Potentiometrische Mikrobestimmung von scheinbaren Dissoziationskonstanten in Essigsäure

Wegmann, Dorothée; Simon, W.

doi:10.1002/hlca.19620450324

Cited by 17 publications

(7 citation statements)

References 28 publications

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“…As a check, the • for diphenylamine (pK"h0Ac = 6.22 at 25°C) was also measured by this method. This corresponds well with the value obtained previously by Wegmann and Simon (10) (pK'H0Ac = 6.09 at 25°C).…”

supporting

confidence: 93%

“…The insolubility of azatriptycene and its salts in water precluded the direct measurement of the pKa in this solvent. The measurement was therefore carried out in acetic acid (HOAc) and referred back to the aqueous system through the relationship of Wegmann and Simon (10).…”

mentioning

confidence: 99%

“…Potentiometric titrations of NaOAc and azatriptycene in HOAc with anhydrous HCIO4 in HOAc were carried out at 25°C with a glass electrode and a modified calomel electrode similar to that used by Wegmann and Simon (10). Sample titration curves are shown in Figure 1.…”

mentioning

confidence: 99%

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pKa of azatriptycene

Kreil¹,

Sandel²

1976

J. Chem. Eng. Data

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The pKa of azatriptycene (9H-9,10(1',2')-benzenoacrldine) (4) is measured and found to be 2.1. This value is obtained by potentiometric titration of 4 at 25°with HCI04 In anhydrous HOAc and is related to the aqueous system through the relationship of Wegmann and Simon. The inductive effect of adding benzo-substituents to 1 reduces the basicity an average of 2.8 pK units per substituent.Aryl amines are approximately six orders of magnitude less basic than aliphatic amines. This decrease in basicity is attributed to both resonance and inductive effects. Van der Krogt and Wepster (9,11) have measured the basicities of quinuclidine (1), benzoquinuclidine (2), and dibenzoquinuclidine (3) (pKa's 10.58, 7.79, and 4.46, respectively, at 25°C). Since the nitrogen lone pairs in these compounds are orthogonal to the pi systems, resonance effects are minimal, and the ApKa's of ~3 pK units which Wepster observed are attributed solely to the inductive effects of the phenyl rings. We have now measured the pKa of the final compound in this series, azatriptycene (12) [9H-9,10(1',2')-benzenoacridine] (4), and report the change in basicity for the addition of the third benzo substituent to quinuclidine.

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supporting

confidence: 93%

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confidence: 99%

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pKa of azatriptycene

Kreil¹,

Sandel²

1976

J. Chem. Eng. Data

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“…This approach became the foundation for the calculation of equilibrium constants derived from potentiometric measurements. In spite that in subsequent years researchers such as Shkodin, Karkuzaki and Zadornichaya [2 ± 4] questioned Kolthoff and Bruckenstein, their work gained wider acceptance also due to further contributions by Schwartzenbach and Stenby [5], Tanaka and Nagasuka [6], Wegmann and Simon [7], and recently from Barbosa et al [8,9]. There has been a lesser amount of work since then, dealing with the assessment of thermodynamic equilibrium constants using potentiometric methods, even if there are available commercial glass electrodes for pH and special reference electrodes for this medium.…”

Section: Introductionmentioning

confidence: 93%

Characterization of the Analytical Response of ISFET Sensors for Quantitative and Thermodynamic Assessment in Glacial Acetic Acid

Álvarez-Romero¹,

Rojas-Hernándéz²,

Silva³

et al. 2003

Electroanalysis

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This work presents the results of the studies on the operating characteristics of ISFET sensors, which had a silicon nitride membrane, using glacial acetic acid as solvent. The stability periods found were between five and seven minutes with response time in the range of 50 to 70 seconds. Pyridine was determined quantitatively and the results were compared with those obtained with a commercial glass electrode; the analysis of variance (ANOVA) demonstrated that there were no significant differences for the results from either type of sensor. The Biederman and Sille ¬ n calibration method was applied to the potentiometric system: the linear response range found was 4.3 < pH < 10.4. The ISFET presented different sensitivities for the acid and basic regions, such that with usage the sensitivity increased toward the acetate ion while that for the solvated proton decreased, and so did the reproducibility as well. The initial analytical properties of the sensor are restored upon regeneration of the silicon nitride membrane. The equilibrium constants for the protonated pyridine and diethylamine perchlorates were determined: the values found do not differ statistically in respect to those reported in the literature. Also, it was found that upon regeneration of the selective membrane, the ISFET can be used in aqueous and glacial acetic media.

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“…With the data for the equilibrium constants of different bases, the aforementioned authors validated their theoretical calculations comparing them with experimental data; this kind of analysis became the stepping-stone for the assessment of equilibrium constants starting from potentiometric measurements. Although in subsequent years, some researchers such as Shkodin et al [4,5,6] questioned the work by Kolthoff and Bruckenstein, the latter's fundamental contribution has gradually gained consolidation, thanks to subsequent research by other workers, such as Schwarzenbach and Stenby [7], Tanaka and Nagasuka [8], Wegman and Simon [9], and recently Barbosa et al [10,11].…”

Section: Introductionmentioning

confidence: 95%

Potentiometric determination of equilibrium constants of bases and perchlorates of protonated bases in glacial acetic acid using Superquad

et al. 2003

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The traditional method of calculating equilibrium constants in glacial acetic acid medium was developed by Kolthoff and Bruckenstein in 1957; thenceforth, and even presently, few alternatives have been made available to undertake such studies. This paper presents the results obtained with the use of the program Superquad to assess the equilibrium constants of various bases and their protonated perchlorate salts in glacial acetic media. A model of formation equilibria is proposed and fed into the program, considering the species present during an acid-base titration. The calculations of the equilibrium constants using Superquad for pyridine and diethylamine are statistically in agreement with those reported in the literature, (for pyridine: pK(B)=5.98+/-0.02, pK( PyHClO4)=5.47+/-0.02 and for diethylamine pK(B)=5.52+/-0.04, pK( DietHClO4)=4.52+/-0.07). With the use of Superquad, the values found for the aniline were pK(B)=6.95+/-0.06 and pK( AnilHClO4)=4.89+/-0.06.

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Potentiometrische Mikrobestimmung von scheinbaren Dissoziationskonstanten in Essigsäure

Cited by 17 publications

References 28 publications

pKa of azatriptycene

pKa of azatriptycene

Characterization of the Analytical Response of ISFET Sensors for Quantitative and Thermodynamic Assessment in Glacial Acetic Acid

Potentiometric determination of equilibrium constants of bases and perchlorates of protonated bases in glacial acetic acid using Superquad

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