1066
T H E J O U R N A L O F I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y Vol.
weight of free sulfur is formed for every molecular weight of mustard gas produced. Of the total weight of the mustard gas-sulfur mixture, the sulfur constitutes 16.76 per cent. This sulfur does not precipitate out quantitatively during the course of the reaction. During one process of manufacture (Process A, the 6 0 ” C. process) varying percentages (z.to 8) precipitated out in the form of a slimy, amorphous sludge-the greater the moisture content of the ethylene used, the greater the sulfur precipitation. During the other process (Process B, the 30’to 35’ C. Levinstein process) none of the sulfur precipitated out when the ethylene gas was reasonably dry. The mustard gas produced by Process A had a marked tendency t o precipitate out sulfur on standing, the amount remaining in the mustard gas being about 6 t o 8 per cent by weight of the original crude, i. e . , about 50 t o 60 per cent of the sulfur finally precipitated out, the other remaining in the mustard gas indefinitely. Lowering of the temperature (complete solidification) had t h e same effect, as far as quantity of sulfur precipitated was concerned. However, in the Process B mustard gas, the sulfur had but a n extremely small tendency t o separate out as free sulfur; in fact, most of the material produced with dry ethylene showed only a slight sulfur precipitation after a period of a month (a sample kept for 2 2 mo. in a sealed glass container showed only about a I per cent precipitation), Freezing of the sample also did not cause sulfur precipitation; repeated freezing and remelting of a sample of the crude Levinstein mustard gas had no effect on the sulfur “hold-up.” During the course of some experiments with Process A mustard gas t o remove the hydrochloric acid produced by the hydrolysis of sulfur monochloride and of mustard gas, Venable and Felsingl bubbled moist ammonia gas through crude mustard gas. Immediately crystalline sulfur was deposited in amounts ranging from 5 t o I O per cent of the weight of the mustard gas-sulfur mixture. Dry ammonia passed . through dry mustard gas had no such effect. The melting point of the ammonia-treated mustard gas was never higher, practically always the same, and occasionally slightly lower than before treatment. With the object of ascertaining the effect of ammonia gas upon the crude Process B mustard gas, in which the sulfur hold-up was complete, the following samples were subjected t o a uniform ammonia treatment. Moist ammonia gas was passed through the mustardgas sample for 5 min. The sulfur immediately began t o crystallize out. After cooling, the liquid a n d crystals were allowed t o stand in contact for 6 hrs., and the mustard gas was then filtered througli a tared Gooch filter. The precipitate, consisting of sulfur and a very small quantity of ferric hydroxide, was washed free of adhering mustard gas with CC14 (saturated with sulfur a t room temperature). The Gooch was dried a t I O O O C. and weighed. The ferric hydroxide was then removed with dilute sulfuric acid, and the Gooch reweighed after drying. The following table presents the data obtained: 1
Cleveland Laboratory, Edgewood Arsenal Report, June 18, 1918.
SAMPLE 1
2 3 4 5 6 7 8
Melting Melting Pure Point Point Mustardbefore after Gas Treatment Treatment Content c. O c. Per cent
............. 9.2 ............. 8.7
............. 7.8 ............. 7.0 ............. ............. 87.4 .0 ............. 8.2 . . . . . . . . . . . . . 7.2
9.20 8.65 7.80 6.90 7.40 8.05 8.10 7.20
68.2 71.6 71.5 69.4 64.5 70.0 71.7 71.0
12,
No. I I
Per cent Per cent, Sulfur Efficiency Precipiof Pretated cipitation 6.79 6.54 7.44 7.00 7.10 6.45 7.80 7.20
40.50 39.00 44.35
43.72 42.35 37.46 46.50 42.93
I n each of the samples described above, no sulfur had precipitated out before treatment. The mean weight per cent of sulfur precipitated out was 7.04, which means t h a t only 42 per cent of the supposedly free sulfur was precipitated by the ammonia treatment. The melting points of the samples after treatment were practically the same as before treatment. The pure mustard-gas content was determined on the crude material before treatment by vacuum distillations and melting-point determinations on the distilled product. From the foregoing observed facts and tabulated data, i t is evident t h a t part of the sulfur, a t least, is present in t h e mustard gas as colloidal sulfur, since its removal does not materially influence the melting point of the mustard gas, i. e . , does not cause a raising of the melting point, which i t would have done if t h e sulfur had been in true solution. Of course, there is t h e possibility t h a t the sulfur existed in the mustard gas as a compound, but i t is hardly probable t h a t this compound would have the same melting point as the mustard gas. I t is also quite apparent t h a t part of t h e sulfur is present in the form of compounds, since by no agency whatsoever has i t been possible t o separate all the 16.76per cent sulfur as such from the body of liquid, without resorting t o a vacuum distillation. The sulfur, then, which is in colloidal form in crude Process B must a r d gas, is about 40 t o 45 per cent, while 55 t o 60 per cent are present in the form of compounds. SUMMARY
I-When mustard gas is produced from sulfur monochloride and ethylene, only part of the free sulfur formed separates out. 2-In some cases moisture, freezing, and long standing cause a partial separation of the sulfur. 3-The addition of moist ammonia causes a precipitation of about 4 0 t o 4 5 per cent of the total supposedly “free” sulfur. 4-It is pointed out t h a t the observed facts seem t o indicate t h a t part of the sulfur is present in the colloidal state, while the other part ( 5 5 t o 60 per cent) seems t o be present in the form of compounds. ACKNOWLEDGMENT
The authors desire t o thank Major Wm. Lloyd Evans of the Chemical Laboratory, Edgewood Arsenal, for the timely suggestions he has given. THE INTERSOLUBILITY OF CHLOROPICRIN AND WATER’ By Thos. G. Thompson and John H. Black CHEMICAL LABORATORY, EDGEWOOD ARSENAL,EDGEWOOD, MARYLAND Received May 5, 1920 SOLUBILITY OP CHLOROPICRIN I N W A T E R
Chloropicrin was shaken with a large amount of distilled water t o form a n emulsion. The mixture was 1
Published by permission of the Chief of the Chemical Warfare Service.
Nov.,
1920
T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
permitted t o stand for 3 days a t room temperature in order t o allow the chloropicrin t o settle. The water solution was then maintained a t 25' C. for 6 hrs., and I O O cc. samples were analyzed by the method described below. The solubility of chloropicrin in water a t 0' was determined by shaking thoroughly and standing for several days in a thermostat a t 0'. Samples of the clear solution were treated by the method given below. If portions of this solution were brought t o room temperatyre, a decided precipitation of chloropicrin resulted. Upon cooling, the emulsion would disappear and the solution again become clear. T h e solubility a t 7 5 " C. was obtained by putting ' solution for 2 days in a thermostat maintained the 0 a t 7 5 ' t o 76'. The flask holding the solution was stoppered in order t o prevent evaporation. M E T H O D O F A N A L Y S I S F O R CHLOROPICRIN IN WATER^ -Fifty cc. of alcoholic sodium sulfite were added t o each sample. (This solution was prepared by dissolving I O g. of hydrated sodium sulfite in 2 5 0 cc. of water and diluting with an equal, volume of ethyl alcohol.) The sample was refluxed with a n air condenser t o eliminate alcohol, the. refluxing being continued until all but I O cc. of the solution had evaporated. I t was then diluted t o I O O cc., and a standard solution of silver nitrate added in excess, together with I O cc. of nitric acid. After boiling t o expel the nitrous fumes and to coagulate the silver chloride, the solution was cooled and the excess silver nitrate titrated with a standard solution of ammonium thiocyanate, using ferric alum as a n indicator. TABLEI Grams chlorine in 100 cc. HnO.. , ,
... . . . . . .
c--Temperature 0 25 0.1472 0.1465 0.1468
.. ,. .. .. .
Average equivalent chloropicrin.
.. .. . . . . .
O.ZZi2
O
C
--.
75 0.0739 0.0753 0.0695 0.0674 0.0796 0.0768 0.0674 0.1141
0.1060 0.1048
0.1049
0.1049 0.1042 0.1055 0.1045 0.1621
P
7
SOL U B / L / T Y of
IN
100
6RAM.S
Cff€*I/CIL
@/AT€,? CHf ORP/CR/N
LA8ORclTORI
€DG€WOOD ARS.€NAL
Zo
EDGEWOOD, MD.
\
FIG.2 SOLUBILITY OF WATER I N CHLOROPICRIN
The apparatus consisted of a glass cylinder, sealed a t one end and fitted a t the other with a two-hole rubber stopper. A thermometer was placed in one hole of the stopper and a small glass tube, the length of the stopper, in the other. Through this tube was introduced a glass stirring rod with a loop a t one end. Chloropicrin was placed in the apparatus and very small portions of water introduced. The mixture was slowly heated and constantly stirred until all the water had gone into solution. The apparatus was then cooled and the temperature noted a t which a white cloud appeared in the solution, due t o the precipitation of water. The tube was again heated and the temperature a t which the solution cleared was noted. The average of the temperatures for precipitation and the clearing of the solution was taken as the temperature of solubility. The data collected are reported in Table I1 and illustrated in the accompanying solubility curve (Fig. 2 ) . TABLE I1 Hz0 Gram
YO'
50'
60.
70'
1 TU,?€
FIG.1
Table I gives the results obtained by the analysis of the chloropicrin dissolved in water a t various temperatures. The data are illustrated by the curve in Fig. I . 1 This
method was secured from the Bureau of Mines.
0.1098 0.1098 0.1098 0.1098 0,1098 0.1098
-Chloropicrin--
cc. 29.3 35.8 40.3 53.4 56.0 66.0
G.
Temperature of Mis$bility HzO per 100 G. C. Chloropicrin
48.49 59.25 66.70 88.38 92.68 109.25
55 50.8 48 41 36 32
0.2265 0.1853 0.1647 0.1243 0.1185 0.1003
CONCLUSIONS
I-Chloropicrin is only slightly soluble in water, the solubility decreasing with increase in temperature. is only slightly soluble in chloropicrin, a-Water the solubility increasing with increase in temperature.
