion-solvating solvent dimethyl sulfoxide, and indicates the extensive solvation enjoyed by the hydroxide ion in water.The pKHA values of the indicator acids vary from 13.9 for 2,4-dinitrodiphenylamine to 25.6 for 3-chloroaniline. From a plot of log KHA versus the Hammett substituent constants (σ) for six monosubstituted diphenylamines, a ρ value of 4.07 is found. Similar results are obtained for the anilines. The acidities of all the substituted diphenylamines do not follow the above-mentioned correlation with the Hammett σ constants; the pKHA values of 4-amino-, 4-methoxy-, 4-methylsulfonyl-, and 4-nitro-diphenylamine are all less than expected from the Hammett σ constants for the substituents in these compounds. The 4-nitro substituent exerts a particularly large acid-strengthening effect on the acidities of aniline and diphenylamine, the decreases in pKHA being approximately 8.4 and 6.8 pK units, respectively. An exalted substituent constant of +1.65 for p-NO2 is needed to account for the acidity of p-nitro-diphenylamine.

An Acidity Function for the Solvent System Consisting of 20 Vol.% Ethanol and 80 Vol.% Sulfuric Acid-Water Mixtures1

1959 ◽  
Vol 81 (13) ◽  
pp. 3274-3278 ◽  
Author(s):  
Si-Jung Yeh ◽  
H. H. Jaffé
Keyword(s):  
Sulfuric Acid ◽  
Solvent System ◽  
Acid Water ◽  
Acidity Function

Protonation of conjugated carbonyl groups in sulfuric acid solutions. II. Protonation and basicity of α,β-unsaturated alicyclic ketones

1969 ◽  
Vol 47 (12) ◽  
pp. 2263-2270 ◽  
Author(s):  
R. I. Zalewski ◽  
G. E. Dunn
Keyword(s):  
Sulfuric Acid ◽  
Substituent Effects ◽  
Acidity Function ◽  
Acid Solutions ◽  
Carbonyl Groups ◽  
Resonance Effects ◽  
Unit Slope ◽  
Straight Lines ◽  
Sulfuric Acid Solutions

The protonation of 14 α,β-unsaturated alicyclic ketones, B, by sulfuric acid leads to values of log [B]/[BH+] which, when plotted against the amide acidity function, HA, give straight lines of unit slope. The [Formula: see text] values thus obtained show substituent effects which are additive and can be interpreted in terms of polar and resonance effects.

Substituent effects in 1,3-indanediones

1982 ◽  
Vol 47 (5) ◽  
pp. 1486-1493 ◽  
Author(s):  
Alexander Perjéssy
Keyword(s):  
Substituent Effects ◽  
Empirical Equations ◽  
Substituent Constants ◽  
Complex Structural

The carbonyl stretching frequencies correlate well with substituent constants in a series of 166 1,3-indanediones using improved and extended Seth-Paul-Van Duyse equation. Transmissive factors and group electronegativities have been used to find empirical equations for calculation of substituent constants of more complex structural fragments.

Kinetic Study of Hydrolysis of Benzoates. Part XXVI. Variation of the Substituent Effect with Solvent in Alkaline Hydrolysis of Substituted Alkyl Benzoates

2006 ◽  
Vol 71 (11-12) ◽  
pp. 1557-1570 ◽  
Author(s):  
Vilve Nummert ◽  
Mare Piirsalu ◽  
Ilmar A. Koppel
Keyword(s):  
Kinetic Study ◽  
Alkaline Hydrolysis ◽  
Rate Constants ◽  
Substituent Effect ◽  
Substituent Effects ◽  
Alkyl Substituent ◽  
Solvent Parameters ◽  
Substituent Constants ◽  
Hydrolysis Of ◽  
Main Factor

The second-order rate constants k2 (dm3 mol-1 s-1) for the alkaline hydrolysis of substituted alkyl benzoates C6H5CO2R have been measured spectrophotometrically in aqueous 0.5 M Bu4NBr at 50 and 25 °C (R = CH3, CH2Cl, CH2CN, CH2C≡CH, CH2C6H5, CH2CH2Cl, CH2CH2OCH3, CH2CH3) and in aqueous 5.3 M NaClO4 at 25 °C (R = CH3, CH2Cl, CH2CN, CH2C≡CH). The dependence of the alkyl substituent effects on different solvent parameters was studied using the following equations:      ∆ log k = c0 + c1σI + c2EsB + c3∆E + c4∆Y + c5∆P + c6∆EσI + c7∆YσI + c8∆PσI     ∆ log k = c0 + c1σ* + c2EsB + c3∆E + c4∆Y + c5∆P + c6∆Eσ* + c7∆Yσ* + c8∆Pσ* .  ∆ log k = log kR - log kCH3. σI and σ* are the Taft inductive and polar substituent constants. E, Y and P are the solvent electrophilicity, polarity and polarizability parameters, respectively. In the data treatment ∆E = ES - EH2O , ∆Y = YS - YH2O , ∆P = PS - PH2O were used. The solvent electrophilicity, E, was found to be the main factor responsible for changes in alkyl substituent effects with medium. When σI constants were used, variation of the polar term of alkyl substituents with the solvent electrophilicity E was found to be similar to that observed earlier for meta and para substituents, but twice less when σ* constants were used. The steric term for alkyl substituents was approximately independent of the solvent parameters.

scholarly journals Achieving highly efficient and selective cesium extraction using 1,3-di-octyloxycalix[4]arene-crown-6 in n-octanol based solvent system: experimental and DFT investigation

RSC Advances ◽  
2021 ◽  
Vol 11 (35) ◽  
pp. 21323-21331
Author(s):  
Kankan Patra ◽  
Biswajit Sadhu ◽  
Arijit Sengupta ◽  
C. B. Patil ◽  
R. K. Mishra ◽  
...  
Keyword(s):  
Fission Product ◽  
Acidic Solution ◽  
Solvent System ◽  
Selective Extraction ◽  
Separation Scheme ◽  
Highly Efficient ◽  
Aqueous Acidic Solution

Separation scheme was developed for selective extraction of long-lived fission product 137Cs using substituted calix crown 6 ether from aqueous acidic solution.

scholarly journals Effective Recovery Process of Copper from Waste Printed Circuit Boards Utilizing Recycling of Leachate

JOM ◽  
2020 ◽  
Author(s):  
Joona Rajahalme ◽  
Siiri Perämäki ◽  
Roshan Budhathoki ◽  
Ari Väisänen
Keyword(s):  
Hydrogen Peroxide ◽  
Sulfuric Acid ◽  
Printed Circuit Boards ◽  
Sulfuric Acid Concentration ◽  
Recovery Process ◽  
Copper Recovery ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Waste Printed Circuit Boards ◽  
Acid Consumption

AbstractThis study presents an optimized leaching and electrowinning process for the recovery of copper from waste printed circuit boards including studies of chemical consumption and recirculation of leachate. Optimization of leaching was performed using response surface methodology in diluted sulfuric acid and hydrogen peroxide media. Optimum leaching conditions for copper were found by using 3.6 mol L−1 sulfuric acid, 6 vol.% hydrogen peroxide, pulp density of 75 g L−1 with 186 min leaching time at 20°C resulting in complete leaching of copper followed by over 92% recovery and purity of 99.9% in the electrowinning. Study of chemical consumption showed total decomposition of hydrogen peroxide during leaching, while changes in sulfuric acid concentration were minor. During recirculation of the leachate with up to 5 cycles, copper recovery and product purity remained at high levels while acid consumption was reduced by 60%.

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