Thermodynamic solvation of a series of homologous α-amino acids in non-aqueous mixture of ethylene-glycol and N,N-dimethyl formamide

Mahali, Kalachand; Roy, Sanϳay; Dolui, Bijoy Krishna

doi:10.4236/jbpc.2011.23022

Cited by 45 publications

(37 citation statements)

References 15 publications

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“…Moreover, our main concern in the current study is to determine and characterize the total transfer Gibbs energy (DG 0 t ðiÞ) in such binary solvent mixtures; therefore, we also have assumed here that the contribution of activity coefficient is negligible [11,12,15,17,[19][20][21][22][23][24]44]. DG 0 t ðiÞ is also related as DG 0 t ðiÞ ¼ DG 0 s ðiÞ À DG 0 R ðiÞ, where DG 0 t ðiÞ, DG 0 s ðiÞ and DG 0 R ðiÞ are the Gibbs energies of the amino acid solutions in co-solvent (aqueous ME) and reference solvent, water, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…There are several methods [38][39][40][41][42][43] for the determination of the activity coefficients that involve various theoretical aspects and assumptions. But for simplicity, in many earlier studies the activity coefficient was assumed to be unity [11,12,15,17,[19][20][21][22][23][24]44] during the determination of the Gibbs energy of several amino acids in solution.…”

Section: Resultsmentioning

confidence: 99%

“…A known mass (of about 0.2-0.3 g) of filtered saturated solution was transferred to a dry conical flask from solution thermostated at all experimental temperatures. The saturated solubility analyses of Gly, Ala, Aba and Val were made by the 'formol titrimetric method' [4,11,12,[19][20][21][22][23] using freshly standardized (0.05 molÁL -1 ) NaOH (GR, E Merck; [99.0 %) solution and 1 % alcoholic phenolphthalein solution as indicator. The solubilities were measured at the natural pHs of the solutions.…”

Section: Methodsmentioning

confidence: 99%

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Chemical Transfer Energetics of a Series of Homologous α-Amino Acids in Quasi-Aprotic 2-Methoxyethanol–Water Mixtures

2016

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The zwitterionic solvation behavior of a series of the homologous a-amino acids glycine (Gly), DL-alanine (Ala), DL-a-amino butyric acids (Aba) and DL-nor-valine (Val), in water and in aqueous mixtures of 2-methoxyethanol, have been studied at equidistant temperature intervals in the range of 288.15-308.15 K, using the solubility method. The solubility data were analyzed according to the 'formol titrimetric' process. Standard Gibbs energies DG 0 t ðiÞ and entropies DS 0 t ðiÞ of transfer were calculated and are discussed. The observed DG 0 t ðiÞ and TDS 0 t ðiÞ versus composition profiles are complicated because of the various interaction effects. The chemical effects of the transfer Gibbs energies DG 0 t;ch ðiÞ and entropies of transfer TDS 0 t;ch ðiÞ have been obtained after elimination of the cavity effect, estimated by the scaled particle theory and dipole-dipole interaction effects, calculated by use of the Keesom orientation expression. The chemical contributions to transfer energetics of homologous a-amino acids are guided by the combined effects of increased dispersion interaction, basicity and decreased acidity, hydrogen bonding effects and hydrophilic hydration of aqueous 2-methoxy ethanol as compared to that of reference solvent, water. In this context the solvating characters of protic ethylene glycol are also referred to for comparison.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Chemical Transfer Energetics of a Series of Homologous α-Amino Acids in Quasi-Aprotic 2-Methoxyethanol–Water Mixtures

2016

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“…2,32 The solubilities of l -α-alanine and dl -α-alanine in water are almost the same, with log C w = 0.260. 34−37,39,44−48 Solubilities are also known in organic solvents, 34−36,38,39,41−48 water–methanol mixtures 33,36 and water–ethanol mixtures. 33,36,37 We used log C w = 0.260 to convert solubilities into values of log P through eq 4, see Tables 6 and 7.…”

Section: Resultsmentioning

confidence: 99%

“…There is less data for α-aminobutanoic acid, but log P values into wet octan-1-ol 2 and wet butan-1-ol are available, 32 and solubilities in water, 45,46,49,50 organic solvents, 41,42,44,45 and water–ethanol 37 mixtures have been determined for dl -α-aminobutanoic acid. Values of log C and derived values of log P are in Table 8, the latter using a value of 0.333 for log C w for water.…”

Section: Resultsmentioning

confidence: 99%

Solvation Descriptors for Zwitterionic α-Aminoacids; Estimation of Water–Solvent Partition Coefficients, Solubilities, and Hydrogen-Bond Acidity and Hydrogen-Bond Basicity

Abraham

Acree

2019

ACS Omega

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The literature data on solubilities and water–solvent partition coefficients have been used to obtain properties or “Absolv descriptors” for zwitterionic α-aminoacids: glycine, α-alanine (α-aminopropanoic acid), α-aminobutanoic acid, norvaline (α-aminopentanoic acid), norleucine (α-aminohexanoic acid), valine (α-amino-3-methylbutanoic acid), leucine (α-amino-4-methylpentanoic acid), and α-phenylalanine. Together with equations that we have previously constructed, these descriptors can be used to estimate further solubilities and partition coefficients in a variety of organic solvents and in water–methanol and water–ethanol mixtures. It is shown that equations for neutral solutes are inadequate for the description of solubilities and partition coefficients for these α-aminoacids, and our equations developed for use with both neutral and ionic solutes must be used. The Absolv descriptors include those for hydrogen-bond acidity, A , and hydrogen-bond basicity, B . We find that both of these descriptors are far smaller in value than those for compounds that contain the corresponding ionic groups. Thus, A for α-alanine is 0.28, but A for the ethylammonium cation is 1.31; B for α-alanine is 0.83, and yet B for the acetate anion is no less than 2.93. The additional descriptors that we developed for equations that involve ions, J + and J – , are very significant for the α-aminoacids, although numerically smaller than for ionic species such as EtNH 3 + and CH 3 CO 2 – .

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Solvation Chemistry of DL‐Nor‐Valine in Aqueous Mixture of Dipolar Aprotic N,N‐Dimethyl Formamide

Mahali

Roy

Dolui

2014

J Chinese Chemical Soc

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In this article, we reported the solubilities of the amino acid DL-nor-valine (VAL) at five equidistant temperatures i.e. from 15 to 35°C in aqueous mixtures of N,N-dimethyl formamide (DMF). The Standard free energies (DG t 0 ( ) i ) and entropies (DS t 0 ( ) i ) of transfer of VAL from water to aqueous mixture of cationophilic dipolar aprotic DMF have been evaluated at 25°C. The transfer of Gibbs energies (DG t ch , 0 ( ) i ) and entropies (TDS t ch , 0 ( ) i ) due to the chemical effects have been obtained after elimination of cavity effect, estimated by the scaled particle theory and dipole-dipole interaction effects, computed by the used of Keesom-orientation expression. The chemical contribution of transfer energetics of DL-nor-valine (VAL) are mainly guided by the composite effects of increased dispersion interaction, basicity effect and decreased acidity, hydrogen bonding effects, hydrophilic hydration and hydrophobic hydration of aqueous DMF mixtures as compared to that of reference solvent, water.

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Thermodynamic solvation of a series of homologous α-amino acids in non-aqueous mixture of ethylene-glycol and N,N-dimethyl formamide

Cited by 45 publications

References 15 publications

Chemical Transfer Energetics of a Series of Homologous α-Amino Acids in Quasi-Aprotic 2-Methoxyethanol–Water Mixtures

Chemical Transfer Energetics of a Series of Homologous α-Amino Acids in Quasi-Aprotic 2-Methoxyethanol–Water Mixtures

Solvation Descriptors for Zwitterionic α-Aminoacids; Estimation of Water–Solvent Partition Coefficients, Solubilities, and Hydrogen-Bond Acidity and Hydrogen-Bond Basicity

Solvation Chemistry of DL‐Nor‐Valine in Aqueous Mixture of Dipolar Aprotic N,N‐Dimethyl Formamide

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