Acidic Dissociation Constants of Alcoholic Hydroxyls of Hydroxycarboxylic Acids: Tartaric Acid

Beck, M. T.; Csiszár, B.; Szarvas, P.

doi:10.1038/188846a0

Cited by 21 publications

(7 citation statements)

References 3 publications

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“…As pH increased to 9.0 from 6.0, brushite can be partially deprotonated due to approaching the isoelectric point of brushite (6.1) . The dianionic species of two −COOH groups in a TA molecule is present in solutions, and alcoholic −OH groups do not dissociate. , In addition, no dissociation of interfacial water has been observed during the geometrical optimizations; the DFT calculations in this work only concern the adsorption of dicarboxylic acid on the preferable [1̅01̅] Cc steps. The predicted deprotonated sites on the [1̅01̅] Cc steps can be from H 2 O molecules, because H 2 O molecules are on the outermost surfaces and the bulk protons of HPO 4 – ions are along the [1̅01̅] Cc directions (Figure B).…”

Section: Resultsmentioning

confidence: 99%

“…After further increasing the pH to 9.0, TA caused intense dissolution on the brushite (010) surface with the increase of the pit density (Figure 3C and C′). Because the alcoholic −OH groups of TA and MA did not dissociate even at pH 9.0, 41 dissolution was enhanced only by deprotonated mineral interfaces. However, so far, we have not obtained the sight of the overall dissolution process of the deprotonated brushite (010) face in the presence of hydroxy-dicarboxylic acids by parametrized kinetic Monte Carlo simulation or ab initio molecular dynamics simulation because the piece of work is very computationally demanding.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Role of Alcoholic Hydroxyls of Dicarboxylic Acids in Regulating Nanoscale Dissolution Kinetics of Dicalcium Phosphate Dihydrate

Qin

Wang

2017

ACS Sustainable Chem. Eng.

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Due to the potential shortage of phosphate (P) rock resources and a faster growth in demand for phosphate fertilizers, unraveling the kinetics of calcium phosphate (Ca–P) crystallization and dissolution is important for understanding the P mobility and bioavailability. Plants have developed different strategies, such as carboxylic acid exudation into the rhizosphere, to cope with low P bioavailability through dissolution of sparingly soluble Ca–P minerals. However, the dissolution kinetics may be more complicated in the presence of both carboxylate and hydroxyl groups in organic acids. Here in situ atomic force microscopy (AFM) is used to directly observe the kinetics of nanoscale dissolution on the (010) surface of dicalcium phosphate dihydrate (brushite, CaHPO4·2H2O) in the presence of succinic acid (SA, 0 alcoholic hydroxyl (−OH)), malic acid (MA, 1 −OH), and tartaric acid (TA, 2 −OH), respectively, over a broad concentration range. We demonstrate that the role of dicarboxylic acids varies with the number of alcoholic hydroxyls and that fully deprotonated hydroxy-dicarboxylic acids play a critical role in controlling the dissolution rate of steps and morphology modification of etch pits. Direct AFM imaging shows that only TA can adsorb along specific directions of the [1̅01̅] Cc steps on the brushite (010) surface at pH ≥ 6 to induce the formation of trapezium-shaped etch pits. This depends on specific molecular recognition and stereochemical conformity between hydroxyl-carboxyl of TA and atomic [1̅01̅] Cc steps by molecular modeling using density functional theory. The effectiveness of alcoholic hydroxyls can be enhanced by deprotonated brushite interfaces with the increase of the solution pH. This combined AFM and molecular modeling study may provide microscopic insights into understanding P mobilization by dissolution in soils.

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Section: Resultsmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

Role of Alcoholic Hydroxyls of Dicarboxylic Acids in Regulating Nanoscale Dissolution Kinetics of Dicalcium Phosphate Dihydrate

Qin

Wang

2017

ACS Sustainable Chem. Eng.

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“…To the best of our knowledge, the only attempt in this respect was made by Beck et al 16 From polarimetric measurements, they estimated the pK 3 and pK 4 values to be 13.94 and 15.60 in NaOH, and 13.84 and 15.50 in KOH, respectively.…”

Section: Introductionmentioning

confidence: 99%

Calcium l-tartrate complex formation in neutral and in hyperalkaline aqueous solutions

et al. 2016

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The complex formation reaction between the l-tartrate (Tar) and calcium ions taking place in neutral and in hyperalkaline (pH > 13) aqueous solutions has been investigated. It was demonstrated that upon NaOH addition the solubility of the CaTar precipitate significantly increases. Conductometric and freezing point depression measurements further confirmed that in this process water soluble species are formed as a result of a reaction between the CaTar and the hydroxide ion (or, conversely, between Ca(OH) and the Tar ion). C NMR spectroscopic measurements yielded the value of pK = 15.4 ± 0.2 for the proton dissociation of one of the alcoholic OH groups of Tar (at 25.0 °C and 4 M Na(Cl) ionic strength). Upon addition of calcium ions to an alkaline Tar solution, the H NMR signal gradually broadened and theC-satellite peaks split to two components, which also indicate complexation. From H/Pt potentiometric titrations performed with solutions in the 13.6 ≤ pH ≤ 14.4 range, it was observed, that this complex formation is accompanied by a hydroxide ion consuming process. The titration curves can be best described via assuming the formation of the CaTarH (lg β = -11.2 ± 0.1) and CaTarH (lg β = -25.3 ± 0.1) complexes. In hyperalkaline solutions, these two species account for more than 90-99% of the calcium ions present and the contribution of the other reasonable and well-established calcium-containing solution species is rather small. The possible structures of the above complexes have been modeled via ab initio calculations. The stoichiometries are consistent both with species containing coordinated alcoholate group(s) and with mixed Ca(ii)-hydroxo-tartrato complexes. From the data available at present, both types of structures can be considered as chemically reasonable.

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“…Deposition from alkaline solution is generally made possible by ligands forming soluble complexes with metal ions. Hydroxycarboxylic acids form very stable complexes with metal ions where both the carboxylic and the alcoholic hydroxyl groups take part in complex formation [70]. When these acids are liberated from the complexes with the metal ion upon electrochemical deposition, the hydroxyl groups are reprotonated again because of the small dissociation constants of these acids.…”

Section: Organic and Medicinal Chemistry International Journalmentioning

confidence: 99%

Electrochemical Synthesis of Iron Oxide Nanoparticles for Biomedical Application

Sequeira¹

2018

OMCIJ

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Acidic Dissociation Constants of Alcoholic Hydroxyls of Hydroxycarboxylic Acids: Tartaric Acid

Cited by 21 publications

References 3 publications

Role of Alcoholic Hydroxyls of Dicarboxylic Acids in Regulating Nanoscale Dissolution Kinetics of Dicalcium Phosphate Dihydrate

Role of Alcoholic Hydroxyls of Dicarboxylic Acids in Regulating Nanoscale Dissolution Kinetics of Dicalcium Phosphate Dihydrate

Calcium l-tartrate complex formation in neutral and in hyperalkaline aqueous solutions

Electrochemical Synthesis of Iron Oxide Nanoparticles for Biomedical Application

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