The Henderson-Hasselbalch Equation: Its History and Limitations

The article deals with experimental determination of ionization constants and solubility for the compounds (target products, initial β-lactams, acylating agents and by-products) involved in enzymatic synthesis of some therapeutically used aminopenicillins and aminocephalosporins, namely ampicillin, amoxicillin, cephalexin, cephadroxil, cephaloglycin, cefaclor, cefprozil, cefatrizine. Methodology of investigations and the evaluation of experimental data for the determination of ionization constants and solubility of the different type electrolytes are presented. Applications of the methods based on acid-base potentiometric titration and on determination of solubility-pH dependence of assayed substances are discussed. The original data on ionization constants and solubility of amoxicillin, cefprozil, cefatrizine, cephadroxil and initial β-lactams for production of cefaclor, cefprozil and cefatrizine, as well as solubility of by-product D-(-)-p-hydroxyphenylglycine are presented. Experimentally determined parameters and constants available in the literature for all abovementioned aminopenicillins and aminocephalosporins are collected. These data might be used for choice of the conditions of both processes: the enzymatic synthesis and the isolation of the product from reaction mixture.

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“…Processing the experimental data for calculation of pK (pK = -lgK) by Henderson equation [11] is described in the text.…”

Section: List Of Designationsmentioning

confidence: 99%

Ionization constants and solubility of compounds involved in enzymatic synthesis of aminopenicillins and aminocephalosporins

Kurochkina

Sklyarenko

Satarova

et al. 2011

Bioprocess Biosyst Eng

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“…This type of analysis is expected to give reasonable data for concentrations of 2-11 mM used in this study, with an activity coefficient close to unity. [37,38] The possible error introduced into the pK a value by neglecting the effects of dilution during the NMR titration experiment has been calculated to be <3%.…”

Section: Introductionmentioning

confidence: 99%

NMR determination of pK_a values of indoloquinoline alkaloids

Grycová

Dommisse

Pieters

et al. 2009

Magnetic Reson in Chemistry

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Malaria is one of the most serious global health problems. Isolating new therapeutic agents with potential antimalarial activity from natural sources or preparing such agents either semisynthetically or synthetically is one strategy for solving the problem of resistance constantly evolving to the drugs currently in use. For alkaloids, the acid-base dissociation constant, pK(a), is an important characteristic, thought to be associated with biological activity. In this contribution, pK(a) values for several indoloquinoline alkaloids were determined by using (1)H NMR spectroscopy in a mixture of solvents. The data were recalculated for water solutions using the correction factors reported previously. The structural dependence of the pK(a) values for cryptolepine and its isomers neocryptolepine, isocryptolepine and isoneocryptolepine as well as some substituted neocryptolepine derivatives is discussed.

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“…according to the Henderson-Hasselbalch equation (De Levie 2003). The measurement of a steady ORP around 400 mV/ SHE ( Fig.…”

Section: Chemical Analyses Of Leachatesmentioning

confidence: 99%

Arsenopyrite weathering under conditions of simulated calcareous soil

Lara¹,

Velázquez²,

Vazquez‐Arenas³

et al. 2015

Environ Sci Pollut Res

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Mining activities release arsenopyrite into calcareous soils where it undergoes weathering generating toxic compounds. The research evaluates the environmental impacts of these processes under semi-alkaline carbonated conditions. Electrochemical (cyclic voltammetry, chronoamperometry, EIS), spectroscopic (Raman, XPS), and microscopic (SEM, AFM, TEM) techniques are combined along with chemical analyses of leachates collected from simulated arsenopyrite weathering to comprehensively examine the interfacial mechanisms. Early oxidation stages enhance mineral reactivity through the formation of surface sulfur phases (e.g., S n (2-)/S(0)) with semiconductor properties, leading to oscillatory mineral reactivity. Subsequent steps entail the generation of intermediate siderite (FeCO3)-like, followed by the formation of low-compact mass sub-micro ferric oxyhydroxides (α, γ-FeOOH) with adsorbed arsenic (mainly As(III), and lower amounts of As(V)). In addition, weathering reactions can be influenced by accessible arsenic resulting in the formation of a symplesite (Fe3(AsO4)3)-like compound which is dependent on the amount of accessible arsenic in the system. It is proposed that arsenic release occurs via diffusion across secondary α, γ-FeOOH structures during arsenopyrite weathering. We suggest weathering mechanisms of arsenopyrite in calcareous soil and environmental implications based on experimental data.

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The Henderson-Hasselbalch Equation: Its History and Limitations

Cited by 45 publications

References 8 publications

Ionization constants and solubility of compounds involved in enzymatic synthesis of aminopenicillins and aminocephalosporins

Ionization constants and solubility of compounds involved in enzymatic synthesis of aminopenicillins and aminocephalosporins

NMR determination of pK_a values of indoloquinoline alkaloids

Arsenopyrite weathering under conditions of simulated calcareous soil

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The Henderson-Hasselbalch Equation: Its History and Limitations

Cited by 45 publications

References 8 publications

Ionization constants and solubility of compounds involved in enzymatic synthesis of aminopenicillins and aminocephalosporins

Ionization constants and solubility of compounds involved in enzymatic synthesis of aminopenicillins and aminocephalosporins

NMR determination of pKa values of indoloquinoline alkaloids

Arsenopyrite weathering under conditions of simulated calcareous soil

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Product

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NMR determination of pK_a values of indoloquinoline alkaloids