PURE HYDROCARBONS FROM PETROLEUM Recovery of Aniline Solvent from Distex Hydrocarbon Products by Water Extraction JOHN GRISWOLD', JU-NAM CHEW2, AND M. E. KLECKA' The University of Texas, Austin, Tex. Conjugate liquid-phase equilibria for the separate hydrocarbons, n-heptane, methylcyclohexane, and benzene with aniline and water a t 25' and 50' C. are presented. Three conjugate phases occur in the n-heptane system and in the methylcyclohexane system a t both temperatures, although methylcyclohexane and dry aniline are miscible
at 50" C. For the benzene system, separate hydrocarbon and aniline phases do not appear a t either temperature. The data are useful for design of counterflow extractors to recover aniline from Distex hydrocarbon streams by water scrubbing and also to extract aniline from dirty or corrosive aqueous solutions by means of a hydrocarbon wash.
I
N EXTRACTIVE distillation operations, the hydrocarbon products from the solvent columns contain traces to appreciable concentrations of solvent which the strippers do not remove.
Present address, Illinois Institute of Technology, Chicago 16, Ill.
* Present address, University of Michigan, Ann Arbor, Mich. Present address, Shell Oil Co., Deer Park, Tex.
ANlLlM
Figure I
Figure 3
ANILINE
ANrE
A
Figure 2
Figure 4 1246
June 19SO
1247
INDUSTRIAL AND ENGINEERING CHEMISTRY ANILINE
x
Figure 6
Figure 5
"pg
91
* TIE LW * 3-WSE
Figure 7. n-Heptane-AnllinbWater Sections), 25" C., Wt. %
COMPOSlTlONS
P (Enlarged
This residual solvent may represent a serious economic lose ta the procw, and in any event it must be completely eliminated from the finished product hydrocarbons. In the manufacture of, or in processes using aniline, dirty or corrosive aqueous solutions are sometimes encountered which are impractical to put through a fractionating column. The present investigation waa undertaken to obtain phase equilibria data on typical hydrocarbon-aniline-water sysCms aa needed to predict and design counterflow liquid-phase separation proceeses for recovering aniline from hydrocarbons (and from water). Vartereasian and Fenske ( 4 ) determined liquid-phase equilibria of the n-heptane-methylcyclohexane-adbe system a t 26" C. Binary solubilities of hydrocarbons, water, and aniline are collected in a reference book (8). But no comprehensive ternary
n-Heptane-Mne-Water
Sections), 50' C., Wt.
9%
data have appeared on the desired hydrocarbons with aniline and water. The hydrocarbons selected are n-heptane, methylcyclohexane, and benzene. MATERIALS
The n-heptane waa high-purity material obtained from California Chemical Company (batch No. 15). Ita purity and conatants are certified by the National Bureau of Standards and were checked in this laboratory. The methylcyclohexane waa Dow Chemical Company's technical grade. Treatments with concentrated sulfuric acid and with a nitrating mixture did not alter the refractive index of the ample, indioating the absegce of o l e h and aromatics. An analytical distillation in a Podbielniak Heligrid column showed
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
1248
TABLE I. ?&-HEPTANE SYSTEM Hydrocarbon Phase, U't. % Water Phase, Wt. % Aniline Phase, UTt. ol, nnnAniline Water Heptane Aniline Water Heptane Aniline Water Heptane A. Individual Phase Boundaries a t 25' C. 94.78 91.98 92.35 92.0; 92.32
5.22 3.36 3.19 3.18 3.08
92.03 92.37 91.98 92.34 92.16 92.71 92.77 92.03 93.09 93.32 93.09 93.36 93.57
3.07 2.94 2.93 2.do 2.79 4.83
4.79 4.75 1.30 1.31 1.31 1.25 0.00
0.00
4.67 4.46 4.77 4.60 4.90 4.69 5.09 4.86 5.05 2.46 2.44 3.22 5.55 5.37 5.60 5.39 6.43
3.66 1.03 1.82 1.08 1.0s
96.34 98,88 98.09 98.86 98.81
0.00 0.09 O.O!l 0 (10 0.11
0.00 4.52
0 95 0 00
98 87 99 96
i) 18
1 1 4 7
...
.,
2.07
...
97.83
0.1
2.95
5.3
93.60 88.22 88.63 86.97 97.33
6.40
u.58 5.48 5.33
0.00 6.00 5.80 7.55 7.34
4.20 3.89 3.72 3.71 1.73
95.80 95.80 95.98 95.74 97.82
0.00 0.32 0.30 0.55 0.45
13.72 10.97 3.82 0.00
92.34 87.92 88.01 87.72 88.00 88.15
3.22 3.07 3.04 3.03 2.06 2.04
4.44 9.01 8.92 0.25 9.0% 9.81
1.58 1.58 1.45 0.00
98.01 97.90 98.07 00.91
0.41 0.52 0.48 0.09
, . ,
88 23 87.95 88 11 85.30
3.03
...
2.00 0.00
..
B.
9.76 10.02 9.89 14.70
3.6
...
96.33
0.07
...
c. 0.04
97.01
0.04
93.74
0.00 0.21 0.08 0.02
86.28 88.82 96.10 90.98
c.
6.22
Individiial Phase Boundaries a t 50' C,
, .
.. ..
..
..
..
Tie-Line Data-Water
...
98.36 98.58 95.17 92.50
,..
and Heptane Phases a t 25'
2.1
2.08
024 020 046 000
...
92.6
!.78
0.028
99.98 95.41 !J6.83 97.57 98.04
0 0 0 0
62 40 78 50
C. Three-Conjugate-Phase Compositions a t 25"
A.
0.015 0.066 0,046 0.085
...
B. Tie-Line Data-Water
...
0 01
3.12 2.39 1.93
2.55
...
... . . , ...
.
...
...
...
..,
.
I
... ... ,.. ... , . .
... ..
. , . , .
..
.
I . .
.
.
I
,
I
,
... ... ... ...
...
...
...
...
...
.. ...
,..
...
and Heptane Phases a t 60' C. 96.5
0.5
5.62
0.15
94.23
0.20
88.65
C . Three-Conjugate-Phase Compositions a t 50" C. 87,25
4.4
8.35
4.00
95.6
0.4
11.15
Vol. 42, No. 6
perature was maintained M-ithin 0.05" C. of 25" or of 50' C. by a mercury column thermostat, relay, and electrical heater. The rotating shaft holding the flasks was equipped also with a propeller, and agitation was adequate to maintain uniform temperature at all points in the bath. Single-phase compositions were obtained by titrating a known sample, alternately adding the major and minor components from microburets until the two-phase point was found aceurately. The flask was reimmersed in the bath after each titration to maintain thermal equilibrium. Finally, one drop of reagent would cause the second phase to appear or to disappear, and the determinations are in general accurate to 0.1% or better. The cloud-point behavior of the various phases is quite different. Only in the aniline phase did a literal cloud point appear. The appearance of a a ater phase in a hydrocarbon-phase sample was manifested by the glass taking on a frosted appearance from adsorption of water. The water film could be removed by violent shaking but it reappeared in the same form as soon as shaking was stopped. When a water-phase sample was titrated with hydrocarbon, the appearance of a hydroearbon phase was observed as a thin oil slick or iridescent film on the surface of the water. Tie-line (two-conjugate-phase) and three-conjugate-phase data were obtained by charging known mixtures to the flasks and agitating for 8 hours, then allowing the phases to separate, all in the constant-temperature bath. The 8 hours were found to be fully adequate to obtain equilibrium compositions. Samples of the individual phases were pipetted out and analyzed for aniline content by titration with standardized potassium bromidebromate reagent. Since the aniline concentration locates a point on a phase boundary curve, the entire composition becomes available. But in the
the presence of light impurities but no detectable heavy impurities. The material then was purified by fractionation in a 4 foot X 1 inch diameter column packed with 0.125-inch helices and having an efficiency of about 20 equivalent theoretical plates. The first 25% over was discarded. The purified material tested na: = 1.4205, di5 = 0.7650, aniline point = 40.0' C. The benzene was obtained from industrial pure grade material donated by the Koppers Company. A sample, purified by azeotropic distillation with acetone (1)and refractionated, which waa about 99.7% pure, was used for this work. The aniline was donated by Dow Chemical Company. It was vacuum-fractionated, discarding the fist 25% (chiefly to eliminate water), and was stored over solid sodium hydroxide. The laboratory supply of distilled water was used. APPARATUS AND PROCEDURE
The solubility or phase-boundary compositions were determined by a cloud-point procedure. Samples of various compositions were charged to glass-stormered flasks mounted on B rotaGngshafTt and immersed in an insulated water bath of about 2 feet on a side. The bath tem-
_-
Figure 9. Methylcyclohexane-Aniline-Water(Enlarged Sections), 25' C., Wt. %
INDUSTRIAL AND ENGINEERING CHEMISTRY
June 1950
1249
TABLE 11. METHYLCYCLOHEXANE SYSTEM Aniline Phase, Wt. % nAniline Wator Heptane
Water Phase, Wt. % Hydrocarbon Phase, Wt. % nnWater Heptane Aniline Water Heptane
5
Aniline
W
3'
Individual Phase Boundaries a t 25' C. Sample 1 Sample 1 Sample 1 5.21 0.00 3.60 96.40 0.00 12.02 0.00 87.98 0.09 11.88 0.00 88.12 4.81 0.41 3.53 96.38 0.00 88.1 4.75 0.40 2.88 97.05 0.07 11.9 8.17 11.04 2.88 96.98 0.14 1.73 0.12 3.15 11.57 1.02 98.93 0.05 ... ... 98.15 ... A.
94.79 94.78 94.85 94.79 85.28 85.70 84.94 84.57 04.34 64.27
3.06 1.77 1.30 1.02 1.02
11.24 13.29 14.13 14.64 14.71
84.29 84.27 84.12
1.02 0.88 0.88 Sample 2 94.85 5.15 94.07 4.95
14.69 14.85 15.00 0.00
0.98
94.11 92.46 91.71 91.70 88.93
4.92 4.58 4.54. 4.50 4.07
0.97 2.96 3.75 3.71 7.00 9.73 10.92 11.17 13.00 13.24
93.04 !la. 65 91.98 92.07 89.76
3.72 3.11 3.10 1.52 1.52 ample 3 -' 4.48 4.53 4.45 4.40 4.09
89.19 88.38 87.32 85.87
4.00 3.87 3.73 3.53
6.81 7.75 8.95 10.60
'
1.01 0.50
Sample 2 0.00 0.07 0.28 0.07 0.27 0.07 4.10 0.11 4.10 0.19
0.00
98.74 09.38 Sample 2 99.94 99.85
0.06 0.15
0.08 1.G3 1.45 3.02 3.02 3.34
!)8.82 98.17 98.38 96.81 96.77 96.50
0.20 0.20 0.17 0.17 0.21 0.16
3.54 2.9!) 3.07
96.30 96.88 96.80
0.16 0.13 0.13
,.
...
....
... ... ...
..
.. ..
... ,.. ...
0.01)
..
...
0.25
0.12
1.88 1.82 3.57 3.53 6.15
.. .. .. .. .. .. ..
..
...
... ...
...
.. .. ..
.. ..
.. ..
.. ..
s
E d
z
a
99.93 99.65 99.66 95.79 95.71
< I
8
'
c 30'
0
1
I IO
1
20
I 80
W T -1. A N I L I N E IN H C PHASC
no
lob
Figure 10. Distribution of Aniline between Methylcyclohexane and Water Phases
...
..
. . I
...
...
... ... ... ...
..
..
... ..
. . I
..
F3
Sample 3 11.45 0.20 88.36 1.93 0.03 98.04 1.93 0.04 98.03
...
..
K
... ... ...
40
s
..
t..
...
..
... ...
.. ..
5!30
3 320
.. ..
.*.
...
a r, '0
Individual Phare Boundaries a t 50' C." Sample 1 Sample 1 95.60 0.00 0.00 4.40 6.50 '53.50 6.58 1.18 4.2 95.8 0.00 92.24 95.84 0.00 40.31 4.1G .57.54 2.15 05.19 0.68 4.13 Sample 2 !)6.37 1.01 0.00 0.97 99.63 2.62 10.78 0.33 88.89 98.30 0.65 1.03 1.05 98.07 0.88 10.74 0.66 88.60 0.41 99.06 0.43 26.94 0.54 72.52 26.s4 0.88 72.28 Sample 2 3 45 95 96 0.59 35.30 0.77 63.88 35.26 3.3ti 96 07 0.67 1.04 63.70 43.39 3.35 95.79 0.86 0.91 55.70 43.28 2.55 96.65 0.80 1.15 55.57 49.13 1.03 49.84 1.73 97.68 0.59 49.05 0.71 99.05 0.24 1.17 49.78 50.64 1.13 48.23 0.71 !)9.03 0.26 57.62 1.40 40.98. 0.53 !19.27 0.20 ... .. 57.49 1.63 40.88 59.10 1.57 39.33 .. ... 63.38 1.88 34.73 .. .. 66.34 2.36 31.30 .. 69.81 2.84 27.35 ... 73.31 3.12 23 57 ... 77.23 3.39 19.38 .. ...
fi
A.
.
I
.. ..
.. I .
74.86 76.26 78.49 80.79 82.66 84.35 85.20 86.36 86.98 88.70 88.57 89.35
00.05
20.91 24.24 24.09 35.31 64.08 78.53 77.87 79.11 82.47 84.61
Sample 3 3.96 3.74 4.50 4.90 5.13 5.37 5.41 5.39 5.50 5.31 5.45 5.89 6.06 Sample 4 0.62 0.59 1.18 1.00 1.96 4.21 Sample 5 4.59 4.33 4.94 5.23
21.18 20.00 17.01 14.31 12.21 10.28 9.39 8.25 7.52 5.99 5.98 4.76 3.89 78.48 75.17 74.73 63.69 33.96 17.26 17.54 16.58 12.59 10.16
.. .. .. ..
..
.. .. ..
... ... ,.,
...
Figure 11. Distribution of Aniline between Benzene and Water Phasen
Aniline Phase, Wt. % ' Aniline
Water
89.74
B. 4.26
85.0
5.4
...
..
... ,..
...
... ...
... ,.. ... ...
...
... Noseparate hydrocarbon phase.
0
WT. X ANILINE IN H.C. PHASE
n-
Heptane
Water Phase, Wt. % nAniline Water Heptane
,
Hydrocarbon Phase, Wt. % nAniline Water Heptane
Tie-Line Data-Aniline and Water Phases a t 26' C. 6.0 3.49 96.36 0.15 ...
..
...
At 50° C.
...
... *.. ... t .
0
9.6
3.89
95.71
0.4
...
t . .
Water and Methylcyclohoxane Phases a t 25O C. 2.16 97.64 0.20 4.43
0.15
95.42
0.4
90.06
At 50° C.
.. .. .. .. ..
...
..
so
.,
85.36
2.2
77
...
4.5
96.7
0.8
8.54
Sniline and Methylcyclohexane Phases a t 50° C. ,. 20.09
...
C.
79.79
2.50
...
..
..
Three-Conjugate-Phase Compositions a t 25' C. 12.44 3.45 96.37 0.18 8.72 0.2 15.71
At 50' C. 3.77 95.63
0.6
20.02
0.6
... 91.08 79.38
INDUSTRIAL AND ENGINEERING CHEMISTRY
1250
TABLE111. BENZENE SYSTEM 950
. Organio Phase,
Wt. %-' 'Aniline Water Benzene
c.
50' C. Water ' Organic Phase, Wt. % Water Phase, Wt. % Aniline Water Benzene Aniline Water Benzene Aniline A. Individual Phase Boundaries 4.20 00.00 0.147 99.85 3.66 96.34 0.00 2.89 2.94 97..01 0.054 4.95 0.345 94.71 2.38 15.55 0.307 84.14 2.24 97.72 0.041 2.38 15.53 0.438 84.03 2.24 97.57 0.168 1.76 24.00 0.394 75.61 1.71 98.15 0.142
0.00
0.060
5.10 17.63 17.60 24.41
0.168 0.130 0.303 0.269
99.94 94.73 82.24 82.10 75.32
24.99 29.89 29.85 33.57 33.53
0.393 0.367 0.477 0.452 0.555
74.62 69.74 69.67 65.98 65.92
1.71 1.40 1.40 1.22 1.22
98.02 98.38 98.32 98.53 98.49
0.268 0.220 0.284 0.248 0,292
23.96 26.89 26.85 29.55 40.34
0.531 0.511 0.677 0.652 1.08
75.51 72.60 72.47 69.80 5.858
36.87 36.84 39.86 39.83 42.57
0.527 0.610 0.580 0.658 0.628
62.60 62.55 59.56 59.61 56.80
0.00
99.82
0.180
41.25 49.40 50.68 50.63 48.93
1.06 1.60 1.50 1.59 1.60
57.69 49.10 47.82 47.78 49.47
42.54 44.80 44.75 46.54 46.50
0.717 0.689 0.803 0.777 0.860
56.74 54.51 54.45 52.68 52.64
52.45 52.34 54.42 66.81 67.80
1.49 1.71 1.64 2.64 2.56
46.06 45.95 43.94 30.55 29.64
47.97 47.92 49.64 50.09 53.78
0.836 0.943 0,911 1.29 1.17
51.19 51.14 49.48 48.62 45.05
67.74 68.66 74.57 75.22 75.17
2.64 2.57 3.41 3.32 3.41
53.71 55.53 65.58 66.41 66.34
1.30 1.27 1.94 1.90 2.00
44.99 43.20 32.48 31 69 31.66
... ... ... ...
75.70 79.23 79.57 79.43 80.10
3.33 3.85 3.79 3.96 3.83
67.13 72.70 73.21 73.14 73.63
1.96 2.50 2.45 2.53 2.49
30.91 24.80 24.34 24.33 23.88
... .I. ...
79.49 80.76 80.37 81.51 86.01
4.04 3.79 4.26 4.01 5.08
76.90 77.25 77.17 77.62 76.95
2.83 2.79 2.88 2.83 3.67
20.27 19.96 19.95 19.55 19.38
... ... ...
86.73 86.58 88.92 88.54 88.81
4.82 4.98 4.85 5.35 5.22
80.33 80.22 80.70 79.97 84.86
3.13 3.26 3.18 4.26 3.22
16.54 16.52 16.12 15.77 11.92
88.64 88.98 89.88 90.15 90.04
5.40 5.78 5.56 5.41 5.53
84.46 85.01 84.89 85.47 88.07
3.68 3.56 3.69 3.55 4.09
11.86 11.43 11.42 10.98 7.84
... ... ... ... ... .. .. .. ...
90.22 93.60
5.43 6.40
...
.. .. .. .. .. ..
88.79 88.69 89.02 89.83 90.13
3.84 3.95 3.84 4.31 4.18
7.37 7.36 7.14 5.86 5.69
...
90.04 90.32 90.74 90.93 91.09
4.28 4.16 4.38 4.29 4.50
5.68 5.52 4.88 4.78 4.41
. . .. . . . . . . ...
91.32 94.78
4.38 5.22
4.3
11.21 24.30 35.57 47.34 63.82 75.60 85.94
0.2
.. .. ..
...
...
3:8'
0.00
..... . .
I
.
...
... ... ...
. . I
... .. .. ..
.. .. .. ... ... ... ..... . ... ... ...
.. .. ..
..*
... ... ..* .
I
.
. . . . .
..... . ...
... .
..
... . . . . . . . . . . I .
I
.
.
. . . . . . . . . .
.
I
... ... ... ...
... ...
...
. . . . . . . . . . .. ...
... ...
... I
0.78 1.18 1.71 2.07 2.38 2.75 3.58
.
...
...
. . . . .
I . .
. . . . .
. . .. . . . . . . ... t..
. . . . . . ... ...
. . . . . . ... ...
......
.
... .., ... ... ... ... ...
. . . . . .
B. Tie-Line Data 0.22 15.96 30.35 ... 47.86 ... 59.60 70.55 ... 82.14 0.02 . . .
... ...
... ... ... ... ... ... . . .
heptane system the aniline phase has a node or a point of maximum aniline concentration. On either side of the node there occur two compositions having the same aniline concentration. Samples were made up with different heptane-water ratios, but with aniline contents somewhat lower than that of the aniline phase. When these were brought to equilibrium in the bath and settled, one contained three phases and the other but two, which located the samples according to the proper side of the node. Study of Figure 1or 2 will explain the results of this procedure. Measured volumes of the conjugate phases along
1.76 1.26 7.26 0.00
..
..
..
Phase, Wt. % Water Benzene
95.80 96.70 97.29 97.10 97.75
0.00
97.64 98.24 98.17 99.78
0.60 0.50 0.57 0.22
... ... ... .... .. ... .. .. .. ... ... ...
..
... ... ... ... .
I
.
0.41 0.33 0.52 0.49
..
Vola 42, No. 6 with their compositions permitted the calculation of an aniline balance. Where the sum of the aniline content of the phases did not agree with the quantity of aniline charged, the determination was discarded. Bad runs were caused chiefly by incomplete phase separation. At 25" C., the densities of conjugate aniline and water phases are nearly the same, and they reverse under some conditions. RESULTS AND CONCLUSlONS
The data for the n-heptane, methylcyclohexane, and ben.. zene systems are summarized in Tables I, 11, and 111, re29.62 28.77 spectively. The ternary data .. .. 22.02 .. 21.46 on the individual phase bounda.. 21.42 ries extrapolate to the litera.. 20.97 ... . ..* ture data on the binaries (zero 16.92 ... 16.64 .. ... per cent of one component). .. 16.61 ... The latter data (where avail.. ... .. 16.07 able) are the first and last en.. .. ... 16.47 .. .. ... 15.45 tries i n sections A of the tables. ... .. 15.37 The data are also presented ... 14.48 .. .. ... 8.91 graphically. Figures 1, 2, and .. ... 8.45 3 are the conventional tri... 8.44 angular diagrams for the h e p 8.23 ... 6.11 tane, methylcyclohexane, and . . .. .. .. . . 5.97 benzene systems, respectively, 5.96 .. ... a t 25" C. Figures 4, 5, and 6 5.24 .* ... .. .. 4.56 ... are the equivalent data a t 50" .. .. 4.44 ... 4.43 .. ... .. C. Solubilities in the three hydrocarbon systems increase ... . . 4.35 .. .. ... 0.00 in the order given, and the solu.. ... ... .. ... ... bility in each system increases .. ... ... ... . with temperature. The three.. .. .... .. ... conjugate-phase compositions .,. ... .. ... are fixed a t a given tempera.. .. .. ... ture. Other phase-rule re... straints and properties of tri... .. ... ... ... angular diagram are suf... .. ... .. ficiently well known and need ... .. ... ... ... .. not be elaborated here. The ... .. ... .. behavior of the methylcyclo. . ... ... hexane system in the present temperature range is interest0.4 1.03 ... 0.4 ing. At 25' C., all of its com1.59 ... ..* .* 2.46 ... ... .. ponent binaries are immiscible, 2.62 ... ... .. and there are three separate 3.03 .., ..* 3.45 16.0 ... 0:i individual phase boundaries ... ... just as in the heptane system. But the critical solution temperature for methylcyclohexane and dry aniline is 40 O C. At temperatures above 40' C., methylcyclohexane and aniline are miscible where only a limited amount of water is present. At 50" C. where the aniline is saturated with water or nearly so, there are separate conjugate methylcyclohexane and aniline phases. The heptane system a t both temperatures and the methylcyclohexane system a t 25" C. are presented in enlarged sections in Figures 7, 8, and 9 more clearly to illustrate the shapes of the phase boundary curves. Of more immediate use to extraction calculations are plots of equilibrium aniline concentrations between water and hydro-
.. ..
I .
..
INDUSTRIAL AND ENGINEERING CHEMISTRY
June 1950
carbon or organic phases. These are given for the methylcyclohexane and benzene systems aa Figures 10 and 11, respectively. Because of the low solubilities, this type of plot has not been attempted for the heptane system. Complete extraction of traces of aniline from a hydrocarbon stream by water scrubbing is concerned with the slopes of these curves aa they approach zero. For benzene, the slope is about 2, for methylcyclohexane at 25' C. it is about 5, and for heptane it is considerably above 6. These values indicate that aniline can be scrubbed completely from a hydrocarbon stream by counterflow treatment with water. The relative weight ratio of water to hydrocarbon for complete
1251
scrubbing is about unity for pure benzene and much leea than unity for the other hydrocarbons or their mixtures. Aniline is readily recoverable from water by fractionation (1). BIBLIOGRAPHY
(1) Griswold, et al., Im. ENG.CIIEM., 32,878 (1940). (2) Griswoid and Bowden, Ibid.,38, 609 (1046).
Seidell, A., "Solubilities of Organic Compounds," Vol. 11, 2nd ed., New York, D. Van Nostrand Co., 1941. (4) Varteresaitln and Fenake, IND. ENG.CHBM.,29,270 (1937). (8)
REOEIV8D September 18, 1948. Earlier papers of this series appeared in IND.ENQ.CRSM.,35, 247 (1943); 36,1119 (1944); 38,66, 170 (1946); and 41, 331 (1949).
ETHYLENE OXIDE Hasards and Methods of Handling L. G . HESS AND V. V. TILTON Carbide and Carbon Chemicals Diuleion, Union Chrbi.de and Carbon Corporation, South Charleston, W . Va. Ethylene oxide is stable to common detonating agents when in the liquid state. Recent experiments have indicated that ethylene oxide vapor, however, decomposes explosively when exposed to various ignition sources. The liquid phase muld not be detonated. Satisfactory methods of handling ethylene oxide were found when the explosive nature of its vapor was rewgnied. Results of a research study on its explosive properties are presented, together with suggested procedures for the handling and storage of this material. In order to present a complete discussion, chemical and physical properties, a few uses, and some data on toxieity of ethylene oxide are included.
E
THYLENE oxide, CzH40, is a cyclic ether, the structure of which may be represented as
I
CH/ The three-membered ring is capable of reaction with compounds having a labile hydrogen atom and reacts with such substances aa water, most alcohols, amines, ammonia, and organic and mineral acids. Thus, ethylene oxide is a useful starting material in the preparation of glycols, aldehydes, acids, esters, halides, amines, ethers, and many other derivatives. In a madified Grignard reaction it serves as a convenient reagent for the lengthening of a carbon chaii, two carbon atoms a t a time, Ethylene oxide k also valuable for removing the last traces of acidity in cases where aqueous alkalies may not be used. Ethylene oxide, as a fumigant, is highly toxic to certain insects and, in particular, to their eggs. Because it leaves no residual taste or odor, it is used to destroy certain molds and bacteria in food products. Because it is noncorrosive and has an agreeable odor, it may be used as an industrial fumigant. A nonflammable mixture of ethylene oxide and carbon dioxide, sold commercially as Carboxide fumigant, is convenient for this purpose (6).
TABLE I. PHYSICAL PROPERTIES OF ETHYLENE OXIDE Liquid Apparent speolfic gravity a t 20/20° C. A sp. gr./ At Average wei ht per gallon a t 20" C., Ib. Coeficient of expansion a t 200 C. At 6b0 C. Boiling oint a t 760 mm., C. mm' At(Ap. !40-780 mm., O Cd Boiling point a t 60 mm At 10 mm:: O C. Vapor pressyre a t 2Oo,C., mm. Hg Freeaing point C. Refractive i n d k nn a t 7O C. Viscosity a t 0" C., cp. Solubility in water a t loo C. Solubility of water in, a t loo C. Heat of vaporination a t 1 atm., B.t.u./Ib. Rash point, TAG glass open cup, C.
Reference
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1.3697 0.32 Complete Comalete 245
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