SOLUBITJTY OF TAPHTH.4LENE IN ALCOHOLS
685
2. During the thixotropic liquefaction there is no pH change within the limits of experimental error in the cases of a thorium molybdate, a ferric hydroxide, and a bentonite gel. 3. During the secondary gelation there is no change in pH within the limits of experimental error in the cases of a thorium molybdate, a ferric hydroxide, and R bentonite s>-steni. REFERESCES (1) BATCIIELOR, H. 5V.: J. Phys. Chcm. 42, 575 (1938). (2) BROUGISTON, G., A N D SQUIRES, L.: J. Phys. Chem. 40,1041 (1936). ( 3 ) FREUNDLICH, H.: Thirotropy, Actualit& scientifiques et industrielles, S o . 267 (1935). (4) G o o n E m , C. F.: Trans. Faraday SOC.36, 342 (1939). (5) HCRD,C. B., ASD GRIFFETH,R. L.: J. Phys. Chem. 39, 1155 (1935). (6) NCDOWELL, C. bl.,A N D USHER,F. L.: Proc. Roy. Soc. (London) A131, 564 (1931). (7) PRIKISH, s.: IColloid-2. 64, 293 (1933). (8) I’R.’IIL~SH, S.,.IXD DHAR,K. R.:J. Indian Chem. SOC.6, 391 (1929). (9) PRASAD, RI., AND DESAI,D. M.:J. Univ. Bombay 2, S O .7 , Part 3, 132 (1938), (10) P R ~ S A M., D , A N D HATTL~NGADI, R. R.: J. Indian Chem. SOC.6, 893 (1929) (11) USHER,F. L.: Proc. Roy. SOC.(London) A126, 113 (1929).
T H E SOLUBILITT OF SAPHTHALEKE IN AQUEOLS YOLUTIOSS OF NETHAXOI,, ETHAKOL, 1-PROPASOL, AND 1-BGTAKOL AT SEVERAL TEMPERATURES OTTO \Ir. MANNHARDT,‘ ROBERT E. D E RIGHT: WILFRID H. M14RTIN,J CHESTER F. BURMASTER,a AND WILLARD F. W.4DT4
Department of Chemistry, The University of Rochester, Rochester, New Y O T ~ Received April 14, 1948
In another research carried out in this laboratory (8) the solubility of naphthalene was determined in methanol, ethanol, 1-propanol, and 1-butanol (along with isomers of the last two) at several temperatures, and the effect of vvatcr on the solubility was determined for methanol and ethanol in the vicinity of 50’C. These last two experiments yielded results which indicated that further work was desirable; accordingly, very shortly thereafter about thirty runs were made on four different aqueous solutions of ethanol. -4n indication of a solubility gap was encountered with the solution containing about 82 per cent ethanol, and s.hundant evidence of such a gap was found for the 72 per cent ethanol solution. Further work seemed desirable uith ethanol, and it also appeared of interest t o study the other aliphatic alcohols mentioned above from this and other points Present address: E. I. du Pont de Nemours and Company, Ino., Buffalo, New York. E. I. du Pont de Nemours and Company, Inc., Wilmington, Delaware. a Present address: Eastman Kodak Company, Rochester, New York. 4 Present address: Standard Oil Company of New Jersey, Bayonne, New Jersey. 1
* Present address:
686
MANNHARDT, DE RIQHT, MARTIN, BURMASTER AND WADT
of view. Specific parts of the problem were then assigned to each of the present authors. At the time this work was undertaken6 the only results which could be found on these ternary systems wcre those of Miss Christiansen (2). For both methanol and ethanol she reported isotherms at 0" and 25'C., and for I-propanol a single6 isotherm a t 2 5 T . No experimental work could be found on the ternary system involving 1-butanol. It has been found necessary t o discontinue this work ; hence, although there is much ground still to be covered and some points to be investigated more carefully, it seems desirable to place on record what has been done t,lius far. The present paper is accordingly concerned only with the upper or, within the solubility gap, the two upper transformations in these systems and, when taken along with published data on the respective contiguous binary systems, gives a fairly good idea of the nature of the ternary ditectic surface, the line of three-phase monotectic equilibrium (and the corresponding tie lines or ruled surface), and the ternary dichortic surface. As far as these researches go, it appears that these systems conform to type XI11 discussed by Marsh (5), but with 1-butanol it would be expected that with compositions richer in water and less rich in naphthalene another solubilit,y gap mould be encountered. MATERIALS, APPARATC'S, AND PROCEDURE
The naphthalene was purified as described in earlier papers from this laboratory (8,9). Since the conclusion of this work, Ward (11) has reported a melting point of 80.25-80.3'C. for a sample of naphthalene purified with great care; this is 0.13" to 0.18"C. higher than tJhemelting point of the samples used in the present research. It is felt, however, t'hat the solubility results would be influenced very little if a t all by any small impurities in the solute. The methanol and 1-propanol samples had been carefully preserved from the earlier research and were used without further treatment; the ethanol used in a considerable portion of the runs was from the same source but two other samples purified in the same way as the first by two different experimenters wcre also employed, and since little or no observable difference could be noted in the results it is believed that all three samples were of essentially the same purity. The 1-butanol was a fresh sample purified somewhat more carefully than the first; it yielded physical constants almost identical with those recorded earlier and four determinations of the solubility of naphthalene in it at several temperatures agreed very satisfactorily with the results obtained independently by Ward (10) and Sunier (8). It seems unnecessary to give these two sets of data here, especially since they are on record elsewhere (6). 6 Since the present work was completed Spiridonova (7) has reported the results of a few experiments on the system naphthalene-water-ethanol using a precipitation method (water added drop by drop), the work being carried out apparently a t 15°C. 6 Inspection of the original article of B.Iiss Christiansen and of Arrhenius' (1) discussion of it shows that all of her measurements on this latter system were confined to the temperature 25°C. The International &;tical Tables (4) thus incorrectly connect four measurements with the temperature 0°C. and four with the temperature 26°C.
SOLUBILITY OF NAPHTHALENE IN ALCOHOLS
687
Distilled water was employed in making up the rnoderatc amounts of the binary solutions used in charging the solubility tubes. The only change in the apparatus was, a t temperatures above 80°C., the use of a transparent oil as a bath liquid and minor changes in the electric heaters. The procedure was the same as that employed earlier. EXPEnlMENTAL RESULTS
In tables 1 to 4 will be found the experimental results on the four systems. The uncertainty in the temperature values is believed to be one unit (in a few eases two) in the last figure except for temperatures recorded to hundredths of a degree, where it is three units (in a few cases five). This variable precision is due to several reasons, such as the following: some of the measurements were more preliminary in nature, in other cases difficulties on the experimental side were encountered, and in still other cases it did not seem necessary to determine the particular transformation temperature with greater precision. In a few cases the temperatures appear out of line; several other determinations are, in principle, duplicate or triplicate determinations: both types are included and will serve to give an idea of the overall precision of meajurement. An asterisk (*) is employed in those cases where no (or in a few cases inconclusive) observations were made on a particular transformation temperature. A plus (+) or minus (-) sign following a temperature value means that this temperature is the lower or upper limit, respectively; the true value may be a few tenths or many degrees above or below the value given. DISCUSSION OF RESULTS
Ceneral Since considerably more work was done on the system naphthalene-waterethanol, it will be discussed first and in greater detail. It will be convenient to discuss these systems under three subheads corresponding to the transformations given in tables 1 to 4 and in the order: s 3 11,s 11 -+ 1 2 , 4 -+ 12.
+
The transformation s 3 11: the ternary ditectic surface Arrhenius (1) has shown that Miss Christiansen's data (2) on the three aliphatic alcohols may be represented within the limits of experimental error by equations of the form log N N = -K R log N A , where NN and N A stand for the mole per cent of naphthalene in the ternary mixture and the mole per cent of the particular alcohol in the binary solution, respectively. He found that the values of R a t 0" and 28°C. were so nearly equal that it appeared likely that R was independent of temperature, a t least a t these low temperatures. It seemed well, therefore, to subject the present data to Arrhenius' treatment. The data in table 2 were accordingly brought to the mole per cent basis and large plots of log NN versus 1000/Twere constructed, making use of Miss Christiansen's values a t 25" and O'C.; this procedure seemed justified, since a slight extrapolation of her 25°C. curve gave a value of the solubility of naphthalene
+
688
MANNHARDT, DE RIGHT, IIARTIN, BVRMASTER AKD WADT
TABLE 1 The solubilitg of naphthalene in aqueous solutions of methanol No,
CioHs
WEICUT OF SOLUI'ION
grams
grums
7
0.215 0.404 0.817 1.367 1.583 1.499 1.678
2.106 2.017 1.529 1.648 0.561 0.466 0.116
8 9 10 11 12 13 14 15 16 17 18 19 20
1.298 1.454 1.478 1.046 1.250 1.406 1.556 1.519 1.513 1.846 1.701 1.686 2.301
1.235 0.775 0.664 0.456 0.439 0.419 0.460 0.374 0.340 0.403 0.292 0.228 0.172
21 22 23 24 25 26 27 28 29
1 653 1.953 1.899 1.942 1.872 1.743 1.733 1.976 2.088
0.679 0.627 0.512 0.429 0.321 0.199 0.171 0.156 0.158
30 31 32 33 34 35 36
0.519 0.932 1.394 1.280 1.430 1.499 1.355
1.431 1.098 0.754 0.383 0.417 0.375 0.249 0.199 0.102
TUBE
WEIGBT OF
p
21 3 4
'
i
' 1
I
-
TUANSFORPATIOX TEXPERATURE SOLUTIOK
SOLUTIO3
. - .
-
weigh1 per cenl ,weigh6 per cent
j
1
95.45 95.45 95.45 95.45 95.45 95.45
'
93.24 93.24 93.24 93.24 93.24 93.24 93.24 93.24 93.24 93.24 93.24 93.24 93.24
51.24 65.23 69.00 69.64 74.01 77.04 77.18 80.24 81.65 82.08 85.35 88.09 93.05
90.40 90.40 90.40 90.40 90.40 90.40 90.40 90.40
70.88 75.70 78.77 81.91 85.36 89.75 91.02 92.68 92.97
89.62 89.62 89.62 89.62 89.62
26.62 45.91 64.90 76.97 77.42
N.40
1
I i
9.26 16.69 34.83 45.27 73.83 76.29
1
s
I,
"C.
35.67 50.60 63.83 66.76 70.16
71.5 71.9
* *
*
* 73.4
79.28 78.40
73.75 73 I94 66.15 70.60 72 71.95
* *
72.5 t
74.71
73 81.8 82.26 83.99 86 86.3 77.99
in pure ethanol which agreed very well with the value given by Sunier (8). Then a t rounded temperatures (30", 35", up to 70°C.) values of log N , were read o f f and plotted vemus log N b ; thoec curves which mere straight lines readily yielded
TABLE'2
The solubility of naphthalene in aqueous solutions of ethanol
cr&
-
TRANSFORKATION TEXPERATUBB
SOLUTION
IN TERNARY SOLWTION
grams
'ighl per ceai
ighl per cent
"C.
0.2140 0.3230 0.480 0.619 0.755 0.946 1.317 2.629
2.071 1.896 1.864 2.014 1.721 1.461 1.109 0.754
96.11 96.11 96.11 96.11 96.11 96.11 96.11 96.11
9.37 14.56 20.48 23.51 30.84 39.30 54.29 77.71
27.5 39.5 47.8 50.8 55.9 60.2 64.8 69.4
9 10 11 12 13 14 15
0.1977 0,2831 0.672 0.743 0.934 1.688 2.707
2.077 1.670 1.949 1.820 1.567 0.793 0.647
91.01 91.01 91.01 91.01 91.01 91.01 91.01
8.69 14.49 25.64 28.99 37.35 68.04 80.71
32.5 45.2 56.9 59.0 62.6 69.1 71.1
16 17 18 19 20 21 22 23 24 25 26 27
0.234 0.492 0.847 1.027 1,228 1.462 1.619 1.840 1.694 1.916 1.906 1.962
1.796 1.366 1.497 0.916 0.752 0.726 0.514 0.578 0.294 0.221 0.123 0.063
88.08 88.08 88.08 88.08 88.08 88.08 88 08 88.08 88.08 88.08 88.08 88.08
11.53 26.48 36.13 52.86 62.02 66.82 75.90 76.10 85.21 89.66 93.94 96.89
43.0 59.89 64.23 68 07 69.24 69.87 71.03 71.1 72.34
28 29 30 31 32 33
0.705 0.871 0.495 0.469 0.345 0.314 0.258 0.194 0.122 0.053
84.72 84.72 84.72 84.72 84.72 84.72 84.72 84.72 84.72 84.72
65.66 74.81 78.16 81.51 84.76 85.44 88.64 90.85 94.12 97.48
70.8 71.78
35 36 37
1.348 1.696 1.771 2.067 1.918 1.843 2.013 1.927 1.954 2.051
38 39
1.577 2.212
0.751 0.540
82.31 82.31
67.74 80.38
71.64
0.164 0.238 0.854 1.005
1.715 1.788 1.190 0.764
81.23 81.23 81.23 81.23
8.73 11.75 41.78 57.14
44.34 51.11 69.41 71.07
YEIGHT OF
CmHa
mIGHT OF lOLUTION
grams
1 2 3 4 5 6 7 8
TUBE NO.
34
40 41 42 43
.
TEANOL IN BINARY
689
__ s 1, __
+ 11
+I'8
".
I'
1*
-+
C '
.
73.0 74 82 76.39
75+ 77+ 77
72.1 72.4 73 72.Q 73 73.9 74.9
74.9 84.8 91 90 94+ 92+ 91+
*
97+
+ + +
76.8
-
_-
690
MANNHARDT, DE RIGHT, MARTIN, BURMASTER AND W.4DT
TABLE Z-C'ontinued TUBE NO.
ITXANOLIN BMARY SOLUTION
WEIGET OF
ClOHS
I
CloHam
s
grams
grams
eight psr cez
icight per cc,
0.790 0.791 0.798 0.722 0.643 0.467
59 60 61 62 63
1.366 1.4M 1.552 1.504 1.471 1.402 1.877 1.806 2.052 1.920 2.704 1.766 1.905 2.149 1.831 2.059 2.007 1.974 1.930 1.933
0.278 0.162 0.161 0.136 0.099 0.098 0.066 0.052 0.030 0.011
81.23 81.23 81.23 81.23 81.23 81.23 81.23 81.23 81.23 81.23 81.23 81.23 81.23 81.23 81.23 81.23 81.23 81.23 81.23 81.23
63.36 64.22 66.04 67.57 69.58 75.01 86.22 88.44 90.28 90.40 90.68 91.60 92.21 94.05 94.87 95.46 96.82 97.43 98.47 99.43
64 65 66
0.400 0.629 1.179
2.076 1.312 1.098
78.37 78.37 78 * 37
16.16 32.41 51.78
60.04 69.02
67 68 69 70 71 72 73 74 75 76
0.717 0.925 1.322 1.318 2.017 2.010 2.007 2.086 2.020 2.001 2.050 2.004
1.213 1.377 0.834 0.751 0.150 0.118 0.087
75.26 75.26 75.26 75.26 75.26 75.26 75.26 75.26 75.26 75.26 75.26 75.26
37.15 40.18 61.32 63.70 93.08 94.46 95.85 96.04 96.65 98.04 98.65 98.96
71.60
75.05 75.05 75.05 75.05 75.05 75.05 75.05 75.05 75.05 75.05
28.54
70 70.34 71.31 71.64
44 45 46 47 48 49 50 51 52 53 54
55 56 57 58
77 78 79 80
81 82 83 84 85 86
87 88
0.683 0.633 0.8% 0.756 0.930 1.032 1.145 1.302 1.267 1.677
0.300
0.236 0.221 0.204
0.086
0.070 0.040 0.028 0.021 1.710 1.544 1.583 1.281 1.422 1.433 0.683 0.766 0.717 0.880
29.08 34.37 37.11 39.54 41.87 62.64 62.96 63.86 65.58
-
T W S P O P W T I O N IEYPEPATOPZ.
lEPNAPY SOLUTION
'C.
+ 1,
In
%.
T.
71.55 71.7 72.0 72.05 73.2 73.4 73.8 73.8
75.52 77.45 81.8 94.5 118 110+ 1W+ 101+ 99.6+ 91+ 115+
71.48 71.5
*
74.2 74.40 74.92
*
75.65 76.42 76.80
e
99+ 97+ 76.7+ 77.1+
77.80 79.27
*
71.69 72.2 72.25 74.96 75.6 76.18 76.30 76.67 77.96 78.26 78.57
73.24
71.76 71.79 72.28 72.30 72.32 72.34
73.83 75.83
* *
96.8+ 87.9+
* * * *
* a
*
* *
691
SOLUBILITY OF NAPHTHALENE IN ALCOHOLS
TABLE 2-Cmludsd TUBE NO.
VEIOET 09
ClofIl
WEIOET OF SOLUIION
TEANOL m BINARY
ClpHi M
SOLUTION
--
IEBNAPY SOLIJTION
-4
.
(rams
CfMU
ighl pbr c M
righl per cm
89 90 91 92 93 94
1.413 1.189 1.442 1.473 1.994 1.968
0.737 0.618 0.713 0.701 0.060 0.047
76.06 76.06 76.05 75.06 76.06 76.05
66 72 66.80 66.91 67.76 97.08 97.66
96 96 97 98 99 100 101 102 103 104 105 106 107 108
0.1726
2.428 1.796 1.971
6.64 12.79 17.08 24.66 28.22 27.92 30.29 30.42 31.47 31.62 35.40 94.29 99.14 99.61
49.2 63.3 66.8 70.8 71.4 71.8
0.009
71.81 71.81 71.81 71.81 71.81 71.81 71.81 71.81 71.81 71.81 71.81 71.81 71.81 71.81
109 110 111 112 113 114 115 116 117 118 119
0.600 0.589
1.689 1.493 1.285 1.410 1.428 1.298 1.326 1.636 1.428 1.328 1.332 1.191
71.79 71.79 71.79 71.79 71.79 71 * 79 71.79 71.79 71.79 71.79 71.79 71.79
27.41 28.33 29.20 29.25 29.38 30.33 30.67 31.61 31.87 34.74 36.64 36.58
71.79 71.93
im
0.2634
0.408 0.616 0.667 0.668 0.720 0.699 0.667 0.662 0.844 2.148 2.189 2.319
0.530
0.683 0.694 0.566 0.686
0.710 0.668 0.707 0.767 0.687
l.W 1.877 1.725 1.667 1.699 1.431 1.410 1.640 0.130 0.019
- -
P M N ~ O W I I O NIEKPEPAIUPE 8
QC
+ I,
1.
'C.
72.33 72.31 72.30 72.4 77.1 77.40
I
72 72 72 72
* *
79.1
I1
I*
"C.
* * * * *
*
74.1 74.6 76.2 77.0 81.8 82.6+ 81.8+
79.6
72.02 72.01 71.98 72.00 72.00 72.00
*
72.07 72.06 72.06
73.6 73.5 73.5 74.66 75.00 77.7 80.31 80.95 84.3 83.92
K and R. From 30" to 55'C. the values of R were quite constant, the average being 2.710, and the values of R obtained from a study of the data of Mise Chiistiansen at 0' and 25°C. agree well with it. At temperatures above 55OC. it waa difficult to paas a straight line through the points, owing t o curvature, perhaps explicable by the proximity to the solubility gap; hence these points are omitted. The values of K and R will be found in table 5. It is necessary to retain all of the figures in both K and R in order to attain the probable accuracy of the values of the solubility of naphthalene in pure ethanol; aa the value of Ns becomes smaller, it is probable that there is considerable uncertainty in the last figure of both K and R. From Miss Christiansen's data at 25C. Arrhenius gives the slope 2.8, a value
692
‘\I.iXSH.ARDT,
DE RIGHT, II.iRTIS, BURZLISTER A S D W.IDT
which accord;: ,satisfactorily vtth the value 2.710 given in table 5. At 0°C. he gives tlie value 3.0, but there are only four experimental points a n d t ~ ofo these are very iiearl>. purc ethanol; since the points deviate considcrabl!- from the best TABLE 3 The solubility of naphthalene in aqueous solutions of 1-propanol ,\EIGHT O F
IUUE N O
SOLUTION
soLuIIox
C:oHa IN IERNARY SOLETIOS
- P R O P F O L I: IIS1RY
__1 2 3 4 6
Qm,nr
grams
.eight par cen
xeigb! 9er can
’C.
0.284 0.421 0.452
1.814
89.95 89.95 89.95
13,5i 17.36 24.59 32.15 38. 53 54.31
40 91
2.004
6
0.652 0.531 1.110
7 8
1.296 1.366
1.478 1.376 1.326 0.934 0.776 0.366
0.70s
1.417
84.??
0.693 0.795
1.m
si. 22
9 10 11 12 13 14 15 16 17 18
0.918 1.188 1.0Y3 1 20s
1 108 1.511
19
0.2‘47
20
0.u3 0.577 0.782
21 22 23
25 26 27 28 29
0.912 0.934 1.010 1.009 1.005 1.001 1 001
30
1.000
31 32 33 34
1.100
24
1.093
1.207
1.396 1.587
~
,
8 1 22
0.544
84.22
1.593 1.556
80 06 80.06
1.501
80.06 S0.06
1.235 1.117 1.047 1.023 1.003
80.06 80.06
0.9%
80.06
so.06
0.906 0. Si8
bn 06
0.320
~
80 06 80 06 SO 06
_
’
69 50
_
52 49 53 25 55 2s 57 15 60 87 83 22
~
70 11 ’70.62
86t 86$
68 78
70 5+
68 91 69 2 69.07 70 25 72 0
69 5+ 80.3+ 81+ 811 81+
52.13 58.19 61.92 66.05 67.30 67.95 68.47 68.20
19.68 60.15 51.28 51.07
so 06
0.602
62.02 62 05 63.73 64 89 65 93 68 21 68 62
47.15
SO 06
0.800 0.905
32
15.71 21.83 27.77 38.77 41.95
s0.m b0.06
0.925
65.82 67.53 70.77
10
75 51 65 55 05 55 70 133 5s 69 70 78.53
84.22 84 22 8 1 22 84 22 84 22
0.070 0.769 0 692 0 612
55.5 61.24
70.11 33 33 37 41 15
‘C.
16.67 53 6
62.56
S4.?2
1.311 1.216
n.m
59,95 s9.95 59.95 s9.55 s9.95
“C.
68.65
68.74
1
’
, 1
_
_
~
1
-
’
straight line there is coniiderable uncertainty in the slope. From the prcqent work it 11-ould appear better to call the slopr 2.710, and a curl-e so d i a m fits the upper thrcc points quite nell.
693
SOLUBILITY OF NAPHTRALENE IN ALCOHOLS
TABLE 4 The solubility of naphthalene in aqueous solutions of 1-butanol TUBE NO.
WEIGHT OF
CioHs
WEIGHT OF SOLUTION
I
~-BDTANOL IN BINARY SOLUTION
per CLI
CldIa I N
TBANSFOBMATION TEhCPERATUBE
TERNARY
&hi per
"C. 21.76 29.59 39.57 49.0 52.7 54.99 59.44 62.90 65.43 69.23 71.8 73.55 76.13
grams
giams
0.163 0.223 0.310 0.497 0.609 0.685 0.814 1.045 1.253 1.504 1.656 1.761 1.889
1.809 1.796 1.586 1.530 1.504 1.441 1.149 1.012 0.864 0.521 0.311 0.207 0.099
94.71 94.71 94.71 94.71 94.71 94.71 94.71 94.71 94.71 94.71 94.71 94.71 94.71
8.27 11.05 16.35 24.52 28.82 32.22 41.67 50.80 59.19 74.27 84.19 89.48 95.02
1.650 1.MO 1.643 1.405 1.305 0.967 0.886 0.501 0.260 0.136 0.119 0.044
89.71 89.71 89.71 89.71 89.71 89.71 89.71 89.71 89.71 89.71 89.71 89.71
9.98 16.58 21.24 30.99 39.22 51.24 59.41 75.00 86.99 93.20 94.16 97.81
30.73 43.50 51.7 56.74 60.86 64.93 67.00
25
0.183 '0,326 0.443 0.631 0.842 1.016 1.297 1.503 1.738 1.864 1.918 1.961
26 27 28 29 30 31 32 33 34 35
0.266 0.367 0.537 0.775 0.927 1.166 1.586 1.798 1.915 1.970
1.733 1.649 1.487 1.352 1.087 0.855 0.427 0.184 0.141 0.053
85.04 85.04 85.04 85.04 85.04 85.04 85.04 85.04 85.04 85.04
13.31 18.20 26.53 36.44 46.03 57.69 78.79 90.72 93.14 97.48
41.79 48.8 56.43
36 37 38 39 40 41 42 43 44 45
0.336 0.475 0.664 0.816 0.986 1.217 1.515 1.800 1.865 1.979
1.794 1.589 1.378 1.075 0.940 0.862 0.429 0.188 0.084 0.061
81.31 81.31 81.31 81.31 81.31 81.31 81.31 81.31 81.31 81.31
15.77 23.01 32.52 43.15 54.19 58.54 77.93 90.54 95.69 97.01
1 2 3 4 5 6
7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
24
rcigkt
I
"C.
70.14 73.05 75.18
*
*
61.72 64.48 67.15 71.23 74.51 75.42 77.69 47.28 54.69 60.33 64.05 66.02 67.60 71.11 74.44 76.71 77.47
'C
.
loo+
loof
100-
100100-
* 64.6+ 93+
*
76f
* *
64.8 75 f 98+
*
go+ 150f 115f 85
+* *
694
MANNHARDT, DE RIQHT, MARTIN, BURMASTER AND WADT
If the equation proposed by Arrhenius is fundamentally correct, the values of K should yield the solubility of naphthalene in pure water a t the various temperatures. The values so obtained appear too small' and it is evident that the different alcohols yield different K values, whereas K should be independent of the alcohol employed. It therefore appears either that this particular form of equation is not valid over the whole range of concentration or that the present data are not sufficiently precise to make it possible to evaluate K and R satisfactorily. It is almost certain that the slopes will not be found constant at all temperatures and concentrations, because this would require that the log N K versus 1000/T curves for two different solutions should be equidistant a t all temperatures and, a t constant temperature, equal differential heats of solution regardless of the concentration. In spite of these shortcomings of the equation proposed by Arrhenius, it appears to be very useful for purposes of calculation, a t least for the range of concentration employed in this research. With 1-butanol there appeared to be some curvature in the log N N versus log Ns lines a t lower temperatures. This may be due to the expected solubility gap at rather low concentrations of naphthalene and high concentrations of water. The values of K lead to values of the solubility of naphthalene in pure water somewhat larger than the expected order of magnitude. The data on 1-propanol are not sufficiently numerous to evaluate K and R to better than one hundredth of a unit; the values of the solubility of naphthalene in pure 1-propanol calculated from these constants will thus hardly equal in accuracy the rounded values published earlier. Arrhenius gives 2 as the value of the slope a t 25°C.; this accords well with the present value, and Miss Christiansen's curve gives a solubility of naphthalene in pure 1-propanol which agrees very satisfactorily with that published earlier. The values of K lead to values of the solubility of naphthalene in pure water of the expected order of magnitude. In the case of methanol the measurements are again rather few in number and, as mentioned in an earlier paper, there is some question as to the purity of the methanol. The values of R cannot be considered more than limiting slopes. Arrhenius gives 4.1 for R at 25'C.; this agrees well with the value given in table 5, which was obtained after carefully studying Miss Christiansen's work along with the present work at higher temperatures. At 0°C. he gives the value 4.8, which appears definitelv out of line with the trend of the R values in table 5, but his value is based on only three points, so that the case is much the same as discussed under ethanol. I t will be noted that with methanol alone does the value of R change with temperature to such a degree as could hardly be attributed to experimental error. The values of K are seen to be very negative; it would appear, therefore, that the log N X versu8 log N , curves would show definite curvature at lower values of N N and N a . Attention has been called, in the earlier paper, to the fact that Ward's results on the solubility of naphthalene in methanol are about 8 per cent higher than those reported for the sample of methanol used in this research. A very slight
'
The only values of the solubility of naphthalene in pure water which have been found ' and 25"C.,respectively. (3) lead t o K values of -3.57 and ~ 3 . 3 8a t 0
695
SOLUBILITY OF NAPHTHALENE IN ALCOHOLS
extrapolation of Miss Christiansen's curve a t 25°C. yields a value identical with Ward's. In view of these facts it seemed right to consider whether these two sets of results could be brought into agreement on the assumption that the methanol used in these researches contained a certain amount of water. The temperature 50.6"C. was chosen for this study because both Sunier and DeRight had independently made up and run tubes containing dperent amounts of water; calculations of N Nand N Mfor these tubes and for the "pure" methanol were then made, assuming the percentages of water to be 0.2, 0.6, and 1.0; then the logarithms of these three values and Ward's value were plotted. With 0.6 per cent water the four points fell quite well on a straight line of slope almost the same as that of the three points on the original basis; with 0.2 per cent water the curve showed a curvature in a direction not noted in any other case; while for 1.0 per cent water all four points fell on a smooth curve with moderate curvature in a direction observed in several other cases. This tends to prove that the methanol TABLE 6 Constants for equations for the ternary ditectic surface
1 I I 1 1 1 1 1
PANCK OB
V A L U E S O B C O N S T M S AT
O'C.
_____--___ Yethnol
.....{ :;;,::'
ZS'C.
4.27 - ~ 8 8 -4.808
.{ E;;,',;; -8.101.64 1-Butanol.....{ I.,',; l-propancl...
3S'C.
WC.
50'C.
4S'C.
SS'C.
WC.
*z;:fl
__ -----___
-8.19
K .....
30°C.
CONCENTRAIION. MOLE PEP CENT
-8.28 4.36
-8.38 4.44
-8.46 4.64
-8.66. 4.88
-8.66 4.74
-8.18
4.86
SOLUTION
-8.88 4.98
90-100
-4.730 - 4 . ~ 9 - 4 . ~ 6 ~-4.462 -4.340
-4.221
SO-1W
-2.a 1.80
4.48 1.00
IC-100
-1.718 -1.878 -1.572 1.421 i.tai/ M I
-1.4.50
-3.01 1.w
-2.92
-1.058
-1.814
,
1.421
1.00
i.4a1
-2.88 1.80
4.73 1.80
i
1.421
-1.302 1.421
80-100
contained about 0.6 per cent water, but it is not positive proof, since Ward's methanol may have contained some water or some component which tended t o increase the solubility of naphthalene. It is apparently necessary to leave this question still open; if in the future it should be proven that a small percentage (such as 0.6 per cent) of water was present in the methanol, the only changes necessary in table 1 will be in the values in column 4;m regards table 5, it is almost certain that the limiting slopes will be found satisfactory and the values of K will be made more positive by 0.02 to 0.03 units depending on the temperature.
The transformatian 8
+ 11 --+
12: the three-phase monotectic equilibrium curve and quantities derivable from it
Sectional graphs (5) of weight per cent versus temperature were constructed from the data in columns 5 to 8 of table 2. In figure 1 will be found curves for three solutions, experimental points being omitted since the scale is so small.
696
hlANNHARDT, DE RIGHT, MARTIN, BLXXIASTER AND WADT
85 80
,o
h
75
%To
B
BF 65 60
0
40
20
60
80
Ku
h/e/yhhfper cenf nuphfh/eoe in M e hrnury sy.dem FIG.1. Sectional graphs for three solutions in the system naphthalene-water-ethsnol TABLE 6 Data on the three-phase monotectic equilibria existing in the four systems
i ALCOHOL I N
POSITION ON SECTIONAL GRAPH
Lower intersection of lour
Upper intersection of four
phase areas
phase areas
ALCOHOL
CioHa in %nary solutk wight per cen
Methanol
‘
Ethanol
1-Butanol.., . . . . . . . , . .
. /I
90.40 71.80 75.05 75.26 78.37
1
28.8 38.2 38.3 53
71.5 72.00 71.74 71.72 (71.47)
Temperature
T.
95.5 92.1 99.4
75.1 73.6 79.4
99.0
78.6
98.0
77.6
97.2 97.0
76.7 76.5
81.31 85.04 78
The intersections of fours phase areas (for example, the points a,b, c, d, and e in figure 1) galre the points listed under ethanol in table 6. 8 The upper boundary of the “fourth” phase area is given by the line akb (for one sectional graph); the lower boundary does riot fall within the scope of the present paper. The reader may gain an idea of the probable shape of the lower boundary by studying
697
SOLUBILITY OF NAPHTHALENE I N ALCOHOLS
The first three of the lower intersections gave little if any difficulty on the experimental side; the fourth is based on rather meager data,-two s -+ 11 determinations carried out with care and a third tube, not run carefully in the solubility apparatus, which became very milky in appearance on supercooling. The observation of this phenomenon, which almost invariably occurred when the percentage of naphthalene was slightly less than that corresponding to the point, served to fix the lower limit of concentration for this point, the temperature being obtained from a curve to be discussed later and therefore put in parentheses. The fifth (point a, figure 1) gave some difficulty on the experimental side, owing to the opalesccnce which appeared and persisted for considerable periods of time; with tube number 44 this was especially true and with the next tube to a lesser extent. At one time a bluish color was seen in tube 45. There may be an uncertainty of 0.05’ in the temperature given for this intersection and considerable uncertainty in the composition because of the supposed proximity to the plait point. The sixth point is based on rather meager data,-the supercooling phenomenon mentioned above but observed carefully by two independent workers who found that the cloudiness appeared a t 70.4’C. (the temperature, 71.64’C., given in table 2 for the transformation s -+ 11 is believed to be about 0.05’C. high). The seventh point offered no difficulty but the eighth did to some extent, owing to opalescence and the formation of bubbles during the run. At the upper intersections of four phase areas there was in almost every case some difficulty in determining conclusively the character of the transformation or the exact temperature of transformation; as the amount of second liquid phase became smaller it could be noted merely by the phenomenon of non-wetting of the walls of the tube. A simple calculation employing the lever principle on the suitable tie lines showed that in certain cases the ratio of weights of the two liquid phases approached 400 to 1 and with a total weight of 2 g. the lesser phase would weigh only 5 mg. and thus might escape notice. The curves showing the course of the l1 -+ la transformation were so nearly vertical in this region as to assist materially in fixing the intersections more precisely, thus compensating to a considerable degree for the difficulty just mentioned. These intersections when plotted on triangular coordinate paper fall very near to or directly on a smooth curve (curve E, figure 2). The points a, b, c, and d in this figure are the points so designated in figure 1. A slight extension of the curve to the W-N plane yields a value of the solubility of water in naphthalene around 0.1 per cent, the temperature being very near 80’C. (this would be a quadruple point for this binary system). Sunier, in an unpublished research, found that a tubk containing naphthalene and 2.3 per cent water showed an s ll -+ ll transformation a t about 79.9’C., and up to 82.5”C. there seemed to be no change in the size of the two small droplets of water-rich phase; this observation is in qualitative agreement with the above values. Data (4) on the mutual
+
Marsh’s discussion ( 5 ) of type XIII. A number of observations not recorded in this paper are believed to be in accord with that discussion. The notation 8 11 + 1%is used in this paper to denote the phases in equilibrium at the upper boundary of the “fourth” phase area and on the three-phase monotectic equilibrium curve.
+
698
MANNHARDT, DE RIGHT, MARTIN, BURMASTER AND WADT
solubility of benzene and water and of toluene and water also seem in line with the above values. The quantities derivable from the three-phase monotectic equilibrium curve are the tie lines making up the ruled surface and the plait point which may be considered the "last" tie line. From the various experimental points on the curve, perpendiculars were dropped to the W-N plane; these values when plotted versus the temperatures given in table 6 yielded a smooth curve which passes through a minimum. On this curve a t the first three temperatures gken in
lkne
FIQ.2. Projection on N-W-A plane of (a) three-phase monotectic equilibrium curves (M, E, P, and B) for all four systems, ( b ) tie line (dt) on ruled surface at 72.OO0C., and (c) 85°C. isothermal (mn) on ternary dichortic surface for the system naphthalene-waterethanol. TABLE 7 Compositions of conjugate solutions in equilibrium with solid naphthalene in the system na.ohthalene-water-ethano2 TEMPERATURE
C*&
oc. 72.00 71.75 71.50 71.45
weight Bcr ccnf
28.8 37.2 60.0 57.5
ClHrOH
Hs0
weigh1 per ccnl weithi &I cent
51.2 46.8 38.9 33.8
20.0 16.0 11.1 8.7
CioHa weight pcr cent
78.2 73.1 64.2 57.5
CnHaOH
H10
weight )cr cent weight per ccnt
18.5 22.4 29.2 33.8
3.3 4.5 6.6 8.7
table 7 there were two values for each temperature; these were accordingly read off, and a t these values on the triangular plot Perpendiculars were erected and extended to the curve. These two points a t each temperature therefore gave the compositions of the conjugate solutions in equilibrium with solid naphthalene; they are given in table 7 and a typical example is. found in figure 2, points d and t , which applies a t the temperature 72.OOOC. The plait point is, simply enough, the lowest point on the plot but must be treated in the same way; the result so obtained is plotted in figure 2.
SOLUBILITY OF NAPHTHALENE IN ALCOHOLS
699
The positions of the tie lines were also determined by reading off from the working sectional graphs the intersections of the horizontal temperature lines with the respective slightly curved lines representing the s 11 -+ 12 transformation; by way of illustration, in figure 1 if the compositions corresponding to the points d, h, and k are read off and then plotted on the respective section lines indicated a t the left of figure 2, they fall on or nearly on the line dt. The results obtained by this second method agreed satisfactorily with those listed in table 7 but are not given, because they are believed to be somewhat infeiior in precision owing to the scarcity of experimental points on certain sectional graphs. The plait point was also determined by extending the curve connecting the midpoints of the tie lines, and the result agreed satisfactorily with that given in table 7. With methanol the observations are not sufficiently numerous to enable one to say definitely that the plait point has been reached, but it appears to be in the vicinity of 71.5"C.and a composition around 65 per cent of naphthalene. Tube No. 32 appeared opalescent over a several degree range of temperature; hence the values given in table 6 for this lower intersection of four phase areas are only approximate. The other three intersections appear much more satisfactory. The uncertainty as to the purity of the methanol produces a little uncertainty in the position of the section lines; if, say, 0.6 per cent of water was present in the methanol this would shift curve M (figure 2) very slightly upward, to a lesser extent as the percentage of naphthalene is increased. With the remaining two alcohols it is evident that the plait point has not been reached, and i t is accordingly possible to determine the positions of the tie lines only qualitatively. With methanol the plot of projected values versus temperature resembles that for ethanol, but with 1-propanol the curve is quite a little lower and with 1-butanol it is lower still and of a different shape. On examining figure 2 it appears impossible to correlate the four curves by any rational means; however, if the compositions are all brought to the mole per cent basis, correlation is quite easy. There is a very regular and relatively large change as one passes from methanol to ethanol and thence to 1-propanol, but the curve for 1-butanol falls near that for ethanol, between ethanol and methanol, and thus a t first sight it appears out of line. However, when the temperature is considered it is very evident that raising it to around 7OoC.would shift the curve in the right direction and undoubtedly to a position one would normally expect. I t is quite evident that the character of the contiguous binary system l-butanolwater, displaying as it does two liquid phmes over a considerable range of concentration and temperature, greatly affects the shape of the three-phase monotectic equilibrium curve.
+
The transformation 11 -+ 12: the ternary dichrtic surjace Reference has already been made to experimental difficulties encountered in the system naphthalene-water4hanol when the composition of the system was near that of the upper intersection of four phase areas. As the concentration of naphthalene was decreased by small amounts, the liquid phase present in the
700
MAIWHARDT, DE RIGHT, MARTIN, BURMASTER AND WADT
smaller amount generally gave the appearance of very fine bubbles which reflected light very well. On stopping the eccentric these bubbles graduallyrose t o the surface and formed a very thin layer; thus they were of lower specific gravity than the main body of the liquid. Generally speaking, it J$as very difficult to tell a t what temperature the system became homogeneous, no perfectly satisfactory criterion of homogeneity having as yet been discovered. By way of illustration it may be said that in tubes having numbers between 51 and 56, bubbles could be produced, by rather vigorous shaking of the rocker arm, over a range of several degrees. With tube S o . 56 the bubbles were not stable above 107°C. but up to 115°C. the walls of the tube were not wet well by the liquid; this temperature is accordingly set as the lower limit of homogeneity. With the binary solutions having compositions greater than 80 per cent ethanol and thus giving lower intersections of four phase areas to the right of the plait point, thc presence of bubbles was noted on both branches of the 1, -+ l2 curve, but as one approached the lower intersection of four phase areas the bubbles \
