2166
J. Phys. Chem. 1980, 84, 2166-2170
(15) M. Anbar, M. Bambenek, and A. B. Ross, Nan. Stand. Ref. Data Ser., ( U . S . Natl. Bur. Stand.), No. 43 (1973). (16) K.-D. Asmus, H. Mockel, and A. Henglein, J . Phys. Chem., 77, 1218 (1973). (17) J. Rabani, D.Klug-Roth, and A. Henglein, J. Phys. Chem., 78, 2089 (19741. (18) k-T. iin, W. Bottcher, M. Chou, C. Creutz, and N. Sutin, J. Am. Chem. Soc., 98, 6536 (1976). (19) E. Konig and S. Herzog, J. Inorg. Nucl. Chem., 32, 585 (1970). (20) F. Minisci, Top. Curr. Chem., 62, 1 (1976). (21) J. Lilie, G. Beck, and A. Henglein, Ber. Bunsenges. Phys. Chem., 75, 458 (1971). (22) (a) G. M. Waind and B. Martin, J. Inorg. Nucl. Chem., 8, 551 (1958); (b) B. R. Baker and D. Mehta, Inorg. Chem., 4, 848 (1965); (c) K. Morinaga, Rev. Polarogr., 14, 251 (1967); (d) S. Tsushima and T. Kitagawa, Nippon Kagaku Zasshi, 92, 405 (1971); (e) G. Kew, K. DeArmond, and K. Hanck, J. Phys. Chem., 78, 727 (1974); (f) D. M. Soignet and L. G. Hargis, Inorg. Chem., 14, 941 (1975); (g) G.
(23) (24) (25) (26) (27)
Kew, K. Hanck, and K. DeArmond, J. Phys. Chem., 79, 1828 (1975); (h) ref. 5; (i) M. Ciano, private communications. K. DeArmond and W. Halper, J . Phys. Chem., 75, 3230 (1971). W. Buratti, G. P. Gardini, F. Minisci, F. Bertini, R. Galli, and M. Perchinunno, Tetrahedron,27, 3655 (1971). W. A. E. McBtyde, "IUPAC Chemical Data Series", No. 17, Pergamon Press, Elmsford, NY, 1978. A. Cierio, F. Minisci, 0. Porta, and G. Sesana, J. Am. Chem. Soc., 99, 7960 (1977). A similar behavior, Le., only electron transfer to the substrate, has been observed when (CH,),COH radicals react with monoprotonated bipyriilne,1i8 phenanthroline,'i8, and acrkiine.28 It has been observed, however, that the reaction of (CH,),COH radicals with unprotonated acridine ives ca. 50% of an adduct and 50% of the reduced species. P. Neta, J. Phys. Chem., 83, 3096 (1979). L. Grossi, F. Minisci, and G. F. Pedulli, J. Chem. Soc., Perkin Trans. 2, 948 (1977).
P
(28) (29)
Binary Systems of Trichloroethylene with Benzene, Toluene, p-Xylene, Carbon Tetrachloride, and Chloroform. Ultrasonic Velocities and Adiabatic Compressibilities at 303.15 and 313.15 K, and Dielectric Properties and Refractive Indexes at 303.15 K Jagan Nath" and S. N. Dubey' Chemlstry Department, Gorakhpur University, Gorakhpur 27300 1, India (Received:October 9, 1979)
The dielectric constants and refractive indexes for binary mixtures of trichloroethylene with benzene, toluene, p-xylene, CCl,, and CHC13have been measured at 303.15 K. Also, the ultrasonic velocities in these binary liquid mixtures have been measured at 303.15 and 313.15 K by using a single crystal interferometer at a frequency of 2 MHz/s. The ultrasonic velocities have been used to calculate the adiabatic compressibilities for these systems at 303.15 and 313.15 K. The deviations, A€, in the dielectric constants of the various mixtures from the ideal volume fraction mixture law values have been found to be negative. This behavior has been ascribed to a decrease in the degree of alignment of dipoles of the various molecules. The values of the Kirkwood correlation parameter, g, which have been calculated in the case of the systems of C2HC13with CHC1, and toluene, show that these increase with increasing concentration of C2HC13in the mixture and become highest in pure C2HC18, thus indicating that dispersion forces between molecules and the geometric shape of the molecules are quite responsible for the changes in the degree of alignment of the dipoles. The values of the dipole moments of C2HC13as estimated in the solvents CC14and benzene show the existence of electron donor-acceptor interaction of C2HC13with CC14and benzene in the liquid state. The adiabatic compressibilities have been used to calculate the excess compressibilities, ,:k for the various systems at 303.15 and 313.15 K. The data show that for all of the systems, the values of k? change from either positive to less positive or from positive to negative with the decrease in temperature. This fact has been attributed to the increase in the strength of interaction of C2HC1, with the other components when the temperature is decreased. At both of the temperatures, the values of :k for equimolal mixtures of C2HC1Swith the aromatics have been found to have the sequence benzene > toluene > p-xylene. This has been explained by the increasing strength of electron donor-acceptor interaction of C2HC13with the aromatics having an increasing number of CH3 substituents in the aromatic ring. Introduction The binary systems of trichloroethylene (C2HCl,) with aromatics, carbon tetrachloride, and chloroform are of interest from the viewpoint of the existence of specific interaction between the components, since, on account of the presence of three C1 atoms and a r-electron system in C2HC13,it can act as both a u- and a-type sacrificial electron acceptor toward aromatics and a a-type electron donor toward CCll and CHC13. Extensive studies concerning the interactions between components of such systems have not been made. Only recently the measurements of excess volume^^^^ for binary systems of C2HC13with benzene, toluene, p-xylene, CC14,and CHC1, have been carried out at 303.15 and 313.15 K. But these do not provide useful information regarding the specific interaction between the components of various systems. The refractive index, n, and dielectric constant, E, measurements were expected to shed some light on the configu0022-3654/80/2084-2166$01 .OO/O
ration of molecules in the various mixtures and give some idea about the specific interaction between the components, since the Kirkwood correlation ~ a r a m e t e rg,, ~which is a measure of the degree of alignment of molecules in the liquid state, is related to E and n. Further, the adiabatic compressibilitie~~ as obtained from ultrasonic velocities in binary liquid mixtures are also known to give an estimate of the strength of interaction between unlike molecules of the components. Hence, the measurements of ultrasonic velocities in, and dielectric constants, refractive indexes, and adiabatic compressibilities of, binary liquid mixtures of C2HC13 with benzene, toluene, p-xylene, CC14, and CHC1, have been undertaken in the present program, and the results obtained have been interpreted in this paper. Experimental Section Materials. Benzene, toluene, chloroform, and carbon tetrachloride which were of GR or AR quality and tri0 1980 American Chemical Society
The Journal of Physical Chemistry, Vol. 84, No. 17, 1980 2167
Binary Systems of Tricliloroethylene
TABLE I: Dielectric Constants for the Various Mixtures'" of 'l'richloroet!iylene at 303.15 K X E g C HCl -Toluene 0.0000 2.365 0.93 0.1186 2.460 1.30 0.2261 2.544 1.50 0.3625 2.661 1.68 0.4429 2.741 1.7'9 0.5372 2.829 1.85 0.6441 2.983 1.910 0.7277 3.019 1.92 0.8296 3.130 1.95 0.9552 3.285 1.97 1.0000 3.337 1.98
x E g X E C, HC1 -CHCl C, HCI, -p-Xylene 0.0000 4.631 1.44 0.0000 2.252 0.0866 4.509 1.48 0.1282 2.293 0.1868 4.353 1.51 0.2636 2.405 0.2712 4.229 1.54 0.3666 2.502 0.3834 4.072 1.59 0.4699 2.603 0.4662 3.954 1.62 0.5687 2.712 0.4781 3.944 1.63 0.6708 2.819 0.5590 3.843 1.68 0.7620 2.933 0.5768 3.821 1.69 0.9838 3.311 0.7746 3.590 1.81 0.9881 3.314 0.9466 3.384 1.92 1.0000 3.337 1.0000 3.337 1.98
C,HCl, -Benzene 0.0000 2.268 0.0084 2.270 0.0119 2.277 0.0129 2.301 0.0621 2.333 0.0972 2.366 0.1919 2.472 0.2887 2.569 0.3817 2.663 0.5939 2.887 0.5977 2.891 0.6829 2.983 0.7900 3.096 0.9276 3.255 0.9352 3.259 1.0000 3.337
C, HC1,-CCl, 0.0000 2.213 0.0121 2.220 0.0212 2.230 0.0245 2.237 0.0374 2.248 0.0702 2.284 0.1039 2.321 0.2194 2.425 0.3174 2.526 0.6132 2.856 0.7069 2.965 0.8142 3.101 0.9001 3.203 0.9558 3.281 1.0000 3.337
, ,
a
,
0.0002 0.0008 0.0002 0.0002 0.0004
a The values of refractive indexes of benzene, toluene, p-xylene, CCI,, CHCI,, and C,HCl, measured a t 303.15 K are 1.4940, 1.4900, 1.4895, 1.4530, 1.4393, and 1.4710, respectively. r
.. OV
-
e
(1,
4
e
ev
0
v ~
~
e
~
0
&
0
-0.04 -
B
UJ
a
- 0.06 -
-0.00
A A A , A
-
I
A I
I
I
B I
0
X
Flgure 1. Plot of the values of A€ vs. the mole fraction x of trlchloroethylene: ( 0 ) C2HCI,-benzene; C,HCI,-toluene; (A) C,HCI,-p-xylene; (0)C,HCI,-CCI,; (0)CpHCI,-CHC13.
(v)
(1)
where p refers to the density. The densities used to calculate k, for the various mixtures were obtained from the molal volumes of pure components and the measurements on excess volumes:!*3for the various systems. Results and Discussion The values of the dielectric constants for the various systems are given in Table I, whereas the values of the refractive indices, n12,for the various mixtures have been fitted to the empirical equation
+ (1- x)nz + x(1 - x ) A
.(n)
0.0072 0.0070 0.0062 0.00197 0.0087
00
chloroethylene (S. Rderck) of electronic grade were purified as described earlierS2 p-xylene (E. Merck) of synthesis quality was subjected to fractional crystallization, placed over anhydrous cdcium chloride overnight, and then fractionally distilled. The densities of the purified components, which were measured at 303.15 K, were found to be in good agreement with the values available in the l i t e r a t ~ r e . ~ ~ ~ Methods. ,The dielectric constants, which are accurate to fO.OO1, were measured a t 303.15 K and a t a frequency of 1.8 MHz/s, with a Dekameter (Type DKo3, Wissenschaftlish-Technische, Werkstatten, Germany), by using a cell (type MFL 1/S, Nr. 2078) of a capacity of ca. 10 cm3, as described earlieras Refractive index measurements were carried out by using a thermostated Abbe refractometer, a t 303.15 K. The values of the refractive indexes were obtained for sodium-D light. The ultrasonic velocities u were measured with a single crystal interferometer a t a frequency of 2 MHz/s. The adiabatic compressibilities, k,, were calculated from the relation0
n12= xnl
A
system C,HCl,-benzene C,HCl,-toluene C,HCl,-p-xylene C,HCl,-CCl, C,HCl,-CHCI ,
-0.02
x refers t o the mole fraction of C,HCI,.
k, = u-zp-1
TABLE 11: Valuesa of'the Constant A of Eq 2 and the Standard Deviations u (n) for the Various Systems at 303.1 5 K
(2) where nl and n2 are the refractive indices of components
1 and 2, respectively, A is a constant characteristic of a system, and x is the mole fraction of component 1. The values of the constant A for the various systems and the standard deviations, a(n), in the experimental values of n12from those obtained from eq 2 are given in Table 11. The values of the deviations, A€, in the dielectric constants of the various mixtures from the ideal volume fraction mixture law values have been plotted vs. x in Figure 1. It has been mentioned that dielectric Constants of polar mixtures can be represented as linear functions of the volume fraction,'O but Figure 1shows that the values of At are negative in the case of all of the present systems. The values of A€, though small and of comparable magnitudes in the case of the systems C2HC13-C6H6, C2HC13-toluene, C2HC13-CC14, and C2HC13-CHC13, are relatively larger in magnitude in the case of C2HC13-pxylene. The very small negative values of A€ may be attributed to the slight decreases in the degree of alignment of dipoles with changing composition of the mixture. The relatively more negative values of A€ in the case of the system CzHCl3-p-xylenecan be explained by the larger size of the p-xylene molecule, on account of which the p-xylene molecule will lead to greater changes in the degree of alignment of the trichloroethylene molecules, since the dispersion forces in pure liquids and their mixtures must be important in determining the dipolar configurations. In order to ascertain the degree of orientation of dipoles in the pure polar liquids and their binary mixtures, we have estimated the values of the Kirkwood correlation parameter, g, for toluene, CHC13, C2HC13, and binary mixtures of C2HC13with toluene and CHC13, for which the calculations were possible, using Frohlich's equationll
where k and N are respectively Boltzmann's constant and Avogadro's number, tois the permittivity of vacuum, V is
~
2168
The Journal of Physical Chemistry, Vol. 84, No. 17, 1980
the liquid molal volume, and pg represents the gas-phase dipole moment. The values of pg for toluene and CHC13, used in calculations of g from eq 3, were 0.37 and 1.03 D, respectively, as reported by McClellan,12 whereas the value 0.64 D of pg for C2HC13was obtained from the liquid-phase dipole moment of the component by using the formula given e1~ewhere.l~ For mixtures it was assumed that the appropriate values'of figin eq 3 are linear functions of mole fractions of components. The molal volumes of the mixtures used in eq 3 were estimated from the molal volumes of the pure components and the measurements on excess volumes2 for the various systems. The values of the refractive indexes for mixtures were estimated from the constant A given in Table 11. The values of g calculated from eq 3 in the case of binary mixtures of C2HC13with toluene and CHC13 are given in Table I, which shows that in the case of both of the systems the values of g increase in a systematic way with the increasing concentration of C2HC13. Though the value of pg for chloroform is higher than that for C2HC13,the value of g for the former is lower than that for the latter. The higher value of g for trichloroethylene and the increase in the values of g with increasing concentration of C2HC13in its binary mixtures with toluene and CHC13can be ascribed to a greater degree of alignment of dipoles of C2HC13molecules which have comparatively more linear-type character. In order to assess the perturbation caused to the polarity of the trichloroethylene molecule as a result of its interaction with CC14 and benzene, we have calculated the dipole moments of trichloroethylene in CC14 and benzene from the refractive index and the dielectric constant data for the dilute solutions of C2HC13in CC14 and benzene by using the method described by Halverstadt and K ~ m 1 e r . l ~ The values of the dipole moments of C2HC13have been found to be 0.87 and 0.91 D in CC14 and benzene, respectively. The value of the dipole moment of C2HC13in the liquid phase12 is 0.77 D. The values 0.87 and 0.91 D of the dipole moments of C2HC13in CC14 and C6H6have a change of 0.1 and 0.14 D, respectively, from the dipole moment 0.77 D of liquid C2HC13. This furnishes evidence in favor of the formation of electron donor-acceptor complexes of C2HC13with CC14and benqene in the liquid state. The values of u and k, for the various systems at 303.15 and 313.15 K are given in Table 111. The values of excess adiabatic compressibilities, k,E, which refer to the deviations of the values of k, (as obtained from eq 1)for mixtures, from the ideal volume fraction mixture law values, are also given in Table I11 and have been fitted by the method of least squares to eq 4,where B , C, and D are
k? = (P~(oz[B + C(CP~ - PJ + D(PI - ~ ~ 2 ) ' l
(4) constants characteristic of a system, and cp1 and cpz are the volume fractions of C2HC13and the second component, respectively. The values of the constants B, C, and D are given in Table IV. Table I11 shows that in the case of all of the systems of C2HC13with benzene, toluene, p-xylene, CC14,and CHC13 the values of Iz,E change either from positive to less positive or from positive to negative with the decrease in temperature. This can be explained by the increase in the strength of interaction between the components on account of the closer approach of the unlike species leading to reduction in compressibility and volume a t lower temperature. The various types of interactions that are operating between molecules in different systems are dispersion forces which should make a positive contribution to excess value of compressibility and charge-transfer, hydrogen-bonding, dipole-dipole, and dipole-induced dipole interactions which are expected to make negative
Nath and Dubey 1.2
I
-30
I
-20
I
-10
r
I
I
IO
I
20
I
30
1
40
I
I
50
60
P b.l:K
Figure 2. Plot of k: for equimolal mixtures at 303.15 K, vs. the difference, A bp (K), in the boiling points of the second component and C2HC13: (1) CpHC13-benzene; (2) CpHC13-toluene; (3) CzHC13-p-xylene; (4)CpHCI3-CCI4; (5) CpHCI,-CHCI,.
contributions. Dispersion forces are operative in all systems, and, for a system in which more than one type of interaction are present between the components, the excess compressibility would be the net result of the contributions from all types of interactions. Table I11 shows that k,E is either slightly positive, zero, or slightly negative in the various systems. This can be attributed to the existence of specific interaction between the components. The data show that for systems of C2HC13with aromatic hydrocarbons a t both of the temperatures k,E a t x = 0.5 has the sequence benzene > toluene > p-xylene This trend in the values of kSEfor the systems of C2HC13 with aromatics may be explained by increasing donoracceptor interaction of C2HC13with aromatics having an increasing number of CH3 substituents in the aromatic ring, since the addition of the CH3 substituent to the aromatic ring will increase the a-electron density of the molecule which will act as a a-type sacrificial electron donor toward C2HC13. The C2HC13molecule acts as a r-type sacrificial acceptor, on account of its reduced aelectron density due to the three C1 atoms directly attached to the ethylenic linkage. Thacker and Rowlinson,15Reddy et a1.,16 and Fort and Moore5 have used the difference in boiling points of components as a measure of the strength of interaction. In Figure 2, the values of k,E for equimolal mixtures have been plotted vs. the difference (Abp, K) in the boiling points of the second component and C2HC13 in the case of the various systems, and separate lines have been obtained for systems in which C2HC13can act as an electron donor and systems in which it can act as an electron acceptor. Although there is a likelihood for the formation of hydrogen bonding between the H atom of CHC1, and the a electrons of C2HC13,the C2HC13molecule, in its interaction with CC4, will act as a a-type sacrificial electron donor toward C C 4 which will act as a a-type electron acceptor. Figure 2 indicates again the increasing strength of interaction of C2HC1, with the aromatic hydrocarbons having an increasing number of CH3 groups attached to the ring, and this fact further becomes quite evident (see Figure 3) when we examine the plot of k,E vs. the excess volume2 VE for equimolal mixtures of C2HC13 with aromatic hydrocarbons at 303.15 K. Figure 3 shows that the excess volumes decrease as the number of CH3 substituents in the aromatic ring increases, and these changes in VE quantitatively parallel the excess compressibilities. In conclusion, it is to be pointed out that the present investigation reveals the existence of electron donor-acceptor interaction of C2HC13with aromatics and halomethanes, leading to the formation of complexes in solutions. The strength of the interaction of C2HC13 with aromatics increases with the increasing number of CH3 substituents in the aromatic ring, a fact which has been
The Journal of Physical Chemistfy, Voi. 84, No. 17, 1980 2109
Binary Systems of Trichloroethylene
TABLE 111: Ultrasoaic Velocities and Adiabatic Compressibilities for the Various Mixturesa of Trichloroethylene at 303.15 and 313.115 K temp = 313.15 K temp = 303.15 K 106k,, 1O6kSE, 106k,, 1O6hsE, X u , m s-' - atm-' atm-' X u , m s-' atm-' atm-' 0.0000 0.1112 0.2565 0.3679 0.5456 0.6064 0.7435 0.9459 1.0000
1276.4 1231.8 1183.7 1147.9 1102.2 1088.5 1060.1 1022.6 1013.7
71.7 71.6 71.2 71.2 70.4 70.1 69.4 68.3 68.0
0.0000 0.1256 0.2537 0.6721 0.7233 0.9395 1.0000
1282.8 1241.8 1200.1 1087.9 1075.9 1025.1 1013.7
71.8 71.3 71.1 69.4 69.1 68.4 68.0
C,HCl,-Benzene 0.0000 0.3 0.0875 0.5 0.3354 0.9 0.4154 0.7 0.5118 0.7 0.5749 0.5 0.7774 0.1 0.8277 0.8373 0.9023 1.0000
1240.4 1207.6 1125.4 1103.3 1078.3 1065.1 1021.8 1012.4 1012.2 1000.4 986.9
76.8 76.6 76.3 76.1 75.8 75.4 74.6 74.3 74.0 73.7 72.8
0.2 0.8 1.0 1.1 0.9 0.9 0.9 0.6 0.6
1244.0 12GG.6 1132.7 1110.4 1065.3 1049.3 1033.0 1003.2 986.9
77.2 76.8 75.9 75.6 75.0 74.4 74.0 73.2 72.8
0.1 0.1 0.2 0.4 0.1 0.1 0.0
1255.6 1227.6 1188.1 1166.1 1093.2 1074.7 1034.1 986.9
76.2 76.0 75.7 75.4 74.6 74.4 74.2 72.8
877.6 888.5 903.7 919.4 938.1 949.5 986.9
84.6 83.3 81.6 79.7 77.7 76.5 72.8
- 0.1
935.6 939.4 943.6 946.6 952.7 958.5 961.9 966.8 979.5 986.9
79.8 79.2 78.6 78.2 77.4 76.6 76.1 75.5 73.8 72.8
0.0 0.1 0.2 0.3 0.3 0.5 0.3 0.3
C,HCl,-Toluene 0.0000
0.0 0.2 0.0 -0.1 0.1
0.11 50 0.3687 0.4496 0.6287 0.7035 0.7781 0.9184
'.OOOO C,HCl,-p-Xylene
a
0.0000 0.21 37 0.2299 0.3990 0.57'17 0.6011 0.7 Ei98 1.0000
1288.8 1224.3 1223.0 ,1175.3 1124.6 1117.3 1075.2 1013.7
71.6 71.0 70.6 70.0 69.8 69.6 69.0 68.0
0.0000 0.1343 0.2258 0.3196 0.4385 0.6352 0.7258 0.8319 0.9439 1.0000
906.2 919.1 926.6 937.7 950.7 971.0 981.2 993.0 1006.5 1013.7
78.4 77.0 76.2 75.0 73.6 71.7 70.8 69.8 68.6 68.0
0.0000 0.2299 0.3399 0.4665 0.6863 0.7221 0.8367 0.9303 1.0000
968.4 978.6 983.6 988.8 1000.6 1002.2 1006.0 1011.7 1013.7
73.5 72.2 71.6 71.0 69.5 69.3 68.9 68.2 68.0
0.0 - 0.3 - 0.4 0.0 - 0.1 - 0.1
0.0000 0.0944 0.2292 0.3081 0.5761 0.6459 0.7934 1.0000
C,HCl,-Carbon Tetrachloride 0.0000 0.0 0.1251 0.0 0.2910 -0.2 0.4296 -0.5 0.6082 -0.3 0.7003 - 0.2 1.0000
0.1 0.1 0.0 0.1 0.1 0.5
0.1
Q. 3 0.1 0.0
0.0 0.0
C,HCl,-Chloroform 0.0000 0.1 0.0741 0.1 0.1725 0.2 0.2346 -0.1 0.3579 - 0.2 0.4716 0.1 0.5614 - 0.1 0.6378 0.8952 1.0000
x refers to the mole fraction of C,HCl,.
TABLE IV: Values of the Constants ByCy and D of Eq 4 for the Various Systems at 303.15 and 313.15 K system temp, K 106B, atm-' 106C,atm-' 106D, atm-' C,HCl,-benzene 303.15 3.1175 - 0.4930 - 0.9433 313.15 4.0248 2.1085 0.5794 1.7164 303.1 5 C,I1Cl,-toluene -0.2084 0.2305 " 313.15 0.9183 - 0.4701 -0.6329 C,HCl,-p-xylene 303.15 0.9974 0.3673 -0.6547 313.15 0.1844 2.611 3 4.91 58 C,HCl,-carbon tetrachloride 303.15 2.6115 - 1.4599 -0.2020 313.15 -1.6817 0.6382 -1.9255 C,HCI ,-chloroform 303.15 -0.9831 0.3842 - 0.8262 1.4164 1.7827 0.5950 313.15
2170
J. Phys. Chem. 1980, 84, 2170-2179
between CC1, and C2HC13has been indicated.
0’4v
0.2
-0.4
t
-0 6L
Figure 3. Plot of k: vs. VE for equimolal mixtures at 303.15 K: (1) C2HCi3-benzene; (2) C,HCi,-toluene; (3) C,HCI,-p-xylene.
attributed to the increased n-electron density of the aromatic molecule which will act as a .ir-type sacrificial electron donor toward C2HC1,. The possibility of formation of donor-acceptor complexes due to hydrogen bonding between CHC13 and C2HCl, and due to 0-r interaction
Acknowledgment. We are grateful to Professor R. P. Rastogi, Head of the Chemistry Department, Gorakhpur University, for encouragement during the present investigation. Thanks are also due to the University Grants Commission, New Delhi, for financial support.
References and Notes (1) Currently with Chemistry Department, N. D. College, Barhaiganj, Gorakhpur. (2) J. Nath and S. N. Dubey, J . Chem. Thermodyn., 11, 1163 (1979). (3) J. Nath and S. N. Dubey, J. Chem. Thermodyn., in press. (4) J. G. Kirkwood, J. Chem. Phys., 7,911 (1939). (5) R. J. Fort and W. R. Moore, Trans. Faraday Soc., 61,2102 (1965). (6)J. Timmermans, “Physico-Chemical Constants of Pure Organic Compounds”, Eisevier, Amsterdam, 1950. (7) A. Weissberger, E. S. Proskauer, J. A. Riddick, and E. E. Toops, Jr., “Technique of Organic Chemistry”, Voi. VII, Interscience, New York, 1955. (8) R. P. Rastogi and J. Nath, Indian J. Chem., 5, 249 (1967). (9) K. S.Reddy and P. R. Naidu, J. Chem. Thermodyn., 8, 1208 (1976). ( I O ) T. B. Hoover, J . Phys. Chem., 73,57 (1969). (11) N. E. Hili, W. E. Vaughan, A. H. Price, and M. Davies, “Dielectric Properties and Molecular Behaviour”, Van Nostrand-Reinhold, London, 1969, p 31. (12) A. L. McCieiian, “Tables of Experimental Dipole Moments”, W. H. Freeman, San Francisco, 1963. (13) See ref 11, p 30. (14) I. F. Haiverstadt and W. D. Kumier, J . Am. Chem. Soc., 64,2988 (1942). (15) R. Thacker and J. S. Rowlinson, J . Chem. Phys., 21,2242 (1953). (16) K. C. Reddy, S. V. Subrahmanyam, and J. Bhimasenachar, Trans. Faraday Soc., 58, 2352 (1962).
Methylamine-Deuterium Isotope Exchange Equilibria in the Gaseous and Liquid Phases J. H. Rotston,” J. den Hartog, J. P. Butler, Atomlc Energy of Canada Limited, Research Company, Chalk River Nuclear Laboratories, Physical Chemistry Branch, Chalk River, Ontario KOJ IJO, Canada
L. Silberrlng, and Hs. H. Gunthard Physical Chemistry Laboratory, Swiss Federal Institute of Technology, ETHZ-Zentrum, 8092 Zurich, Switzerland (Received: September IO, 1979; I n Final Form: March 7, 1980) Publication costs assisted by Atomic Energy of Canada Limited and Swiss Federal Institute of Technology
The deuterium-protium separation factor, a, between molecular hydrogen and liquid methylamine in the presence of potassium methylamide catalyst has been measured at low deuterium concentrations over the temperature range -50 to +5 “C. The separation factor is about 10% larger than that for liquid ammonia, and its dependence upon absolute temperature, T , is given by In a = 0.1135 + (240.05/T) + (43989/p). The equilibrium constant, K1, for deuterium-protium exchange between hydrogen and the amino group of methylamine vapor has been calculated for all deuterium concentrations at temperatures between 150 and 400 K with partition functions for methylamine derived from an internal rotation-inversion-normal vibration model of methylamine based on spectroscopic data. Conversion of K1 into a values, by inclusion of vapor-liquid fractionation effects, shows that the discrepancy between theory and experiment is less than the combined tolerances (&5%)of the two approaches. The dependence of on deuterium atom fraction is discussed. (Y
1. Introduction A precise determination of the overall deuterium-protium separation factor, a , between hydrogen and liquid methylamine is required to critically evaluate the economics of a proposed bithermal process for the extraction of deuterium from hydrogen streams.1,2 The magnitude of a is primarily governed by the equilibrium isotope effect on the deuterium distribution between hydrogen and the 0022-3654/80/2084-2170$0 1.OO/O
amino group of methylamine vapor and to a lesser extent on the fractionation effect arising through the different volatilities of protio- and N-deuteriomethylamines. At low deuterium concentrations the isotope distribution in the gas phase is governed by the equilibrium constant, K1, for the exchange between methylamine vapor (v) and hydrogen gas (8) (eq 1). CH~NH,(V)+ HD(g) + CH,NHD(V) + H2(g) (1) 0 1980 American Chemical Society
