2-Methyl Pyrazine(2MP)을 포함하는 이성분 및 삼성분

혼합계의 298.15K에서의 과잉몰부피

한규진, 오종혁, 원동복, 박소진, 최명재*, 이상봉*, 김병현*

충남대학교 공과대학 화학공학과

*한국화학연구소

Excess Molar Volumes of Binary and Ternary Mixtures

Containing 2-Methyl Pyrazine(2MP) at 298.15K

Kyu-Jin Han, Jong-Hyeog Oh, Dong-Bok Won, So-Jin Park

Myoung-Jae Choi*, Sang-Bong Lee*, Byoung-Hyun Kim*

Dept. of Chemical Engineering, Chungnam National University

*Advanced Chemical Technology Division, KRICT

INTRODUCTION

Studies on excess molar volumes(vE) and viscosity deviations(□□) of liquid mixtures are of considerable importance in understanding the nature of molecular interactions.[1] Many investigations have already been carried out to get insight into the nature and degree of interactions that are present in binary mixtures, but that of ternary mixtures are quite rare in the literatures. It is therefore interesting to determine or estimate excess functions of ternary mixtures from related binary data.[2,3]

In this work the excess molar volumes were determined from experimental densities for the three corresponding binary systems and ternary system consisted of ethyl acetate(1), cyclohexane(2), 2-methyl pyrazine(3) and ethyl acetate(1), n-hexane(2), 2-methyl pyrazine(3). 2-Methyl pyrazine(2MP) is used for several commercial applications, especially as a pharmaceutical intermediate compound for anti Tuberculosis. The experimental data were correlated with Redlich-Kister polynomial[4] and Cibulka's equation[1] for the binary and ternary systems respectively. And for the ternary systems, vE data were predicted using Radojkovi□'s equation and compared with the experimental and correlated values.

THEORETICAL

The vE (cm3 mol-1) for binary mixture are calculated according to eq. (1) from the experimental pure and mixture density.

[eqn: v_12^E = left[ {x_1 `M_1 + x_2 `M_2 } over {rho_m} right] - {x_1 `M_1} over {rho_1} - {x_2 `M_2} over {rho_2} `]	(1)

where xi, Mi , i and m are the molar fraction, molar mass, density of pure component i and  density of binary mixture respectively.

Redlich-Kister polynomial[4] was used to describe the composition dependence of the experimental vE data.

[eqn: v_12^E = x_1`x_2 SUM_i=1^n A_i (x_1 -x_2 )^i-1 `]	(2)

where, [eqn: A_i`] is an adjustable parameter and n is the number of fitted parameters [eqn: A_i`].

The standard deviations of the fits [eqn: sigma_st`] are defined as

[eqn: sigma_st = left[ {SUM_i `left( v_{rm cal}^E - v_exp^E right)_i^2} over {(N-n)} right]`]	(3)

where N is the number of experimental data points.

For the ternary system, excess molar volume is calculated using the following equation

[eqn: v_123^E = left[ {x_1 `M_1 + x_2 `M_2 + x_3 `M_3} over {rho_m} right] - {x_1 `M_1} over {rho_1} - {x_2 `M_2} over {rho_2} - {x_3 `M_3} over {rho_3} `]	(4)

Radojkovi□ et al considered an expression proposed by Redlich and Kister for the ternary system

[eqn: v_123^E `=` v_12*^E + v_23*^E + v_13*^E `]	(5)

where [eqn: v_12*^E`], [eqn: v_23*^E`] and [eqn: v_13*^E`] represent the excess molar volumes with x1, x2 and x3 mole fractions of the ternary system calculated from eq.(2).

And Cibulka proposed the following equation as modification of Radojkovi□'s equation.

[eqn: v_123^E `=` v_12*^E + v_23*^E + v_13*^E + x_1`x_2`x_3`(A+Bx_1 +Cx_2 )`]	(6)

EXPERIMENTAL

Materials  All the chemicals used in this investigation were of pure analytical commercial grade of purity and doubly distilled water was used. 2MP were from the Aldrich Chemical Co., and the other chemicals are supplied from Junsei Chemical Co. They were used after water was dried over molecular sieves having a pore diameter of 0.4nm. The purities of chemicals checked by gas chromatography were above 99.9wt%.

Apparatus and Procedure   vE are calculated from directly measured densities of pure and mixture samples. Densities are measured using a digital vibrating glass tube densimeter (Anton Paar, model DMA 48, Graz, Austria). The uncertainty of this densimeter is less than ±1×10-4 g-cm-3. Before each set of measurements, the apparatus was calibrated with doubly distilled water and dried air. Samples were prepared in ca 5 □ vial by mass using AND model HA-202M digital microbalance with an accuracy of ±1×10-5g, according to approximately calculated mole ratio. The operating procedure has been described elsewhere[5].

RESULTS AND DISCUSSIONS

Binary Systems   The density of binary mixtures are measured and excess volumes of mixing are calculated as a function of composition for same binary systems at 298.15K, are given in Figure 1 and Figure 2. The vE values were calculated by means of the eq.(1). The ethyl acetate(EA)+2MP system shows a small negative deviation from the ideal. The vE values of EA+ cyclohexane, EA+n-hexane and cyclohexane+2MP show relatively large positive deviations. And the vE values of n-hexane+2MP system are negative at lower concentration and change to positive at higher concentration of n-hexane. All the experimental values were correlated with Redlich-Kister polynomial. Figure 1 shows the good agreement between experimental data points and solid lines, which were calculated with correlated parameters. The adjustable parameters and standard deviations from the experimental values are listed in Table 1.

Ternary systems   Figure 3 and Figure 4 show the experimental values of excess molar volumes for the ternary systems of EA(1)+cyclohexane(2)+2MP(3) and EA(1)+n-hexane(2)+2MP(3) at 298.15K. From the correlation using eq.(6), the parameters obtained for [eqn: v_123^E`] are A=-2.6710, B=0.9105 and C=-0.7671. And the standard deviation from the experimental values is 0.033.

ACKNOWLEDGEMENT

The authors thank KRICT(Korea Research Institute of Chemistry and Technology)□for financial support.

REFERENCES

1. G. C. Pedrosa, J. A. Salas and M. Katz : Thermochimica Acta, 160, 243 (1990)

2. M. Dominguez, A. Gamacho, M. C. Lopez, F. M. Royo and J. S. Urieta : Can. J. Chem., 73, 896 (1995)

3. S. Martinez, R. Garriga, P. Perez and M. Gracia : Fluid Phase Equilibria, 168, 267 (2000)

4. O. Redlich and A.T.Kister : Ind. Eng. Chem., 40, 345 (1948)

5. J. H. Oh and S. J. Park : J. Chem. Eng. Data, 43, 1009 (1998)

Table 1. The adjustable parameters(Ai) and standard deviations([eqn: sigma_st`]) for the binary systems at 298.15K

parameter	EA(1)+cyclohexane(2)+2MP(3)			EA(1)+n-hexane(2)+2MP(3)
	(1)+(2)	(2)+(3)	(1)+(3)	(1)+(2)	(2)+(3)	(1)+(3)
A1	4.5300	3.1319	-0.8823	3.4427	0.0369	-0.8823
A2	-0.5890	1.5084	-0.0877	1.1110	2.3759	-0.0877
A3	0.7500	0.5210	-0.0461	0.8533	-0.5579	-0.0461
A4	0.1610	-0.0232	0.0216	-0.3992	1.1275	0.0216
A5	-0.9210	0.1417	-0.0859	-0.8077	1.3095	-0.0859
[eqn: sigma_st`]	0.0119	0.0103	0.0118	0.0274	0.3760	0.0118

Figure 1. Excess molar volumes for the three corresponding binary systems of EA(1), cyclohexane(2) and 2-methyl pyrazine(3) at 298.15K.	Figure 2. Excess molar volumes for the three corresponding binary systems of EA(1), n-hexane(2) and 2-methyl pyrazine(3) at 298.15K.

Figure 3. Line of constant excess molar volumes (cm3mol-1) for the ternary system of EA(1)+cyclo- hexane(2)+2MP(3) at 298.15K.	Figure 4. Line of constant excess molar volumes (cm3mol-1) for the ternary system of EA(1)+ n-hexane(2) +2MP(3) at 298.15K.