Volumetric behaviour of binary mixtures of (trichloromethane + amines) at temperatures between T = (288.15 and 303.15) K at p = 0.1 MPa

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Abstract

In this work, densities of binary mixtures of {trichloromethane (TCM) + n-butylamine (n-BA), or + s-butylamine (s-BA), or + diethylamine (DEA), or + triethylamine (TEA)} have been determined under atmospheric pressure as a function of composition and temperature using a vibrating-tube densimeter. The temperatures studied were T = (288.15, 293.15, 298.15, and 303.15) K. The excess molar volumes (VmE), calculated from density data are negative for all studied systems and the negative deviations follow the sequence: TEA > DEA > s-BA > n-BA. Negative values of VmE for binary mixtures were attributed to the formation of hydrogen bonding and of a charge transfer complex between TCM and amines and to structural effects. The partial molar volumes at infinite dilution of each component (V¯ioo) have been determined using three different methods.

Introduction

This study is a continuation of our investigation on the volumetric properties of binary mixtures containing chloroalkanes as one of components [1], [2], [3]. We report in this work volumetric properties of {trichloromethane + n-butylamine (n-BA), or +s-butylamine (s-BA), or diethylamine (DEA), or +triethylamine (TEA)}, as a function of composition, at temperatures between T = (288.15 and 303.15) K and p = 0.1 MPa. These results are useful to elucidate possible interactions that occur between the compounds present in solutions.

The most important use of trichloromethane is in the production of monochlorodifluorimethane used as a refrigerant. It is still used as an extractant for pharmaceutical products [4]. Diethylamine is used principally for the production of vulcanization accelerators [5]. Triethylamine is used as an organic acid acceptor in the most diverse syntheses, or as a salt former in precipitation or purification operations. Other important fields of use include polyurethane catalysts, anticorrosion agents, textile, and photographic auxiliaries, and anodic electrocoating [5]. Butylamines are used principally for the synthesis of vulcanization accelerators of the sulfenamide type, as intermediate for the production of plasticizers, agrochemicals, and drugs [5].

Thermodynamics properties of binary liquid mixtures of chloroalkanes with amines have been studied by Oswal et al. [6] (alkylamine + haloalkanes), Resa et al. [7] (diisopropylamine + chloroform), Acevedo et al. [8] (di-n-butylamine + chloroalkanes), Acevedo et al. [9] (n-butyl-1-butanamine + chloroalkanes), Acevedo and Katz [10] (amines + chloroalkanes), Acevedo and Katz [11] (n-butylamine + chloroalkanes), Schutte et al. [12] (chloroform + triethylamine), Hepler et al. [13] (chloroform + triethylamine), Kopečni et al. [14] (tri-n-alkylamine + chloroalkanes), Handa et al. [15] (triethylamine + chlorolakanes), Chand et al. [16] (triethylamine + trichloromethane), and Hepler and Fenby [17] (triethylamine + chloroform).

Section snippets

Experimental

Trichloromethane (Merck, PA, mole fraction purity >0.990). The origins of the amines with their purity are: n-butylamine (Acros, mole fraction purity >0.995), s-butylamine (Aldrich, mole fraction purity >0.990), diethylamine (Fluka, mole fraction purity >0.990) and triethylamine (Acros, mole fraction purity >0.990). The components were purified by using the methods described in the literature [18]. The purity of each substance was evaluated from measurements of density by comparing the

Results

The excess molar volume is defined byVmE=Vm-x1V1o-x2V2o,in which Vm represents the volume of a mixture containing 1 mol of (trichloromethane + amine), x1 and x2 are the mole fractions of components 1 (trichloromethane) and 2 (amine), respectively, and V1o and V2o are the molar volumes of pure components.

The VmE can be expressed by the following equationVmE=x1M1(1/ρ-1/ρ1)+x2M2(1/ρ-1/ρ2),in which M1, M2, ρ1 and ρ2 represent the molar masses and densities of the pure components, respectively, and ρ

Discussion

FIGURE 1, FIGURE 2, FIGURE 3, FIGURE 4 show the values of excess molar volumes for the studied systems together with the smoothing curves using equation (3) for several temperatures.

The results presented in table 2 and FIGURE 1, FIGURE 2, FIGURE 3, FIGURE 4 indicate that VmE is negative over the entire composition range for all systems studied and the negative deviations for different amines are: tertiary > secondary > primary. The negative deviations follow the order: TCM + TEA > TCM + DEA > TCM + s-BA > TCM + n

Acknowledgements

The authors wish to express their gratitude to Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP, No. 99/12778-7) for financial support. J.G. Magalhães thanks also to Conselho Nacional de Desenvolvimento Cientı´fico e Tecnológico (CNPq) for the scholarship.

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