Thermodynamics of hydrogen bonding of weak bases in alcohol solutions: Calorimetry of solution, IR-spectroscopy and vapor pressure analysis

In the paper, results of calorimetric measurements, IR spectra, and calculated ab initio stabilization energies of dimers are reported for binary systems butan-2-one + (methanol, ethanol, propan-1-ol, butan-1-ol, and chloroform). Changes in the total enthalpy of specific interactions due to dissolution of butan-2-one in the alcohols, calculated using equations derived in previous works, are positive. That results from the endothermic breaking of the O-H···O-H bonds not completely compensated by the exothermic effects of formation of the O-H···O═C ones. Moreover, the concentration of nonbonded molecules of butan-2-one is significant even in dilute solutions, as is evidenced by the shape of the C═O stretching vibrations band in the IR spectra. Apart from that, the spectra do not confirm 1:2 complexes in spite of two lone electron pairs in the carbonyl group of butan-2-one capable of forming the hydrogen bonds. The changes in enthalpy of specific interactions are negative for dilute solutions of alcohols and chloroform in butan-2-one and of butan-2-one in chloroform, because no hydrogen bonds occur in pure butan-2-one. The experimental results are positively correlated with the enthalpies estimated from the ab initio energies using a simple "chemical reaction" approach.

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“…The following formula derived previously 23,40 was used to calculate the specific interactions enthalpy …”

Section: Limiting Partial Enthalpies Of Solution and Thementioning

confidence: 99%

Positive and Negative Contributions in the Solvation Enthalpy due to Specific Interactions in Binary Mixtures of C1–C4 n-Alkanols and Chloroform with Butan-2-one

et al. 2015

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“…Enthalpies of solution were measured at 298.15 K using handmade semi-adiabatic calorimeter as described earlier. [ 21 22 ] The weight of the solute samples was 0.04–0.06 g. Obtained values of solution enthalpies correspond to the limiting dilution conditions which were confirmed by the absence of concentration dependence of solution enthalpies within the boundaries of their uncertainties. Each experiment was reproduced at least 4 times.…”

Section: Methodsmentioning

confidence: 53%

Thermodynamics of dissolution and infrared-spectroscopy of solid dispersions of phenacetin

Gerasimov

Varfolomeev

Зиганшин

et al. 2016

J Adv Pharm Technol Res

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In this work enthalpies of dissolution in water of polyethylene glycols (PEGs) having an average molecular weight of 1000 and 1400, Pluronic-F127, phenacetin as well as the composites prepared from them were measured using solution calorimetry at 298.15 K. Intermolecular interaction energies of polymer-phenacetin were calculated on the basis of an additive scheme. It was shown that for mixtures with high content of polymer (>90 wt%) Pluronic-F127 has the highest solubilizing effect, while for mixtures with (4–6):1 polymer: phenacetin ratio the best solubilizing agent is PEG-1400. Infrared-spectra showed a decrease of the number of self-associated molecules of phenacetin with increasing of polymer content in the composites. The obtained results enabled us to identify the features of intermolecular interactions of polymers with a model hydrophobic drug and may be used for optimizing the conditions for preparing solid dispersions based on hydrophilic polymers.

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“…(1) to solute-solvent interaction data of 18-crown-6 (s) and 1,4-dioxane (l). interact with the solute as a proton donor without (a considerable) disruption of (the strong) alcohol-alcohol hydrogen bonds" [33], thus compromising the effectiveness of the overall solute-alcohol interaction.…”

Section: Discussionmentioning

confidence: 99%

Use of quantitative structure–property relationships to study the solvation process of 18-crown-6

et al. 2015

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Thermodynamics of hydrogen bonding of weak bases in alcohol solutions: Calorimetry of solution, IR-spectroscopy and vapor pressure analysis

Cited by 23 publications

References 64 publications

Positive and Negative Contributions in the Solvation Enthalpy due to Specific Interactions in Binary Mixtures of C1–C4 n-Alkanols and Chloroform with Butan-2-one

Positive and Negative Contributions in the Solvation Enthalpy due to Specific Interactions in Binary Mixtures of C1–C4 n-Alkanols and Chloroform with Butan-2-one

Thermodynamics of dissolution and infrared-spectroscopy of solid dispersions of phenacetin

Use of quantitative structure–property relationships to study the solvation process of 18-crown-6

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