Influence of Impurities on the Solubilities of HighAMolecularWeight Amine Acetates C. W. HOERR AND H. J. HARWOOD Research Division, Armour and Co., Chicago, I l l .
T
HE solubilities of dodecyl- and octadecylammonium acetates (amine acetates) in benzene and 95% ethyl alcohol (1) and their phase diagrams with water ( 3 , 7 ) have been reported. I n organic solvents these compounds present solubility curves which are typical of the high molecular weight aliphatic nonelectrolytes. Their water systems exhibit the complex behavior characteristic of the long-chain colloidal electrolytes, including evidence of the formation of hydrates and the existence of liquid crystalline phases superimposed upon the crystalline systems.
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measurements: Armac 12 (freezing point, 55.5' i .0.5" C,), the amine acetate derived from distilled 90% lauric acid; Armac C (freezing point, 52.0' i 0.5" C,), the amine acetate derived from coconut oil fatty acids; Armac T (freezing point, 54.0' i 0.5' C.), the amine acetate derived from tallow fatty acids; and Armac HT (freezing point, 69.0' f 0.5' C.), the amine acetate derived from hydrogenated tallow fatty acids. These materials were regular production samples which had been produced by che recently described method ( 4 ) of proportionating liquefied amines and acetic acid directly into a mixing tank with agitation, followed by rapid solidification in order to avoid dehydration to substituted amide which occurs upon long exposure to heat above the melting point of the product.
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Figure 1.
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Y. Armac
Solubilities of Amine Acetates in n-Hexane 0 Armac C A Armae T A Armac HT
0 Armac 12
Although the solubilities of commercial amine salts differ materially from those of pure components, no systematic investigation of the quantitative influence of minor constituents has been reported. This paper presents the results of an investigation of the behavior of the acetates of four types of commercial primary amines-namely, the amines derived from 90% lauric acid, coconut oil fatty acids, tallow fatty acids, and hydrogenated tallow fatty acids. The solubilities of these salts were determined in hexane, benzene, chloroform, 3A alcohol, isopropyl alcohol, and water. The effect of added substances was observed by adding to a pure alkylammonium acetate a variety of materials, the occurrence of which could be expected in commercial amine acetates, such as adjacent homologs, excess amine, nitrile, amide, excess acetic acid, and water. The solubilities of several synthetic mixtures were determined for comparison with the behavior of actual commercial products. EXPERIMENTAL
Purified dodecyl-, hexadecyl-, and octadecylammonium acetates were prepared (1, 5, 7 ) by the additon of the appropriate amounts of acetic acid to the respective highly purified amine's dissolved in anhydrous benzene. The products were recrystallized repeatedly from benzene and air dried. The freezing points were 69.5", 81.5', and 84.5' f 0.1' C., respectively, for the CI2,Cis, and CI8derivatives. The following commercial amine acetates (products of Armour and Co., Chemical Division, Chicago, Ill.) were used for solubility
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Figure 2.
Solubilities of Amine Acetates in Anhydrous Benzene
For symbols, see Figure 1 Upper broken line (-) refers to solubility of octadecylammonium acetate and the lower broken line (- -) refers to that of dodecylammonium acetate
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Early in the experimentation it was found that the commercial samples, with the exception of Armac 12, contained small amounts (probably 1 to 4%) of material which was relatively insoluble in the solvents employed, imparting a haziness to the more dilute solutions. Infrared analysis indicated that this impurity was a substituted amide. Its presence was not considered objectionable in determining solubilities in the nonpolar and moderately polar solvents, but its solubility was so limited in 3A alcohol and in water, particularly in the case of Armac C, that accurate determinations were obscured beyond reasonable limits. Consequently, about 100 grams of Armac C were dispersed in 3A alcohol (25% amine salt) and the mixture was cooled to about -10' C. The insoluble material was removed by filtration aided by the addition of a small amount of Super Filtrol, and the solvent was removed from the filtrate by vacuum evaporation a t about 65' C. The Armac C treated in this manner had a freezing point of 53.5' =k 0.2' C.
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INDUSTRIAL AND ENGINEERING CHEMISTRY
TABLE I. .Imine Acetate
- 20
- 10
QOLCBILITY OF
0
Vol. 44, No. 12
AMINEACETATES IS VARIOUS SOLVENTS
Grams Bmine Acetate per 100 Grams Solvent Temperature, C. 10 20.0 30.0 40.0 50.0
60.0
70.0
m
m
80
100
I X n-HEXANE
Arinac Armao -4rmac Armac
12 C T HT
.. ..
..
.. ..
, .
..
1000 2450 1000 61
CC
m
I .
320
U
, .
..
150
670
m
900 2400 500
m W m
m
..
..
500 61
m
.. ..
..
m
m
I N ANHYDROUS B E X Z E N E
Pure dodecyl ( 1 ) -4rmac 12 Armac C Armac T Ariiiac H T Pure octadecil ( I )
.. , .
..
.. .. ..
.. ..
..
..
..
..
..
.. ..
98
10.5
m m
335
..
..
.. ..
I N CHLOROFORM Armac Brmac Armac Armac
12 C
T HT
Pure dodecyl Armac 12 -4rmac C Arniac C (treated) Armac T Armac HT Pure ootadecyl
9 12 7 1
.. .. .. .. ..
..
..
18 20
27 35
12 3
20
18.3 3.6
32.0 28.2
13:o
..
..
..
7
..
89 3 2
i O . 5
46 61 35 13
78 117 67 23
144 225 150 42
56.7 110 120 160
94 182 330 255 49 23 8.7
154 300 610 425 220 67 28.3
16
8 1.7
300 525 380 78 265 570 1330 850 680 1 a5 66
600 2800 1800 163 490 1900 4500 3500 3200 460 134
W
m
m
m
m
m
460
W
1150
W m
m m m
W
1300 270
W
W W
m
600
.. ..
.. .. .. ..
.. ,.
.. .. I
.
Ix ISOPROPSL ALCOHOL Arinac Armac .4rinac Arinac
12 C
T
HT
8.7
.. .. ..
24.2 2'
..
45.2 39 10
..
87 102 49 3
150 200 145 15
263 400 320 47
545 900 730 112
1900 4800 3200 260
m m m
730
W
W W m
..
.. .. ..
I s WATER Pure dodecyl ( 5 , 7) Armac 12 Armac C (treated) Armac T Armac H T Pure octadecyl
.. .. .. .. .. ..
, .
..
.. ..
..
..
30.7 40.8 37.0
