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Journal ArticleDOI

pKa Values of Some Piperazines at (298, 303, 313, and 323) K

Farhad Khalili, +2 more
- 15 Jul 2009 - 
- Vol. 54, Iss: 10, pp 2914-2917
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TLDR
In this paper, the dissociation constants of six cyclic diamines were calculated using the potentiometric titration method at (298, 303, 313, and 323) K. The pKa values of piperazine were compared with published data to validate the procedure used.
Abstract
The dissociation constants of the conjugate acids of six cyclic diamines [piperazine, 1-methylpiperazine, 2-methylpiperazine, 1-ethylpiperazine, 1-(2-hydroxyethyl)piperazine, and 1,4-dimethylpiperazine] were calculated using the potentiometric titration method at (298, 303, 313, and 323) K. The pKa values of piperazine were compared with published data to validate the procedure used. The thermodynamic quantities (ΔH° and ΔS°) for the dissociation processes were determined using the van’t Hoff equation. A trend is proposed related to the variation of the pKa with the addition of different radical groups to the base piperazine molecule.

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Citations
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Journal ArticleDOI

Assessing the influence of different cation chemistries on ionic conductivity and alkaline stability of anion exchange membranes

TL;DR: In this paper, polysulfone (PSF) backbones were functionalized with reactive chloromethyl groups for preparing thin film anion exchange membranes (AEMs) with fixed benzyl quaternary cations.
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Dissociation Constants (pKa) of Tertiary and Cyclic Amines: Structural and Temperature Dependences

TL;DR: In this article, the dissociation constants of 14 amines were measured over a temperature range between 293.15 and 333.15 K using the potentiometric titration method and the change in standard state thermodynamic properties was derived from the van't Hoff equation.
Journal ArticleDOI

Kinetics of carbon dioxide (CO2) with ethylenediamine, 3-amino-1-propanol in methanol and ethanol, and with 1-dimethylamino-2-propanol and 3-dimethylamino-1-propanol in water using stopped-flow technique

TL;DR: Pseudo first order rate constants of homogeneous reactions of carbon dioxide (CO 2 ) with primary amines, ethylenediamine (EDA) and 3-amino-1-propanol (3AP), in methanol and ethanol in the concentration range of 20 −120 m −3, were measured using a stopped-flow apparatus in a temperature range of 293 −313 K as mentioned in this paper.
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Influence of the structure of polyfluorinated alcohols on Brønsted acidity/hydrogen-bond donor ability and consequences on the promoter effect.

TL;DR: Comparison of the effects of fluorinated alcohols as promoting solvents in three reactions is reported, and the positive correlation between rate constants and H-bonding donation ability for sulfide oxidation and imino Diels-Alder reaction brings to light the role of this property.
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NBD-based synthetic probes for sensing small molecules and proteins: design, sensing mechanisms and biological applications

TL;DR: A comprehensive review of NBD-based synthetic probes for biomolecular sensing can be found in this paper, where the authors discuss the sensing mechanisms and selectivity of the probes, the design strategies for multi-reactable multi-quenching probes, and the associated biological applications of these important constructs.
References
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Journal ArticleDOI

Individual Activity Coefficients of Ions in Aqueous Solutions

TL;DR: A revised and extended table of ionic activity coefficients, which has largely been computed by independent means, taking into consideration the diameter of the hydrated ions,* as estimated by various methods, is presented in this article.
Journal ArticleDOI

On the kinetics between co2 and alkanolamines both in aqueous and non-aqueous solutions. an overview

TL;DR: In this paper, an overview is presented of the mechanisms that have been proposed in literature and the kinetic data for the various reactions are critically evaluated, along with the applicability and restrictions are discussed along with perspectives.
Journal ArticleDOI

A study on the reaction between CO2 and alkanolamines in aqueous solutions

TL;DR: The results for DEA and DIPA were analyzed by means of a zwitterion-mechanism which was derived from the mechanism originally proposed by Danckwerts as mentioned in this paper.
Journal ArticleDOI

Absorption of carbon dioxide in aqueous piperazine/methyldiethanolamine

TL;DR: In this article, carbon dioxide absorption in 0.6 M piperazine (PZ)/4 M methyldiethanolamine (MDEA) was measured in a wetted wall contactor.
Journal ArticleDOI

Carbon dioxide absorption with aqueous potassium carbonate promoted by piperazine

TL;DR: In this article, the authors presented thermodynamic and kinetic data for aqueous potassium carbonate promoted by piperazine, used as an additive in 20 − 30 wt % potassium carbonates, in a wetted-wall column using a concentration of 06 m at 40 − 80°C.
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What is the pka value of 2 ethylpyridine?

The provided paper does not mention the pKa value of 2-ethylpyridine. The paper is about the pKa values of some piperazines and their thermodynamic properties.