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HAROLD L.
PICKERING AND CHARLES
ing lines from the normal to the enlarged partial diagram and vice versa. Application to other Four-Component Systems.-The methods described above can be applied to systems composed of water and three salts with a common ion if the following method of plotting is followed. The figure appears in an equilateral triangular graph with vertices A, B and C and point of intersection of perpendiculars from these vertices to their opposite bases, 0. Then a point is determined by plotting the mole fractions of salts A and B as coordinates along the axes OA and OB originating a t the center 0. The point is then moved parallel to the third axis OC, a distance equal to mole fraction of salt
c.
[CONTRIBUTION FROM THE
Vol. 71
A. -US
Acknowledgment.-The author wishes to thank Professor J. J. Beaver for his constructive criticism of this paper. Summary A two-dimensional, quaternary phase diagram is presented in which compositions are described in all four constituents and in which graphical solutions to general phase separation problems may be made. The diagram is constructed by superimposing an orthogonal projection of a three dimensional Schreinemakers diagram upon a Jaenecke projection in such a way that the method of wet residues may be applied. NEWYORK,N. Y.
RECEIVED NOVEMBER 7, 1947
METCALF RESEARCH LABORATORY, BROWN UNIVERSITY]
Properties of Electrolytic Solutions. XLIV. Conductance of Some Long Chain Salts in Ethylene Chloride, Pyridine and Nitrobenzene at 2501 BY
HAROLD L.
PICKERING'
I. Introduction Weaver3 has measured the conductance of several long chain salts in ethylene chloride and nitrobenzene. In these solvents the salts behaved like normal electrolytes. It seemed worth while, therefore, to measure the conductance of a larger number of long chain salts. It was of particular interest to determine the limiting conductance of long chain ions and to find how the conductance of such ions depends on the number of carbon atoms that they contain, on the one hand, and their arrangement about the central nitrogen atom, on the other. To this end, the conductance of a number of long chain salts was measured in ethylene chloride, pyridine and nitrobenzene. In addition, the conductance of several ordinary quaternary ammonium salts was determined in order to fill gaps in the list of ion conductances. 11. Experimental Salts.-These were prepared according to conventional methods. It is important to use only well purified starting materials. Nitrates and picrates were prepared by metathesis of iodides with silver salts in methanol or ethanol. The following salts were prepared: (1) n-octadecylpyridonium nitrate (m. p., 79-80'), (2) di-n-octadecyldimethylarnmonium picrate (m. p., 75.5-76.2 ") , (3) di-n-octadecyldi-n-butylammonium picrate (m. p . 50.551.5"), (4) n-octadecyltri-n-butylammonium nitrate (m. p., 90.5-91.5'), (5) n-octadecyltri-n-butylammonium picrate (m. p., 42-43 O ) , ( 6 ) n-octadecyltrimethylammonium iodide (m. p., 237-238.5'), (7) n-octadecyltrimethyl1.
(1) This paper is based on a portion of a thesis presented by Harold L. Pickering in partial fulfilment o f the requirements for the Degree of Doctor of Philosophy in the Graduate School of Brown University, August, 1947. (2) National Research Council Fellow, Brown University, 19461947. Present address: Research Laboratory, Stanolind Oil and Gas Company, Tulsa, Oklahoma. (3) Weaver and Rraus, THIS JOURNAL, TO, 1707 (1948).
AND CHARLES
A. KRAUS
ammonium picrate (m. p., 134-135"), (8) n-propylpyridonium picrate (61-62"), (9) tetra-n-butylammonium picrate (m. p., 73.5-74.5"), (10) tetra-n-propylammonium picrate (m. p., 115-116'). Earlier preparations of tetran-butylammonium triphenylborofluoride (11) and formate (12) were measured after several recrystallizations. The salts were recrystallized as follows : (1) hexane plus few drops of ethanol, (2) hot absolute ethanol, (3), (5) methanol plus few drops of ethanol, (4) dioxane-water followed by hexane-ethanol, (6), (7) absolute ethanol, (8) 99% ethanol, (Q), (lo), (12) 95% ethanol, (11) ethanol plus 10% hexane. 2. Solvents.-Solvents were prepared as described in earlier papers.4 Solvent resistances were measured with a special parallel arm bridge permitting of precise measurements up to 107 ohms. 3. Apparatus and Procedure.-These were the same as those described in earlier papers of this ~ e r i e s . ~
111. Results In Table I are given equivalent conductances a t different concentrations (expressed in moles per liter of solution) for several salts in ethylene chloride. Similar data are given for solutions in pyridine in Table I1 and for solutions in nitrobenzene in Table 111. All measurements were carried out a t 25 * 0.01'. In computations, the following values were employed for physical constants. Ethylene chloride Pyridine Nitrobenzene
Density
Viscosity
Diel. const.
1.2455 0.97792 1.1986
0.00787 .008824 .om1
10.23 12.01 34.5
IV. Discussion Ethylene Chloride and Pyridine.-The data of Table I for ethylene chloride and those of Table 111, for pyridine, have been analyzed 1.
(4) (a) Mead, Fuoss and Kraus, Trans. Faraday SOC., 33, 594 (1938), ethylene chloride; (b) Witschonke and Kraus, THIS JOURNAL, 68, 2472 (1947),nitrobenzene; (c) Carignan and Kraus, i b i d . , 71, 2983 (1949),pyridine.
TABLE I CONDUCTANCE OF SOME QUATERNARY AMMONIUMSALTS IN ETHYLENECHLORIDE
cx
10'
A
cx
104
A
B. Di-n-octadecyldimethylammonium picrate 12.79 12.92 3,059 20.75 23.50 2.034 1.250 26.95 0.8192 30.01 34.25 .4463 ,2192 38.60 ,1227 41.40 C. Di-n-octadecyldi-nD. N-Octadecyltri-nbutylammonium picrate butylammonium nitrate 14.64 19.35 22.96 16.83 3.218 28.23 3.649 28.95 2.109 30.87 2.440 32.24 1.488 32.99 1.529 36.17 0 9060 35.78 0.7387 42.05 .5696 38.08 .4271 46.03 .2881 40.79 .2328 49.65 .1436 42.75 ,09721 53.42 E. N-Octadecyltrimethyl- F. N-Octadecyltrimethylammonium formate ammonium iodide 22.99 3.323 13.915 8.893 3.871 14.54 4.044 6.962 2.436 17.19 2.271 8.930 1.643 19.73 1.669 10.20 1.118 22.45 1.165 11.89 0.8038 24.91 0,7884 14.00 .4420 29.88 .4940 16.93 .2293 22.80 .1769 37.91 .1655 25.62 H. N-Propylpyridonium G. N-Octadecyltrimethylammonium picrate picrate 17.34 10.96 37.63 11.13 23.37 18.70 4,471 3.840 22.59 2.805 27.42 2.193 25.00 1.806 31.67 1.597 1.200 27.29 1.017 37.74 0.8274 30.37 0.6386 42.88 .5738 34.15 .3482 49.51 .2101 54.63 .1350 58.49 TABLE I1 CONDUCTANCE OF SOMEQUATERNARY AMMONIUMSALTS I N NITROBENZENE A. N-Octadecylpyridonium nitrate 29.25 6.728 15.53 3.359 19.70 1.804 26.49 0.7853 .4071 32.70 39.78 .2027 45.88 ,1070
cx A.
104
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CONDUCTANCE OF LONGC H A ISALTS ~ IN ETHYLENE CHLORIDE
Oct., 1949
A
N-Octadecyltrimethylammonium picrate 23.59 22.80 10.42 24.05 4.459 24.92 2.402 25.36 1.669 25.57 0.8075 25.87 .3536 26.09 2060 26.16
cx
104
A
B. N-octadecyltri-n-butylammonium picrate 18.43 21.83 9.397 22.59 4.472 23.23 2.264 23.63 1.156 23.91 0.5718 24.11 .3041 24.30 .1411 24.43
C. Di-n-octadecyldimethylammonium picrate 20.78 20.65 9.645 21.66 4.909 22.29 2.355 22.78 1.194 23.07 0.6244 23.30 .3219 23.45 .1530 23.56
D. Di-n-octadecyldi-nbutylammonium picrate 30.54 19.85 10.24 21.20 5.767 21.70 3.710 22.00 2,309 22.26 1,452 22.46 0.9777 22.60 .6178 22.74 .3129 22.84 .1601 22.94
E. Tetra-n-butylammonium triphenylborofluoride 21.91 20.79 21.70 10.59 5.795 22.23 22.71 2.848 1.291 23.07 0.7723 23.24 .3428 23.42 .1518 23.63
F. N-Octadecylpyridonium nitrate 53.21 26.10 12.79 6.618 3.255 2.119 1.021 0.5094 .2037
23.04 26.07 28.40 29.97 31.16 31.64 32.31 32.73 33.10
TABLE I11 CONDUCTANCE OF SOMEQUATERNARY AMMONIUMSALTS IN PYRIDINE
cx
104
A
A. N-Octadecyltri-nbutylammonium picrate 4.474 38.18 2.278 41.66 1.444 43.62 0.8643 45.46 .4114 47.47 .1768 48.92
cx
104
A
B. Tetra-n-amylammonium picrate 4.243 41.78 2.355 45.07 1.232 48.09 0.6791 50.27 .3348 52.08 .2150 52.97
D. TetraethylC. Tetra-n-propylammonium picrate ammonium picrate" 5.6119 53.66 2.913 49.76 1.884 52.21 2.6677 59.17 1.104 54.72 1.6327 62.34 0.6816 56.55 0.77968 66.09 0.43674 68.27 .5040 57.48 0,21450 70.35 ,1912 59.56 Measurements by Dr. C. J. Carignan.
by the method of Fuoss5 and values of the limiting conductance, ho,and the dissociation constant, K , have been obtained. These values are collected in Table IV, where limiting conductances are given in column 2, cation conductances as determined by the method of Fowler5 in column 3 and dissociation constants in column 4. In Figs, 1 and 2 are shown Fuoss plots for several salts in ethylene chloride and pyridine, respectively. As may be seen from the figures, the salts measured in ethylene chloride and pyridine conform to the Fuoss relation within the limit of experimental error, and successive series are in good agreement. (5) (a) Burgess and Kraus, THISJOURNAL, TO, 706 (1948); (b) Fowler and Kraus, ibid., 63, 2237 (1940).
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HAROLD L. PICKERING .AND CHARLES A. KRAUS
Vol. 71
The dissociation constants of the homologous series of quaternary ammonium picrates in ethylene chloride increase regularly with increasing 10' numbers of carbon atoms in the substituent groups as Tucker has shown.6 In this connection, i t is of interest to note that the constant for OctdMesNPi 54.91 23.7 47.73 16.5 0'49 dioctadecyldibutylammonium picrate is 2.61 X OctdlMezNPi 57.90 17.8 0'78 as against 2.38 X lod4 for tetra-n-amylarnOctdBuaNNOa 46.13 14.9 ''I2 monium picrate. The constant for tetraethylamOctdeBuzNPi 62.77 22.7 2'61 0.21 monium picrate is 1.59 X lo-*. OctdPydNOn In contrast to the regular change of the dissociaPrPydPi 71.84 40.6 .49 .28 tion constant of the quaternary ammonium picOctdMe8NI 53.6 29.9" OctdMerOCHO 60.24 36.5" 049 rates in ethylene chloride, in pyridine the constant changes but little and, seemingly, irregularly. Iodide and formate ions As may be seen from Table 11, b, the constant for B. Pyridine tetraethylammonium picrate is 10.4 X lo-' while OctdBusNPi 50.79 17.1 12.0 that for tetrabutylammonium picrate is 12.8 X Octd~BulNPi" 47.03 13.3 10.1 But the constant for tetra-n-amylammoAm,NPi 55.28 21.6 11.3 nium picrate is only 11.3 X and that for diPr4NPi 62.11 28.4 11.2 octadecyldibutylammonium picrate is 12.0 X EtrNPi 73.31 39.6 10.4 It is of interest to note that while in ethylPrivately communicated by Mr. E. J. Bair, of This ene chloride the constant for tetra-amylammonium picrate is 7.4 times that of the corresponding Laboratory. tetramethylammonium salt, in pyridine the conIn ethylene chloride, the iodide and formate stants for the same two salts have a ratio of only ions have rather low conductances; this is partic- 1.7. It is evident that the effect of chain length ularly true of the iodide. It is a striking fact that, on the interaction of quaternary ions with the in this solvent, the conductances of the chloride, picrate ion in pyridine differs greatly from that in bromide and iodide ions differ widely, being, re- ethylene chloride. Whether the inversions found spectively, 39.1, 33.8 and 29.9. The conductance for the constants in pyridine are real or a result of of the iodide is 2370 less than that of the chloride experimental error remains uncertain as yet. ion. Luder's conductance values for tetrabutylammonium picrate have subsequently been twice checked and confirmed independently. The symmetrical quaternary ammonium salts used in this investigation were the same as those used earlier by 50 Tucker' except for their recrystallization. 2. Nitrobenzene.-Strong salts (i. e., salts of large ions) are so highly dissoP ciated in nitrobenzene that their dissoX ciation constants cannot be evaluated. 4 Values of A. may be determined by ex2 30 trapolation of A-
