Excess molar enthalpies for binary mixtures of trimethyl phosphate with alkanols {CH3(CH2)nOH, n = 0–3} at 298.15 K

doi:10.1016/j.tca.2008.02.015

Thermochimica Acta

Volume 471, Issues 1–2, 30 May 2008, Pages 100-102

https://doi.org/10.1016/j.tca.2008.02.015 Get rights and content

Abstract

The excess molar enthalpies ( $H_{m}^{E}$ ) for the binary mixtures of trimethyl phosphate (TMP) with alkanols {CH₃(CH₂)_nOH, n = 0–3} have been measured with an isothermal calorimeter at 298.15 K and atmospheric pressure. The $H_{m}^{E}$ values are positive for all the mixtures over the whole composition range. The values increase in the order methanol < ethanol < 1-propanol < 1-butanol. The experimental results have been correlated with the Redlich–Kister equation.

Introduction

The study of hydrogen bonded systems involving organic phosphates is of considerable significance for a variety of reasons. Organic phosphates–water systems serve as model systems for understanding biological processes [1], [2], [3]. Organic phosphates also have widely industrial applications, as extractant used together with diluent in a number of solvent extraction processes [4], [5], [6], as flame-retardant to reduce the electrolyte flammability in lithium ion cells [7], [8]. Because of its importance in influencing a variety of chemical and biochemical processes, a number of studies on the hydrogen bonded interactions of organic phosphates, such as trimethyl phosphate (TMP) and tributyle phosphate (TBP), with the proton donors, such as water and alcohols, have been reported [9], [10], [11], [12], [13], [14]. These studies are mainly performed using IR, NMR, and computation.

The thermodynamic properties, especially the excess molar enthalpy for hydrogen bonded systems, are important and useful for understanding the formation of hydrogen bonded complex. The thermodynamic properties for a few mixtures involving TMP or TBP have been studied [15], [16], [17], [18], [19], but the excess molar enthalpy $H_{m}^{E}$ of TMP with alkanols over the whole composition range has not been reported. Continuing our interesting in the $H_{m}^{E}$ of TBP with alkanols [18], the excess molar enthalpies for the mixtures of (trimethyl phosphate + methanol/ethanol/1-propanol/1-butanol) at 298.15 K and atmospheric pressure are reported in the present paper.

Section snippets

Materials

Trimethyl phosphate (AR, mole fraction >0.99, Alfa), methanol (GR, mole fraction >0.995, Sinopharm Group Chemical Reagent Co., Ltd.), ethanol (GR, mole fraction >0.995, Sinopharm Group Chemical Reagent Co., Ltd.), 1-propanol (AR, mole fraction >0.998, Tianjin Bodi Chemical Co., Ltd.), 1-butanol (AR, mole fraction >0.998, Tianjin Bodi Chemical Co., Ltd.) were used without further purification other than drying with 3A (Ø 3–5 mm, spherical) molecular sieves. Care was taken to protect the samples

Results and discussion

The experimental values of $H_{m}^{E}$ are listed in supplement and shown in Fig. 2. The experimental data were regressed with all points weighted equally by the Redlich–Kister equation: $H_{m}^{E} (J mo l^{- 1}) = x (1 - x) \sum_{n = 1} A_{n} {(2 x - 1)}^{n - 1}$ where x is the mole fraction of TMP, A_n are fitting parameter, and n is the number of fitting parameters. These parameters are listed in Table 1 together with the standard deviation.

All systems (TMP + alkanols) showed endothermic and same behaviour over the whole range of composition,

Acknowledgement

This work was supported by the Key Program of National Natural Science Foundation of China (50434010).

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Enthalpy of solvation correlations for organic solutes and gases dissolved in 2-propanol, 2-butanol, 2-methyl-1-propanol and ethanol
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Citation Excerpt :
The ΔSolvHEtOH° database for enthalpy is published elsewhere [12,114]. In Table S4 we have tabulated the experimental ΔSolvHEtOH° values that have been added to the ethanol enthalpy of solvation data set, along with the pertinent literature references [20–24,28,36,60,93,96,107,115–117] for the added experimental values. We have assembled in Table S1 values of ΔSolvH2-PrOH° for 91 organic vapors and gases dissolved in 2-propanol covering a reasonably wide range of compound type and descriptor value.
Data have been assembled from the published literature on the enthalpies of solvation for 91 organic vapors and gaseous solutes in 2-propanol, for 73 gaseous compounds in 2-butanol, for 85 gaseous compounds in 2-methyl-1-propanol and for 128 gaseous compounds in ethanol. It is shown that an Abraham solvation equation with five descriptors can be used to correlate the experimental solvation enthalpies to within standard deviations of 2.25 kJ/mole, 1.99 kJ/mole, 1.73 kJ/mole and 2.54 kJ/mole for 2-propanol, 2-butanol, 2-methyl-1-propanol and ethanol, respectively. The derived correlations provide very accurate mathematical descriptions of the measured enthalpy of solvation data at 298 K, which in the case of ethanol span a range of 136 kJ/mole. Division of the experimental values into a training set and a test set shows that there is no bias in predictions, and that the predictive capability of the correlations is better than 3.5 kJ/mole.
Enthalpy of solvation correlations for organic solutes and gases dissolved in 1-propanol and tetrahydrofuran
2011, Thermochimica Acta
Data have been assembled from the published literature on the enthalpies of solvation for 103 organic vapors and gaseous solutes in 1-propanol and for 86 gaseous compounds in tetrahydrofuran. It is shown that an Abraham solvation equation with five descriptors can be used to correlate the experimental solvation enthalpies to within standard deviations of 2.35 kJ/mole and 2.10 kJ/mole for 1-propanol and tetrahydrofuran, respectively. The derived correlations provide very accurate mathematical descriptions of the measured enthalpy of solvation data at 298 K, which in the case of 1-propanol span a range of 119 kJ/mole. Division of the experimental values into a training set and a test set shows that there is no bias in predictions, and that the predictive capability of the correlations is better than 3.5 kJ/mole.
Density, Refractive Index, and Sound Velocity for the Binary Mixtures of Tri-n-Butyl Phosphate and n-Butanol between 303.15 K and 323.15 K
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Short communicationExcess molar enthalpies for binary mixtures of trimethyl phosphate with alkanols {CH3(CH2)nOH, n = 0–3} at 298.15 K

Abstract

Introduction

Section snippets

Materials

Results and discussion

Acknowledgement

Biochim. Biophys. Acta

J. Inorg. Biochem.

Chem. Biol. Interact.

Hydrometallurgy

J. Supercrit. Fluids

J. Power Sources

J. Power Sources

J. Mol. Struct.

Spectrochim. Acta Part A

Spectrochim. Acta Part A

Short communication
Excess molar enthalpies for binary mixtures of trimethyl phosphate with alkanols {CH₃(CH₂)_nOH, n = 0–3} at 298.15 K