THE SOLUBILITY OF ACETYL-O-TOLUIDINE IN VARIOUS SOLVENTS J. L. HALL,e A. R. COLLETT, AND c. L. LAZZELL Department of Chemistry, West Virginia University, Morgantown, West Virginia Received July 8, 1983 INTRODUCTION
In previous communications to This Journal, Collett and Lazzell have reported a series of measurements of solubility for several systems of disubstituted benzene derivatives, namely the nitroanilines (l),the aminobenzoic acids (2), the nitrobenzoic acids (3), and the dihydroxybenzenes
(4). A survey of the literature revealed that no systematic investigation of the solubility of the acetyltoluidines in a series of solvents had ever been reported. The present investigation was undertaken with the primary object of obtaining data for another system of disubstituted benzene derivatives which could be used in the study of the solubility relations of systems of this type. These measurements are of value in themselves, since the acetyltoluidines are of some commercial importance. In this paper are presented solubility measurements for acetyl-o-toluidine in methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, acetone, chloroform, carbon tetrachloride, benzene, diethyl ether, and water from about 25°C. t o 110.3"C., the melting point of the solute. The heat of fusion of acetyl-o-toluidine has been calculated. MATERIALS
A. Acetyl-o-toluidine The acetyl-o-toluidine used in these determinations was the best grade obtainable from the Eastman Kodak Company. As received, it had a melting point of 107.1"C. After one crystallization from water it melted at 110.3"C. A little tar was observed to be formed around the beaker. A second crystallization from water gave no tar and no further change in 1 Contribution No. 92 from the Department of Chemistry, Division of Industrial Sciences of West Virginia University. From a part of the thesis presented t o t h e Graduate School of West Virginia University, in June 1932, by James Lester Hal1 in candidacy for the degree of Master of Science. 1087
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J. L.,HALL, A. R. COLLETT A N D C. L. LAZZELL
melting point. Recrystallization of this product from alcohol gave no further change in melting point'. For this reason it was concluded that the material which had been crystallized from water once and thoroughly dried was of sufficient purity for use. The melting point given in the International Critical Tables is 110.3"C. Before using, the material was dried over calcium chloride and then over concentrated sulfuric acid.
3. Solvents All the solvents used in this investigation, except water, were carefully dried and distilled several times until a product having a satisfactory TABLE 1 Physical properties of solvents
BOILINO RANGE
SOLVENT
BOILING POINT (INTERNATIONAL CRITICAL TABLES)
___
~~
Methyl alcohol. . . . . . Ethyl alcohol.. . . . . . . . . . . . . . . . . . . . . . . . . n-Propyl alcohol. . . . . . . . . . . . . . . . . . . . . . . Isopropyl alcohol. . . . . . . . . . . . n-Butyl alcohol.. . . . . . . . . . . . . . . . . . . . . . . Isobutyl alcohol. . Benzene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
degrees C.
64.3 78.4 97.1 82.0-82.2 117.9 106.9-107.0 79.98-80.02' . . . . . . . . . . . . 55.8-56.0 e. . . . . . . . . . . . . . . . . . . 76.5 Chloroform, . . . . . . . . . . . . . . . . . . . . . . . . . . . 60,8-61,1 34.25-34.35 Diethyl ether.. . . . . . . . . . . . . . . . .
degrees
REFRACTIVE I N D E X
Found
International
t
Critical Tables
1.3291 1.3618 1.3854 1.3790 1.3992 1.3958 1.5012 1.3599 1.4603 1.4461 1,3528
1.329 1.361 1.386 1.378 1,3993 1.396 1.5014 1.3591 1.4607 1.4467 1.3526
____
C.
64.5 78;5 97.8 82.3 117.7 107.3 79.6 56.1 76.8 61.2 34.5
* Richards and Barry (J. Am. Chem. SOC.37, 996 (1915)) give 80.2"C. as the boiling point of benzene. boiling range was obtained. Freshly redistilled water was used. In table 1are listed the boiling ranges and the refractive indices of the solvents used. All temperatures were obtained by use of thermometers certified by the Bureau of Standards and corrections were made in each case for stem emergence. The boiling ranges were all reduced to 760 mm. pressure. METHOD
The experimental data on solubility presented in this article were obtained by the synthetic method. Details of the procedure used here are fully explained in a previous paper (5). All of the determinations were checked by at least two trials and many were repeated by duplicate bulbs.
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SOLUBILITY OF ACETYL-0-TOLUIDINE
TABLE 2 Experimental values of the solubility of acetyl-o-toluidine i n terms of mole percentage
//
Methyl alcohol degrees
100.00 86.00 83.60 74.35 69.50 63.60 59.80 55.48 45.55 36.45 26.50 22.34 10.31
110.3 102.4 100.7 94.9 91 .o 86.5 83.3 79.6 71 .O 61.4 47.9 42.1 18.3
Isopropyl alcohol
//
Ethyl alcohol
c.
n-Propyl alcohol degrees C .
degrees C .
I
1
11
100.00 85.50 79.95 71.90 64.60 54.94 47.55 41.37 31.80 24.45 13.99 9.20
110.3 102.0 99.2 93.5 87.7 80.8 75.2 69.9 60.3 52.3 34.8 23.9
100.00 86.80 63.30 53.20 49.38 40.40 32.30 20.15 15.18
//
n-Butyl alcohol
110.3 103.2 87.4 79.2 76.2 68.9 60.0 45.0 36.7
Isobutyl alcohol
100.00 92.80 82.20 72.50 61.10 51.70 41.30 33.94 25.61 23.13 21.72 11.31
110.3 106.2 100.2 94.4 86.7 79.8 71.8 66.0 57.1 54.1 52.2 34.5
100.00 88.20 67.80 63.10 50.35 42.14 33.40 21.58 10.50
110.3 103.5 90.6 86.7 77.2 70.8. 62.1 47.7 26.5
100.00 87.60 78.80 67.92 57.90 50.06 42,35 30.51 20.74 10.30
110.3 103.1 98.0 91.4 83.0 77.2 72.3 60.7 49.2 30.1
100.00 87.82 80,30 69.48 60.30 44.54 35,97 27.68 18.26 9.78 7.22 3.00
110.3 103.6 98.6 92.6 87.2 76.8 71.5 65.8 59.3 52.3 49.6 40.8
100.00 91.60 82.52 71.30 68,50 52.82 38.37 29.01 19.16 11.43
110.3 105.5 100.3 93.4 91.6 79.9 68.1 58.7 46.0 31.2
100.00 91.24 77.75 66.73 59.63 49.44 38.06 29.92 20.57 11.35 6.21 2.313 .718
110.3 105.7 98.1 91.9 88.0 81.8 75.4 71.0 66.2 61.1 57.7 52.2 41.1
’
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J. L. HALL, A. R. COLLETT AND C. L. LAZZELL
.*_
c
l
t
Chloroform
c
110.3 104.1 98.0 96.0 83.2 74.1 64.8 50.7 38.2 22.1
.
t
C
Diethyl ether
degrees C.
100.00 89.30 79.80 76.90 61.70 52.90 45.42 35.65 28.11 21.00
I
I
110.3 106.2 99.9 95.2 90.4 84.6 80.0 76.0 70.8 63.4 48.7 27.7
100.00 90.00 80.00 70.00 60.00 50.00 40.00 30.00 20.00 10.00
110.3 105.0 99.2 92.9 85.8 77.9 68.4 57.2 42.4 20.1
I
__
Water
degrees C.
100.00 91.90 79.70 70.03 60.55 47.72 35.90 24.96 12.85 5 900 2.288 1.146
t
loo. 00
I
degrees C.
110.3 Forms a triple point at 79.6”C. over an undetermined range
0.380 0.1743
69.0 43.3
EXPERIMENTAL RESULTS
The experimental measurements of the solubility of acetyl-o-toluidine are listed in table 2, C being the molal percentage of the solute (C = 100 N , where N is the mole fraction of the solute) and t the temperature in degrees Centigrade. The thermometers used were checked against thermometers calibrated by the Bureau of Standards. All readings were corrected for emergent stems. The results marked “ideal” were calculated as will be explained in the next part of this paper. The results presented in table 2 were plotted on a large scale in terms of C versus t, and from these curves values of solubility have been obtained at 5-degree intervals of temperature. Table 3 was constructed from these values.
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SOLTIBILITT O F ACETY L-0-TOLUIDINE
TABLE 3 Solubilitv of acetyl-o-loluidine in various soluents, inlerpolated at a series peratures, expressed in terms of mole percentage nTEMPER. ATURE
METHYL ETHYL LLCOHOL ALCOHOL
-25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110.3
n-
ROPYL ALCOHOL
180-
BUTYL PROPYL ALCOALCOHOL HOL
180BUTTL
AL&O-
BENSENE
DI-
CHLOROFORM
ACETONE
22.1 24.2 26.5 29.1 32.1 35.2 38.5 42.0 45.5 49.5 53.7 58.5 63.5 69.4 75.7 82.9 90.9 100.0
8.7 10.8 13 2 15 5 18.4 31.9 25.7 30.2 35.1 40.5 46.6 53.0 59.7 66.4 73.8 81 8 90 5 100.0
;;;;-
TETRA-
HOL
01 temETR~L ETHER
-__--___--L_-
-
15.6 9.5 17.7 11.6 12.0 19.8 14.0 14.4 22.2 16.4 17.0 24.7 19.3 20.0 27.9 22.7 23.5 31.4 26.8 27.6 35.4 31.5 32.3 39.7 36.3 37.0 44.6 41.5 42.3 50.2 47.4 47.9 56.0 53.9 54.3 61.9 60.5 61.0 68.2 67.0 67.2 74.7 74.1 74.1 82.1 81.8 81.6 90.6 90.0 90.5 100.0 100.0 100.0
10.0 12.0 14.4 17.0 20.0 23.3 27.2 31.5 36.0 41.2 47.4 54.0 60.7 67.0 74.7 82.1 90.6 100.0
9.3 11.6 14.0 16.8 20.1 23.9 28.5 33.5 39.2 45.5 52.0 58.6 65.8 73.5 81.7 90.3 100.0
8.2 10.2 12.7 15.0 17.8 21.2 25.2 29.7 34.4 39.8 46.0 52.3 59.0 65.9 73.6 81.8 90.4 100.0
-
-
-
0.8 2.2 4.3 7.5 12.6 19.2 26.8 34.0 41.5 49.4 56.9 65.0 73.3 81.8 90.3 100.0
0.6 0.7 0.8 1.5 3.7 9.5 13.4 28.0 37.3 46.0 54.5 63.2 72.0 81.0 89.8 100.0
0.9 1.3 1.5 1.8 2.0 2.4 3.1 4.5 6.9 11.7 22.0 36.0 47.7 59.7 69.8 79.9 89.6 100.0
DISCUSSlON OF RESULTS
As far as could be determined, the heat of fusion of acetyl-0-toluidine has not been reported. It will be noted by inspection of the solubility curves (figure 1) that they all approach the melting point of the solute a t approximately the same slope. Since a solution of the type studied here will be nearest t o the ideal a t high concentrations of the solute, it is reasonable to suppose that this slope is approximately the slope of the ideal solution curve. The molal heat of fusion was obtained from the slope of curves secured by plotting log N versus 1/T and by substitution in the usual ideal solubility equation,
where log N is the logarithm to the base 10 of the mole fraction of the solute,, T, is the melting point of the solute, T is the solution temperature of a particular system containing an amount of solute t o give a mole fraction N , and L, is the molal heat of fusion. In this way a large number of values were obtained ranging between 5500 and 5900 calories. The average of all values gives 5700 calories for the molal heat of fusion of acetyl-o-toluidine.
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J. L. HALL, A. R. COLLETT AND C. L. LAZZELL
Using this value for the molal heat of fusion, the ideal solubility curve for acetyl-0-toluidine was calculated by solving for T for each 10 mole per cent from 10 to 100. Figure 1 is a plot of part of t'he data of table 2. Since the curves for the alcohols are grouped so dose together, only three are shown. The ideal curve is also shown. Figure 2 shows the curves for the alcohols on an enlarged scale over part of their range.
FIG. 1. SOLUBILITY CURVESFOR ACETYL-0-TOLUIDINE IN VARIOUSSOLVENTS
Except for methyl alcohol, the solubility curves for the alcohols and acetyl-o-toluidine form a very narrow band, This band is approximately coincident with the ideal curve above 60 mole per cent and shows increasing divergence below this point,. Arrangement of the alcohols in descending order as to solvent power gives: methyl, propyl, ethyl, isobutyl, isopropyl. It is interesting to note that, of the alcohols studied, except methyl, propyl has the greatest solvent power, and isopropyl the least, while butyl had next to the greatest solvent power, and isobutyl next to the least. Evidently branching the carbon chain of the alcohol has a greater effect on
SOLUBILITY OF ACETYL-0-TOLUIDINE
1093
the amount of acetyl-0-toluidine which it will dissolve than does the addition of an atom of carbon t o the end of the chain. There is no evident relationship between the melting points of the alcohols and the rate at which the curves break or their relative positions on the sheet. The curve for acetyl-0-toluidine and acetone is in the narrow band formed by the alcohol curves, being midway between the ethyl and isobutyl curves. This curve is very near t o the ideal curve above 50 mole per cent. The dielectric constant of acetone is about of the same order as that of the alcohols and this may indicate that there is some relationship between t,he polarity and the solubility.
FIG.2. SOLUBILITY CURVES FOR ACETYL-0-TOLUIDINE IN SEVERA ALCOHOLS L
The acetyl-o-toluidine was much more soluble in chloroform than in any other solvent studied. It is soluble to the extent of 23 mole per cent at 25°C. The curve is of the same general shape as the alcohol curves, but a t low concentrations of solute it shows greater divergence from the ideal curve and the divergence is in the opposite direction. Its dielectric constant is not of the same order as that of the alcohols, being much lower. The curve for carbon tetrachloride is rather unusual. It is almost exactly a straight line from 10 to 100 mole per cent of the solute. It is in this respect very different from the alcohols, acetone, and chloroform. Acetyl-0-toluidine was less soluble in ether than in any other solvent studied except water. This curve, while nearly straight, shows slight
1094
J. L. HALL, A. R. COLLETT AND C. L. LAZZELL
reverse curvature at about 30 mole per cent. It breaks rather gradually below 15 mole per cent and crosses the carbon tetrachloride curve a t 3 mole per cent and the benzene curve at about 1.5mole per cent. Acetyl-o-toluidine in water gives the phenomena of two liquid phases over a very wide range. It forms two liquid layers a t about one-half mole per cent ,of solute and up to a concentration which has thus far not been determined exactly. No attempt was made to determine the critical solution temperature. The temperature of this triple point is near 79.6"C. SUMMARY
The synthetic method has been used to determine the solubility of acetylo-toluidine in methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, acetone, chloroform, carbon tetrachloride, benzene, diethyl ether, and water. The heat of fusion of acetyl-o-toluidine has been determined, and an ideal solution curve calculated and plotted. REFERENCES (1) (2) (3) (4) (5)
COLLETT AND JOHNSTON:J. Phys. Chem. 30,70-82 (1926). LAZZELL AND JOHNSTON: J. Phys. Chem. 32, 1331-41 (1928). AND LAZZELL: J. Phys. Chem. 34, 1838-47 (1930). COLLETT WALKER,COLLETT, AND LAZZELL: J. Phys. Chem. 36,3259-71 (1931). Reference 3, p. 1839.
