Calibration of the Glass Electrode in Acetonitrile. Shape of Potentiometric Titration Curves. Dissociation Constant of Picric Acid<sup>1</sup>

Kolthoff, I. M.; Chantooni, M. K.

doi:10.1021/ja00948a004

Cited by 181 publications

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“…Glass electrodes were calibrated with picric-acid/n-tetrabutyl-ammonium-picrate buffers at five concentration ratios offered by Chantooni and Kolthoff [9]. The halogeno-aniline samples were titrated with perchloricacid titrant in acetonitrile.…”

Section: Resultsmentioning

confidence: 99%

The Electrooxidation of Halogeno‐Anilines at Microelectrodes in Acetonitrile Solution

2003

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The electrochemical oxidation of 4-chloro-, 2,4-dichloro-, 2,4,6-trichloro-anilines and 4-bromo-, 2,4-dibromo-, 2,4,6-tribromo-anilines and 4-iodo-aniline were investigated in unbuffered acetonitrile solution. The main reaction at the electrooxidation of these compounds is the dimerization which is accompanied by release of the p-substituent halide and formation of protons. To complete the so far achieved results by the apparent electron exchange number (n app ) determination in the voltammetric time scale have been attempted. These measurements were carried out with the aim, to have a clearer picture on the n app influencing role of the following complicating factors: The rejected halogenides in MeCN solvent at lower potential values as the substrates can be oxidized to the corresponding halogens, and these halogens except the iodine substitute the substrate which takes place even in the voltammetric time scale by increasing the n app value characteristic for the dimerization only. The measurable n app values are influenced by the protons produced at the oxidation as well, in the opposite direction. The explanation for the latter is, that the solvent is aprotic, therefore the differently basic primary amino groups of the diffusing substrate molecules binding partly the protons and in this way voltammetrically inactive substrate species are formed. This reaction is a typical equilibrium type and this inactivation effect decrease the measurable n app value. This effect depends on the quality and number of halogene substituent at a given substrate because these affect the protonation constant of the substrate. Therefore the protonation constants of the substrates had to be determined. In the knowledge of these quantitative data the explanation of the trends in the n app values measured in the voltammetric time scale is attempted. The mechanistic study of the dimerization reaction of these substrates is in progress in our laboratory.

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Section: Resultsmentioning

confidence: 99%

The Electrooxidation of Halogeno‐Anilines at Microelectrodes in Acetonitrile Solution

2003

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“…The theoretical justification for the use of above buffer system has been given previously (7). A pKa = 11.0 for picric acid was used (9). The calibration was performed with five buffers of different ratios and was repeated several times during the course of the study.…”

Section: Resultsmentioning

confidence: 99%

Basicity of substituted 2-phenyl-1,1,3,3- tetramethylguanidines and other bases in acetonitrile solvent

Leffek¹,

Pruszyński²,

Thanapaalasingham³

1989

Can. J. Chem.

108

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A series of 30 phenyl substituted derivatives of 2-phenyl-l,l,3,3-tetramethylguanidine was synthesized and the pKa value of each was measured in acetonitrile using a conventional, general purpose glass electrode. The slope of the Hammett relationship, for the para and meta substituted compounds, p = 2.18 + 0.16, is significantly lower than p = 2.85 * 0.06 found for anilines in water, even though the phenyl ring is attached directly to the basic centre in both cases. The influence of electronic and steric effects on the basicity of the compounds is discussed. The solvent effect on the basicity is also discussed, by comparison of the pKa values in acetonitrile and water. The mean value of Ap~tN-H20 = 8.1 + 0.5 is slightly higher than the value previously observed for ammonia and aliphatic amines, A p~p -H 2 0 = 7.5 * 0. On a synthCtisC une skrie de 30 phtnyl-2 tttramCthyl-1,1,3,3 guanidines substitutes sur le noyau phCnyle et, utilisant une electrode de verre conventionnelle d'usage general, on a mesure les valeurs de leur pK, dans llacCtonitrile. Lapente de la relation de Harnmett, pour les composCs substituks en mPta et en para, p = 2,18 0,16, est beaucoup plus faible que la valeur de p = 2,85 2 0,06 qui a kt6 observee pour les anilines dans l'eau, m&me si le noyau phtnyle est attache directement au centre basique dans chacun des cas. On discute de I'influence des effets sttriques et electroniques sur la basicit6 des composCs. En se basant sur une comparaison des valeurs des pKa dans l'acttonitrile et dans l'eau, on discute aussi de I'effet du solvant sur la basicit&. La

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“…Picrate ion was selected because its 2,6-dinitro groups sterically hinder its capacity for competitive nucleophilic behavior. Building on our exploratory studies on the base strengths of amines in nonprotolytic solvents [11], extensive elegant research on acid-base reactions in acetonitrile solution by the groups of Kolthoff [12][13][14][15] and Coetzee [16] in the 1960s led to the evaluation of the dissociation constants of picric acid and of amine salts in acetonitrile. These data were essential for interpreting our results.…”

Section: Open Accessmentioning

confidence: 99%

Kinetics of Model Reactions for Interfacial Polymerization

et al. 2012

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Abstract:To model the rates of interfacial polycondensations, the rates of reaction of benzoyl chloride and methyl chloroformate with various aliphatic monoamines in acetonitrile were determined at 25 °C. Buffering with picric acid slowed these extremely fast reactions so the rate constants could be determined from the rate of disappearance of picrate ion. The rates of the amine reactions correlated linearly with their Swain-Scott nucleophilicities.

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Calibration of the Glass Electrode in Acetonitrile. Shape of Potentiometric Titration Curves. Dissociation Constant of Picric Acid¹

Cited by 181 publications

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The Electrooxidation of Halogeno‐Anilines at Microelectrodes in Acetonitrile Solution

The Electrooxidation of Halogeno‐Anilines at Microelectrodes in Acetonitrile Solution

Basicity of substituted 2-phenyl-1,1,3,3- tetramethylguanidines and other bases in acetonitrile solvent

Kinetics of Model Reactions for Interfacial Polymerization

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Calibration of the Glass Electrode in Acetonitrile. Shape of Potentiometric Titration Curves. Dissociation Constant of Picric Acid1

Cited by 181 publications

References 0 publications

The Electrooxidation of Halogeno‐Anilines at Microelectrodes in Acetonitrile Solution

The Electrooxidation of Halogeno‐Anilines at Microelectrodes in Acetonitrile Solution

Basicity of substituted 2-phenyl-1,1,3,3- tetramethylguanidines and other bases in acetonitrile solvent

Kinetics of Model Reactions for Interfacial Polymerization

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Calibration of the Glass Electrode in Acetonitrile. Shape of Potentiometric Titration Curves. Dissociation Constant of Picric Acid¹