Table
I. Derivatives of 2-(p-Aminoaryl)-2-arylethylamines(Continued)
M.P.. C."
Compound 'V'-Carhethoxy-2- (4'-aminophenyl)-2-(4'-methoxypheny1)ethylamine monooxalate salt .V'-Carbethoxy-N- (2'-diethylaminoethy1)-2-(4'-aminophenyl) -2-phenylethylamine dioxalate salt AV'-Carhethoxy-N-(2 '-diethylaminoethyl)-2-(4'-aminodioxalate salt 3'-methylphenyl)-2-phenylethylamine !V'-Carbethoxy-N-(2'-diethylaminoethyl) -2-(4'-amino3'-chlorophenyl)-2-phenylethylamine dioxalate salt monohydrate i\"-Carbethoxy-N-(Z'-diethylaminoethyl)-2(4'-amino3'-methoxyphenyl)-2-phenylethylamine dioxalate salt .V'-Carhethoxy-5- (2'-diethylaminoethyl)-2- (4'-amino phenyl)-2-(4'-chlorophenyl)ethylamine dioxalate salt N'-Carbethoxy-N-(2'-diethylaminoethyl)-2-(4'-aminophenyl)-2-(4'-methoxyphenyl)ethylaminedioxalate salt monohydrate
Yield, c
Analysis, ( ' Solvent'
95-7
84"
3-7
190-3
41d
5
177-8
57d
5-8
170
42"
5
165
83d
9
169
57"
9
62'
5
180-1
C
H
59.39 59.11 57.53 57.18 58.22 57.92 52.62 52.45 56.65 56.39 54.22 54.18 54.98 54.87
5.98 6.22 6.62 6.87 6.80 6.90 6.21 6.23 6.62 6.63 6.07 6.94 6.76 7.05
N
CI
6.93 6.71 7.45 7.34 7.28 6.91 6.82 6.53 7.08 7.00 7.0.3 7.22 6.87 7.08
' Melting points were determined using a copper block and are uncorrected. "Recrystallization solvents used: 1. methanol, 2. water,
3 . benzene, 4. chloroform, 5. ethanol, 6. petroleum ether (h.p. 60 to 7 l 2 C . ) , 7. tetrahydrofuran, 8. ethyl acetate, 9. isopropyl alcohol. Where two numbers are indicated, co-solvents were used. ' Analyses by Midwest Microlab, Inc., Indianapolis, Ind. First series calculated, second found. " Yield includes the step of salt formation.
LITERATURE CITED (1) Damschroeder, R.E., Shriner, R.L., J. A m . Chem. SOC.5 8 , 1610 (1936). (2) Davis. R.B.,Benigni,,J.D..J.CHEM.ENG.DATA8, 578 (1963). ( 3 ) Davis, R.B., Buckler. R.T., Carlos, D.D., Ibid., 13, 132 (1968). (4) Fieser, L.F., "Experiments in Organic Chemistry," 3rd ed., pp. 105-6, Heath, Boston, Mass.
(5) Peak, D.A., \Vatkins, T.I., J . Chem. SOC.19.50, p. 445. (6) Vogel, A.I.. "A Text-Book of Practical Organic Chemistry." 3rd ed.. p. 554, Method 2. Longmans, Green, London. 1957.
RECEIVEDfor review March 10, 1967. Accepted September 29. 1967. Research supported in part by Sational Science Foundation Grant NSF-G19165.
Thermodynamic Studies of Hydrochloric Acid
1
in Tetra hyd rof ura n-Wa ter Mixtures RABINDRA N. ROY' and BUDDHADEV SEN Louisiana State University, Baton Rouge, La.
1
1
The cell, Pt, H,( 1 atm.) HCl(m), tetrahydrofuran ( X ) , water ( V ) Agcl, Ag, has been used to investigate the thermodynamic properties of hydrochloric acid. Activity coefficients, medium effects, relative partial molal heat contents, and heat capacities for X = 8.98, 18.21, 4 7 . 2 0 , 73.03, and 89.00 weight O h tetrahydrofuran a t various temperatures have been calculated.
THE
ultimate purpose of' our research program is to investigate the effect of the solvent on the thermodynamics of chemical equilibria ( I , 6, 13). Hydrochloric acid appeared t o be the most natural first choice as the system to study, aimed a t finding an analytical function for the so-called medium effects. T o calculate the thermodynamic properties of hydrochloric acid in aqueous-organic mixed solvents (2-5, 8-9), the standard potential ( 2 2 ) of the reversible cell Pt, H 2 (1 atm.) 1 HCl ( m ) , T H F (XI, H2O ( Y ) i AgC1, Ag, was evaluated by a polynomial curve-fitting program. The cell was used to determine the activity coefficients, medium effects, relative partial molal heat contents, and relative partial molal heat capacities of hydrochloric acid for five different systems and a t four different temperatures. This paper also describes the means of converting the values obtained from the mixed-solvent systems to those of the standard reference aqueous state by computational technique. The primary and secondary medium effects ( 1 0 ) are calculated in tetrahydrofuran (THF)-water ( 1 1 ) and 1,Z-dimethoxyethane-water ( 7 ) mixtures.
' Present address:
THEORY
The mean activity coefficients of hydrochloric acid in the mixed solvents were calculated from the following rearranged Kernst equation: " E " - ['E + ( 2 R T / F )In m ] (2RTiF)
In?.=
in which 'E" is the standard potential in the mixed solvent and ' E corresponds to (4)-i.e., the potential corrected to a hydrogen pressure of 1 atm. The primary medium effect is considered to be due to the difference in the solution energies in two different solvents and also is a measure of the energy involved in the transfer of an ion a t an infinite dilution in one solvent to an infinite dilution of another solvent. This effect (log trP HC1) of tetrahydrofuran-water mixtures upon hydrochloric acid was calculated from the equation:
Drury College, Springfield, Mo.
VOL. 13, N o . 1 , JANUARY 1968
79
Table I. Values of the M e a n Activity Coefficients of Hydrochloric Acid in Tetrahydrofuran-Water Mixtures a t Various Temperatures
m
X = weight ' of tetrahydrofuran O'C. 25- C . 13 c.
33.
c.
x=O 0.1 0.05 0.02 0.01 0.005 0.002 0.001 0.0005 0.0002 0.0001
0.8027 0.8346 0.8774 0.9065 0.9303 0.9541 0.9668 0.9756 0.9848 0.9890
0.1 0.05 0.02 0.01 0.005 0.002 0.001 0.0003 0.0002 0.0001
0.784 0.820 0.869 0.901 0.926 0.951 0.965 0.975 0.984 0.988
0.1 0.05 0.02 0.01 0.005 0.002 0.001 0.0005 0.0002 0.0001
0.766 0.809 0.863 0.897 0.923 0.950 0.964 0.974 0.983 0.988
0.02 0.01 0.005 0.002 0.001 0.0005 0.0002 0.0001
0.806 0.853 0.891 0.928 0.948 0.963 0.976 0.984
0.1 0.05 0.02 0.01 0.005 0.002 0.001 0.0005 0.0002 0.0001
0.327 0.349 0.448 0.543 0.636 0.742 0.806 0.857 0.906 0.932
0.1 0.05 0.02 0.01 0.005 0.002 0.001 0.0005 0.0002 0.0001
0.144 0.162 0.204 0.265 0.349 0.479 0.578 0.670 0.770 0.829
0.8000 0.8329 0.8770 0.9055 0.9297 0.9530 0.9661 0.9757 0.9844 0.9890
0.7964 0.8304 0.8755 0.9048 0.9285 0.9521 0.9656 0.9752 0.9842 0.9891
0.7918 0.8265 0.8731 0.9025 0.9268 0.9513 0.9647 0.9745 0.9838 0.9886
0.756 0.803 0.860 0.895 0.922 0.949 0.963 0.973 0.983 0.988
0.746 0.797 0.857 0.893 0.921 0.948 0.962 0.973 0.983 0.988
0.745 0.797 0.857 0.893 0.921 0.948 0.963 0.973 0.983 0.987
0.739 0.793 0.854 0.891 0.920 0.948 0.962 0.973 0.982 0.987
0.801 0.848 0.886 0.924 0.945 0.960 0.974 0.981
0.792 0.838 0.877 0.917 0.939 0.956 0.971 0.979
0.276 0.312 0.416 0.511 0.607 0.719 0.788 0.843 0.896 0.925
0.240 0.287 0.397 0.496 0.594 0.709 0.781 0.838 0.893 0.923
0.105 0.118 0.147 0.196 0.271 0.398 0.503 0.604 0.719 0.789
0.077 0.088 0.112 0.156 0.226 0.350 0.457 0.563 0.687 0.763
x = 8.98 0.763 0.806 0.862 0.896 0.923 0.949 0.963 0.974 0.983 0.988
X = 18.21 0.758 0.804 0.861 0.896 0.923 0.949 0.964 0.974 0.983 0.988
X = 47.20 0.802 0.849 0.887 0.925 0.946 0.961 0.975 0.982 X = 73.03 0.296 0.341 0.444 0.535 0.626 0.733 0.798 0.851 0.901 0.929
x = 89.00 0.118 0.132 0.173 0.233 0.316 0.448 0.551 0.647 0.733 0.816
"Data corresponding to X = 0 taken from Harned and Owen ( 1 ) .
80
in which "E" is the standard potential of the cell in aqueous medium relative to the unit value at infinite dilution in pure water, and i' ot:y- is the mean activity coefficient of hydrochloric acid a t zero molality in a mixed solvent referred to unity at infinite dilution in the aqueous state. A secondary medium effect is defined as due to the difference in ion-ion interactions in two different solvents and is thermodynamically represented by:
in which superscripts u: and s indicate that the measurements are being carried out in water and in mixed solvent, respectively. Subscripts LC and s on the mean activity coefficients ( y = ) indicate that y = is measured relative to unit value at infinite dilution in water and in mixed solvents, respectively. The term on the left-hand side represents the total medium effect and the terms on the right-hand side represent the primary and secondary medium effects, respectively. A relative partial molal property may be defined as the difference between the partial inolal property in a given solution and its value in the reference state-Le., relative to infinite dilution of the solvent. Determination of the relative partial molal heat content, E?, from electromotive force measurements depends on the accuracy with which the temperature coefficient of the electromotive force can be determined. E > can be computed from the equation
E?= -F
(a
- a,,j
+F
(C -
c,)T'
(4)
in which T represents the absolute temperature in degrees Kelvin and the constants a , a,, etc., can be determined from the following quadratic equations,
+ bT + cT'
(5)
a,, + b,,T + c,,T2
(6)
s). =
a
and s? =
The relative partial molal heat capacity, J., of electrolytes (hydrochloric acid) in mixed solvents can be computed from the equation
Ti = 2 F (C - C,,jT
(71
in which coefficients e, eo, etc., are easily determined by the method of least squares from the e.m.f. data a t various temperatures. EXPERIMENTAL
Purification of the solvent, preparation of the solution, and other experimental details have been described ( 1 2 ) . RESULTS AND DISCUSSION
The mean activity coefficients of hydrochloric acid given in Table I were calculated by computer (IBM 1620), using
Table II. Primary Medium Effect (log HCI) of Tetrahydrofuran-Water Mixtures upon Hydrochloric Acid a t Various Temperatures
X = weight
Lc
of tetrahydrofuran
X
0" c.
15. c.
23.
c.
350 c.
8.98 18.21 47.20 73.03 89.00
0.0173 0.1838 0.3035 1.0199 1.8689
0.0609 0.1569 0.3668 1.0227 2.0233
0.0732 0.1571 0.4373 1.0924 2.0975
0.0517 0.1420 0.4083 1.1641 2.2289
JOURNAL OF CHEMICAL AND ENGINEERING DATA
Equation 1. The appropriate values of standard potential ("E")and observed potentials ('E) were obtained from the tables published earlier ( 1 2 ) . A careful examination of the data listed in Table I shows that in a given system and a t a given temperature, the increase in the value of the mean activity coefficient corresponds to the decrease in molality of hydrochloric acid. The activity coefficients a t any concentration decrease with increasing temperature. The general trends of our results (THF-H,O) are in close agreement with those obtained by Harned and his coworkers in other mixed solvents (2-5, 8-9). For X = 8.98 and
Table IV. Coefficients of the Empirical Equation: Eabrd= a bJ cTZ
+
a x 10'
m
b x lo3
+
c x lo6
Standard Error
-3.68755 -0.25967 0.18243 4.85265 5.73599 16.72599
0.00119 0.00071 0.00064 0.00053 0.00055 0.00581
-3.40445 -4.23599 -4.22001 -3.97602 -4.39029 -4.3089 1
0.00248 0.00201 0.00192 0.00157 0.00134 0.00124
X = 8.98 0.089050 0.044490 0.035190 0.007790 0.004620 0.002310
10.86695 39.46164 43.27598 83.11505 90.79479 185.29968
0.09440 0.045010 0.035600 0.013140 0.004670 0.002340
10.40319 3.15607 3.10113 4.53758 0.38614 0.75561
1.90426 0.03532 -0.18656 -2.66683 -3.10026 -9.44101
X = 18.21 Table Ill. Secondary Medium Effect of TetrahydrofuranWater Mixtures upon Hydrochloric Acid ot Various Temperatures
X = weight m
0-
c.
of tetrahydrofuran In" c. 2
