July, 1947
CONDUCTANCE OF SALTS M N I T R O ~ Z E N E
1731
mide. At 340" a reaction occurred, and 28 8. of yellow. s u m q liquid was obtained w e r a period of seventy-two hours. 1. A general reaction of h y d r d a halides The major part of Ws liquid distilled over the range of 148 to 208'. Trimethylgermanium bromide is the only with elementary germanium to proaclGe &e mmethyfgermanium brolnide which has been described,' and its boiling point is 113.7'. The reaction product SPOnd 2. therefore appears t o contain dimethylgermanium dibromide and methylgermanium tribromide, and isolation of nium of metalllc copper as a catalyst. these new compounds is planned.
3. The new compounds dirnethflgemaaium From these four examples, it appears that the reaction of hydrocarbon halides with elementary dichloride (b.p. 1 2 4 O , m. p. -22', d. 1.492 a t 20' germanium is a general one in which any such and 1.488 at 2 6 O , n 1.4552 at 29') and methylhalide may react under specific conditions of tem- germanium trichloride (b. p. 11l0,d. 1.73at 24.5') perature and catalysis to yield the corresponding are described as products of the above reaction. SCHENECTADY, NEWYoRECEIVED MARCH 24,1947 organogermanium halides.
[CONTRIBUTION FROM THE
METCALF RESEARCH LABORATORY OF BROWN UNIVERSITY]
Properties of Electrolytic Solutions. XXVIII. Conductance of Some Salts in Nitrobenzene at 2S01 BY EDWARD G. TAYLOR~ AND CHARLES A. b u s I. Introduction Conductance measurementsin ethylene chloride have provided us with much information concerning the influence of specific constitutional factors upon the interactions of ions in a solvent medium of relatively low dielectric constant. Nitrobenzene is a solvent of moderately high dielectric constant, the molecules of which, like those of ethylene chloride, contain no active hydrogen atoms and lack basic properties. Nitrobenzene has a low vapor pressure and is easily obtained in a high state of purity. It is thus suitable for accurate conductance measurements. On account of its relatively high dielectric constant, it has been possible to obtain accurate values for the limiting coaductawe and dissociation constaqt of salts which are tqm weak to permit of accurate evaluation in ethylene d o r i d e . Moreover, a number of salts of inorganic cations are sdiciently soluble to permit of measurement. The dissociation constants of the strongest salts cannot be accurately evaluated because of their almost complete dissociation. The influence of cationic size on the characteristic constants of electrolytes has been investigated by measurements with a series of homologous tetra-alkylammonium picrates. In order to ascertain the effect of substituting ethyl, hydrogen, hydroxyl, methow and phenyl, respectively, for one of the methyl groups in the tetmmethylamraonium ion, the picrates of ethyltrimethylammomiurn, trimethylammonium, trimethylhydroxpmmonium, trimethylmethoxy(1) This p a p a comprises part of the subject matter of a thesis submitted by Edward G . Taylor in partial fulfillment of the requirernCatBfo0 the w e e of Mester of Sdence in the Graduate School of B t b m u k o i v d t ~ ;May, 1S8. ($4) Cohrmonmplth Fellow a t Brown University, 1986-1037, lW-l$W Present address: W i l I i ~ sCollege, Williamstown, Mass.
ammonium and phenyltrimethylammonium have been studied. Choline picrate and bromomethyltrimethylammonium picrate have been empbyed to study the effect of replacing an alkyl hydrogen atom by hydroxyl and bromine, respectively. Methoxymethyltrimethylammonium picrate, aa isomer of choline picrate, phenyldim&yIhydroxpmmonium picrate and phenyldirnethylammonium picrate have also been investigated. For the purpose of determining ion conduetances, measurements were subsequently carried out by Mr. M. B. Reynolds, of This Laboratory, with tetrabutylammonium triphenylboro3uoride. The results of these measurements are included in this paper.
II. Experimental Apparatus.-Details of the measuring apparatus have been fully d e s m i d in earlier papers of this Scries. The conductance cells were of the type described b y Cox, &us and Fuass.8 They were provided with bright piatinum elec?trodes.
Materieis.-Nitrobenzne" was fractionally frozen three times, about one-third of the total being poured off as a liquid each time. It was then washed successively with sulfuric k i d ( l : l ) ,water and sodium hyboxide. The treatment with caustic was continued until the washings were no longer colored. After thoroughly washing with water, the nitrobenzene was dried over calcium chloride. The filtered liquid was fractionated twice under low pressure (€2 mm.). The pale yellow fracticpn was allowed to stand over powdered barium oxide, filtered and again fractionated (under reduced pressure), this time from activated aluminum oxide. Following the above procedure, solvent having a specific conductance of 2-4 X 10-10 was readily obtained. The following tetraalkylammonium picrates were prepared and purified by the usual methods: tetramethylammonium picrate, m. p. 318-319"; ethyltrimethylammonium picrate, m. p. 307-308" (dec.) ; tetraethylam(3) Cox, Kraus and Fuoss, Trans. Faradoy Soc., ti, 740 (1QU). (3a) Oil of Mirbane, kindly donated by the Cako ChemMl Com-
pany, of Bound Brook. New Jersey.
EDWARD G.TAYLOR AND CHARLES A. KRAUS
1732
monium picrate, m. p. 35&6'; tetra-n-propylammonium tetra-n-butylammonium picpicrate, m. p. 115-116.5'; rate, m. p. 8g.5*; and t&rar-pmglammonium picrate, rn. p. 74ib74*6b. picrate wa?l prepared by the 4 daoxide with picric gydroxide is readily .@de on trimethylamiine in aqueous solution a t room tapera-. The picrete was w s t d k d from alcohol-water mixtures, m. p: 207-208". Tnmethylmethoxyammonium iodide was prepared by the interaction of methyl iodide with a d i d hydrate of trimethy&ydroxyamm&um hydroxide in m e w 1 akohol solution. The hydroxide was prepwed by waporation of its aqueous solution in wcuo over calcium chloride and phosphorus pentoxide, m. p. 80-70". The methoxytrkthylammonium iodide was metathesized with silver picrate in aqueous solution. The picrate was recrystallized from aqueous alcohol and also from alcohol, m. p. 219'. Phenyldimethythydroxyammonium picrate was obtained by the interaction of picric acid with dimethylsIiiline oxide. The latter was p r m e d by the oxidation of dimethylaniline with hydrogen peroxide.' The picrate was recrystallized from alcohol, m. p. 139' (dec.). Phenyldimethylammonium picrate was recrystallized from alcohol-water mixtures and also from acetone, m. p. 160 Trimethylammonium picrate was recrystallized from alcohol, m. p. 223'. Phenyltrimethylammonium picrate was prepared from It was recrystallied from the corresponding bromi?. alcohol, m. p. 122.6-123 Bromomethyltrimethylammon~tun picrate, m. p. 236' ; choline picrate, m. p. 247-247.5'; and omethoxymethyltrimethylammonium picrate, m. p. 200 , were products of this Laboratory. The bromo compound was further purified by reerySeallEzation from water while the other two &ts were recrystallid from alcohol. Tetra-%-butylarnmoniumtriphenylbwduoride was prepared by Mr. G. L. Brown by the method of Fowler.' It was dissolved in sufficient hot alcohol to put it into solu$on; crystals were obtained upon cooling, m. p. 165-
".
.
166
.
All salts war4 dried by long standing in vacuo over phosphorus pentoxide a t room temperatures.
TABLE I CONDUCTANCE OF S o n SUBSTITUTED AMMONIUM SALTS IN NITROf3BNZSNE AT 25 " c x 10' A c x 104 A Tetramethylammonium picrate
50.80 18.83 7.846 3.498 1.475 0.5152 .1555
26.85 29.38 30.87 31.75 32.36 32.80 33.11
Tetra-n-propylammonium picrate
35.74 14.38 5.916 2.535 1.062 0.4418 .1936
25.28 26.77 27.74 28.36 28.75 29.02 29.21
Tetraethylammonium picrate
39.47 14.00 5.901 2.431 1.034 0.3937 .1164
27.81 29.60 30.60 31.27 31.68 31.98 32.21
Tetra-n-butylammonium picrate
28.69 11.89 5.187 2.323 1.069 0.4589 .1972
24.25 25.49 26.29 26.81 27.15 27.41 27.58
f4) Bambecger and Tsei~ienrar,Bur., 88.846 (leeo). (51 Fowler and Kraus. THISJ O W ~ A L , a, 1148 (1840).
Tetra-n-amylammoniurn picrate
23.98 10.77 5.371 2.660 1.293 0.5982 .2714
23.49 24.54 25.19 25.66 26 ..OO 26.24 26.43
Phenyltrimethylammonium picrate
39.07 15.96 6.854 2.678 0.8550
.2195
26.08 28.13 29.42 30.32 30.95 31.32
Hydroxyethyltrimethylammonium picrate
37.33 15.80 7.053 3.089 1.387 0.5580 .2026
Vol. 69 Tetra-n-butylammonium triphenylbomfluoride
25.31 9.653 3.209 1.752 0.7689
Ethyltrimethylammonium picrate
39177 17.26 7.425 3.231 1.438 0.6214 * 2280
35.95 14.27 5.635 2.157 0.7123 .2343
22.31 25.87 28.36 30.02 30.99 31.63 32.03
43.29 17.50 8.016 3.760 1.802 0.7591 .3178
35.33 15.63 7.501 3.740 1.854 0.9591 .4301
27.69 29.80 31.12 31.99 32.58 32.97 33.30
Phenyldimethylhydroxyammonium picrate
33.13 14.48 6.883 3.025 1.230 0.4850 .1828
2.177 3.292 4.688 6.554 8.960 12.64 17.19
2.381 3.389 4.646 6.538 9.345 13.13 17.86
Phenyldimethylammonium picrate
Trimethylammonium picrate
44.35 18.47 8.974 4.186 1.762 0.6802 .2364
24.49 ,27.53 29.55 30.78 31.52 31.92
Trimethylmethoxyammonium picrate
26.62 29.28 31.07 32.07 32.68 32.95
Trimethylhydroxyammonium picrate
27.77' 29.66 30.98 31.82 32.35 32.71 33.00
Bromomethyltrimethylammonium picrate
Methoxymethyltrimethylammonium picrate
43.53. 15.89 5.348 1.. 770 0.5237 .1303
20.37 21.55 22.33 22.63 22.90
36.35 13.73 5.288 2.089 0.7605 .2659
6.086 8.849 11.844 15.70 20.67 26.05 30.65
2.893 4.141 5.536 6.830 7.932 8.827
Procedure.-The dilution method as described in earlier papers was adopted. Corrections for solvent in the vapor phase were negligible and vacuum corrections were unnwestmy. All measurements yere made in an oil thermostat mslntained a t 25 * 0.01
.
CONDUCTANCE OF SALTS IN NITROFBNZENFC
July, 1947
In no instance was there any appreciable change of resistance with time- The dts were recrystallized until concordant results (@.l%) were obtained with samples from two consecutive reuystalifzations.
m. Rmdts
1733
plot m &e F/A-axis, the d u e d Itb is obtained and from the slope d che fit, t&evahof ttredlissociation constaslt, K, may be wa&&d. A number of typical plats are 3 h v k in Pig.@; the steeper the plot, the lower is the value of K.
Values of the equivalent conductance, A, and the concentration, C, in gram equivalents per liter of solvent, me given in Table I. The densities of the solutions have been taken to be the same as that of the pure solvent, 1.1986.6 Although two independent series of measurements were made with each salt, the results of only one series are recorded here.
IV. Discussion Electrolytes having very large ions conform closely to the Debye-Hiickel-Onsager equation' in nitrobenzene. Assuming 0.01811 for the viscosityd and 34.5 for the dielectric constants at 2 5 O , the,Onsager equation becomes A =
- (0.784ho + 44.6)C
