Apr.,
T H E J O U R N A L OF I W D C S T R I A L A N D ENGINEERING CHEMISTRY
1920
black look a t first precisely similar. They consist of ultraparticles or agglomerates of two or three particles. After a few minutes, however, a decided difference is apparent. T h e short black has begun t o agglomerate into groups of 2 0 or 30 particles and in an hour over I O O may be grouped together. These agglomerates are loosely held together and may be dispersed by pressing down on the cover glass b u t they come together again in a few minutes. The long black, on t h e contrary, remains completely dispersed after several hours. Fig. 2 shows a short black 18 min. after preparation on t h e slide, Fig. 3 shows the same black after 2 hrs., Fig. 4 is a duplicate of Fig. 3 , magnified 2 0 0 0 diameters. Figs. 5 and 6 show a long black after several hours, magnifications 5 0 0 and 2 0 0 0 , respectively. The concentration of black in oil on the slide is about I p a r t black t o I,OOO,OOO parts oil. Long blacks are usually made with cylindrical burners, a cool flame which tends t o produce a black high in volatile matter. I t seems probable t h a t these adsorbed impurities prevent the carbon particles from agglomerating. I n support of this, we have found t h a t if a long black be treated with steam a t 500’ C. so t h a t the occluded matter is burned off, t h e black forms a distinctly thicker mixture in oil and is seen t o be agglomerated under the microscope. Conversely, if a definite quantity of a short black be treated with a dilute alcoholic solution of tannin and mixed with oil after t h e alcohol has evaporated, i t makes a much more fluid mixture t h a n an equal amount of untreated black. Under t h e microscope the tannin-treated mixture is found t o be completely dispersed and t o show no tendency t o agglomerate. T o summarize, blacks which give long ink probably consist of slightly larger particles t h a n those which make a shorter ink, hence exposing less surface per unit weight a n d taking less oil t o form a mixture of given consistency. Furthgrmore, the difference in surface conditions due t o t h e fact t h a t long blacks contain a high percentage of adsorbed gases, probably influences t h e properties of t h e mixture of the black with oil. Microscopic examination of dilute mixtures of black and oil shows one effect of this difference in surface conditions, namely, the tendency of t h e blacks containing little adsorbed impurities t o agglomerate, while t h e blacks containing large amounts of volatile matter remain dispersed. I
SUMMARY
It has been pointed out t h a t although the present process of making carbon black recovers only a few per cent of t h e carbon in t h e gas, no other process in practical operation produces a material with similar properties. Inability t o secure carbon black would prove a serious blow t o t h e printing industry a n d would probably inconvenience rubber manufacturers a n d others. I n view of t h e diminishing supply of natural gas, developmental work on more efficient methods of production and production from other materials is needed. T h e problem is not a n easy one. Developmental work should probably be directed toward t h e investigation of entirely new methods, such as t h e
33=
thermal decomposition of gas or other hydrocarbons in absence of air, or explosion with CO, COZ,0 2 , or their mixtures. T h e uses of carbon black have been discussed, test methods outlined, and a brief account given of preliminary work on microscopic and chemical differentia-. tion of blacks giving long a n d short inks. ACKNOWLEDGMENTS
We wish t o express our appreciation of the valuable assistance and suggestions of Mr. A. C. Fieldner under whose supervision t h e work was carried out. We appreciate very much the assistance of Mr. J. 0. Lewis, Chief Petroleum Technologist of t h e Bureau of Mines, and of Mr. R. 0. Neal, Chemical Engineer in t h e Bureau of Mines, who made i t possible for one of us t o visit carbon black plants in Oklahoma and West Virginia. THE PRODUCTION OF AMMONIA AND FORMATES FROM CYANIDES, FERROCYANIDES, AND CYANIZED BRIQUETS By G. W. Heise and H. E. Foote U. S. CHEMICAL PLANT,SALTYULE,VIRGINIA Received September 30, 1919
The hydrolysis of the cyanides of t h e alkali or alkaline earth metals b y steam, whereby ammonia a n d formates are produced in accordance with t h e equation MCX 2H20 = NH3 HCOOM, has been known for a long time and was employed on a commercial scale a t least as early as 1843.~ I n t h e past, however, the great demand for cyanides, and their value as compared with ammonia, have prevented this method from achieving any degree of commercial success. Three pounds of sodium cyanide are required for the production of one pound of ammonia, hence i t is obvious t h a t this method cannot compete successfully with the extraction of ammonia from gas liquor unless sodium cyanide can be procured very cheaply. I n recent times the great demand for nitrogen products, a n d their increased cost, has again directed attention t o the hydrolysis of cyanides as a means of obtaining ammonia. Especially in t h e process of nitrogen fixationS with coke a n d soda ash in t h e presence of iron (the present success of which is in large measure due to Bucher,’ who for the first time accurately analyzed t h e controlling factors) , t h e subsequent hydrolysis of the cyanized briquetted product offers attractive possibilities, since the reaction products might be returned directly t o the process, and t h e expense and difficulty of lixiviation and cyanide recovery avoided.
+
+
1 The work described i n this paper was done under the auspices of the Research Section, Nitrate Division, Ordnance Department, U. S. A,, a t Saltville, Va Published by permission of Chief of Ordnance. T. H. Norton “Utilization of Atmospheric 2 B y Newton, in England. Nitrogen,” Dept. of Commerce and Labor, Bur. of Manufacturers, Special Agents Series, Bulletin 62 (191 2). See also Thorpe, “Dictionary of Applied Chemistry.” 2, 539, in which reference t o original literature and patents is made. a Margueritte and Sourdeval, Eng. Patent 1,027 (1860). 4 J. I?. Bucher, THISJOURNAL, 9 (1917), 233, Met. & Chem. Eng.. 16 (19171, 315; Trans. A m . Inst. Chem. E n g , 9 (19161, 335.
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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 CHEMISFRY
Since the data available on t h e hydrolysis of cyanides are meager, especially as regards details of manipulation, most favorable conditions of temperature and pressure, and yields t o be secured, a series of experiments was undertaken on the steaming of sodium cyanide, sodium ferrocyanide, and cyanized briquets. Work was limited t o variations of pressure, partly because it was known t h a t the effect of temperature was being studied elsewhere; partly because we believed t h a t increased pressure would give improved yields. The equation for t h e reaction indicates t h a t there is an actual shrinkage in volume during hydrolysis, two volumes of steam being absorbed for every volume of ammonia formed; hence pressure might be expected t o exert favorable influence on t h e course of t h e reaction. Fortunately, the results of t h e work on t h e effect of varying temperatures have been made available t o us and are summarized and discussed in this report.
Vol.
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No. 4
solution made slightly alkaline with ammonia against standard nickel ammonium sulfate solution, using dimethylglyoxime as an indicator.
76 Condenser
To Pressure
EXPERIMENTAL PART
APPARATUS-A~~ hydrolysis experiments were conducted in autoclaves made of 4-in. wrought iron pipe, large enough t o accommodate a charge of a kilogram of material and a liter of water. The form of apparatus finally adopted is shown in t h e accompanying diagram (Fig. I ) . For a number of experimental runs a t less t h a n 150 lbs. pressure, no water was added, steam being introduced directly from plant boilers through a quarter-inch pipe entering near t h e bottom of the autoclave. I n any case t h e autoclave was immersed in a bath of cylinder oil, kept above t h e reaction temperature, t o obtain t h e desired pressure when water was used inside t h e autoclave, and t o prevent condensation of water when steam was introduced. Pressures were read on a Schaeffer and Budenberg ammonia gauge, reading directly t o 300 lbs., and temperatures were recorded by means of ordinary laboratory thermometers immersed in t h e oil bath, and in some experiments by a mercury-in-iron thermometer (not shown in Fig. I ) inserted near t h e top of t h e autoclave. MANIPULATION-TO make an experimental run, t h e oil bath was brought t o the temperature (determined by experiment) required t o heat t h e autoclave t o a point corresponding t o the desired pressure. The autoclave was then immersed and connected through a quarter-inch union t o t h e condenser. When t h e desired temperature and pressure had been reached, ammonia (together with any excess steam or other gases) was drawn off through an iron ammonia valve into a water-cooled iron condenser, thence into a barrel or large bottle of dilute sulfuric acid, and determined b y titration of t h e sulfuric acid solution. Titrations were made a t frequent intervals in order t o follow t h e course of t h e reaction. ANALYTICAL METHODS-A~~ cyanogen compounds used, including t h e briquets, were analyzed for cyanide content by t h e method of Lundell and Bridgmanl in which t h e cyanide solution or extract is titrated in a 1 THISJOURNAL. 6 (19141. ,. 554.
-I+
, FIG.1
Formates were determined in t h e usual manner by titration with permanganate in warm alkaline solution.' E X P E R I M E N T A L DATA
A-Experiments with Sodium Cyanide The following results were obtained b y passing steam over sodium cyanide at pressures of 50-80 lbs. Expts. I a n d 2 are summarized in Table VI. Expt. 3-The analyses of t h e reaction mass before and after treatment are given in Table I. 1
Lieben, Monatsk , 14, 746; 16, 219.
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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
1920
TABLE I-ANALYSIS OF CYANIDE MASS Sodium Sodium Sodium Sodium Weight
cyanide., cyanate.. formate.. oxalate..
......... .........
......... ......... ...................
Before Hydrolysis 80.77 per cent 5 . 2 2 per cent
..
iii
g.
After Hydrolysis 0.07 per cent 91 :46 per cent Nil 130 g.
Expt. 4-The autoclave smelled strongly of ammonia at t h e end of t h e run, a n d there were other indications t h a t t h e hydrolysis was proceeding as long as water was present, and t h a t better results would have been achieved had more water been present. The analyses before and after hydrolysis are given in Table 11. TABLE 11-ANALYSIS Sodium cyanide.. Sodium cyanate.. Sodium formate.. Weight..
......... ......... .........
................
B-Experiments
CYANIDEREACTIONMASS Before After Hydrolysis Hydrolysis 83.9 per cent 8 . 5 8 per cent 1.99 per cent 90:; per cent i is g. 135 g .
OF
333
tained from cyanized briquets a t 50 lbs. steam pressure, t h e reaction products being essentially ferrocyanide and hydrogen.1 It was found further t h a t , though some hydrogen was also formed a t 1 2 0 t o 150 Ibs. pressure, good yields of ammonia could be secured. Expts. 12 and 13 are sufficiently well described in Table V I . Expt. 14-In this experiment t h e ferrocyanide content rose f r o m 8 per cent in t h e original mixture t o I O per cent in t h e residue, t h e increase corresponding t o a formation of approximately I O g. of sodium ferrocyanide during t h e reaction. No oxalate was detected in t h e residue. Sodium formate, g3-per cent pure and free from carbonate, was recovered-from t h e residue b y extraction.
with Sodium Ferrocyanide
Because of t h e possibility of and tendency toward ferrocyanide formation in cyanized briquets, and t h e resulting decreased yield of ammonia on hydrolysis, Expts. 5 t o I I, inclusive, were undertaken on the steaming of sodium ferrocyanide. Expts. 5 and 6 are summarized in Table V I . Expt. 7-The foregoing attempts to hydrolyze ferrocyanide having resulted in virtual failure on account of frothing, t h e effect of the addition of sodium hydroxide was studied with t h e result noted in Table VI. Expt. 8-In spite of all precautions, frothing occurred after z hrs. when 2 7 . 1 per cent of t h e theoretical yield of ammonia had been produced. Expt 9-A pressure of 300 lbs. developed in 2 hrs. T h e hydrolysis was terminated before its completion because t h e water entirely distilled out of t h e autoclave while t h e reaction was still in progress. Expt. I-TO continue experiments on t h e effect of alkalies, lime was used. A partial analysis of t h e reaction product is given in Table 111.
TIME /N M/NUT€S TABLE111-ANALYSIS OF REACTIONPRODUCT FROM FERROCYANIDE FIG 2-HYDROLYSIS O F SODIUM CYANIDE, F E R R O C Y A N I D E , HYDROLYSIS BRIQUETS Per cent 28.8 Sodium ferrocyanide. Expt. 15 requires no special comment. 12.8 Formate (as HCOONa). . . . . . . . . . . . 13.8 Lime (CaO).
AND
CYANIZED
..............
.....................
Expt. 11-In a similar run where sodium carbonate was employed, t h e reaction product gave t h e following analysis :
Expt. I 6 - T h e routine analytical results f r o m t h e briquets before and after treatment are given i n Table V. TABLE V-ANALYSIS
OF BRIQUETS
TABLE IV-ANALYSIS OR REACTIONPRODUCT FROM FERROCYANIDE HYDROLYSIS
.........................
Sodium ferrocyanide.. Sodium carbonate.. ........................... Formate (as HCOONa)
........................
Per cent 44.3 23.7 28.5
The foregoing experiments show t h a t cyanide can readily be hydrolyzed at comparatively low pressure, and t h a t ferrocyanide is acted upon slowly and with difficulty. Alkalies, other t h a n perhaps caustic soda, did not greatly affect ferrocyanide decomposition.
C-Experiments
with Cyanized Briquets
The briquets were obtained from U. S. Chemical Plant, Saltville, Virginia. Preliminary experiments showed t h a t good yields of ammonia cannot be ob-
Sodium Sodium Sodium Sodium
Before Steaming Per cent 11.2 0.4 23.87 1.38
..................... ..................... .................
cyanide.. cyanate.. carbonate.. .................... ferrocyanide..
After Steaming Per cent 0.0 Trace 29,16 0.16
The experimental results are summarized in Table V I , and typical runs are shown graphically in Fig. 2. DISCUSSION O F RESULTS
For comparative purposes t h e results obtained with 1 C. F.BierbauerandL. S.Finch, U.S . Patents 1,295,262 and 1,295,293, Met. b Chem. Eng., 20 (1918), 431, attempt $0 obviate this difficulty b y dis-
solving crude cyanide as rapidly as possible by blowing pulverized briquet material into a tank equipped with water spray and agitator, rapidly filtering the mixture, and heating the solution with steam under 125 lbs. pressure, the ammonia being allowed t o escape through a relief valve set at 90 Ibs.
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TABLEVI-HYDROLYSIS
OF
Vol.
12, NO. 4
SODIUM CYANIDE, SODIUM FERROCYANIDE A N D CYANIZED BRIQUETS --TEMPERATURESC.-Ammonia
1A
90 per cent NaCN, 300 g .
80
CorreYield sponding Per cent of to Steam Oil TheoretPressure Recorded Bath ical REMARKS SODIUM CYANIDE 70-80 158-161 140-155 165-175 65 Charge frothedinto condenser, stopping .~
2A
90 per cent NaCN, 150 g.
65
50-55
3B 4B
83.2 per cent hTaCN 111 g. 85.5 per cent NaCN: 115 g.
SA 6A
Nad3e(CN)~,.lOHz0,500 g. 94.25 per cent Na4Fe(CN)6, anhyd., 310 6.
7A
94.25 per cent NaaFe(CN)s, anhyd., 150 g. 80 30 g. NaOH 94.25 per cent NaaFe(CN)a, anhyd., 150 g. 120 35 g. NaOH 96.5 per cent NaaFe(CN)e, anhyd., 52 g. 285 90.5 per cent NaaFe(CN)a, anhyd., 106 g. 112 25 g. CaO 96 per cent NaaFe(CN)e, anhyd., 35 g. 170 15 g. NaaCOa
Time Min.
EXPT.
No.
CHARGE
Steam Pressure in Autoclave Lbs. .
run
8A 9B 10B 11B 12A 13A 14A 15B
60 120
+ + +
200 (Av.) 55
145-148
210
93
185-210 150
... ...
215-220 210
100 82
SODIUM FERROCYANIDE 120-135 170-181 180 160-200 120-135 170-181 180 220-240
30 70
+
Powder 23.5 per cent N a C N 440 g. Briquet;, 13.7 per cent N a C G , 730 g. Powder, 23.5 per cent NaCN, 400 g. Briquets, 13.8 per cent NaCN, 750 g.
148-150
125-145
173-184
180-185
200
17
125-135
178-181
178
225
27.1
300-330 300-330
220 220
...
...
250 250
46.6 15.8
Frothing put end t o run Frothing, pronounced odor of NH3 a t end of run Frothing, pronounced odor of NHa a t end of run Frothing, pronounced odor of NHa at end of run 800 cc. water in autoclave 1000 cc. water
300-340
220
...
260
25.3
1000 cc. water
...
50 54 68 90.7
-
CYANIZED BRIOUETS 135 180 180 130-140 180-183 175-178 125-135 178-181 174-177 300 220 ...
55 72 60 38
Trace Little
~
Charge frothedinto condenser, stopping run 500 cc. water in autoclave 1000 cc. water in autoclave. Reaction proceeded until autoclave was dry
Charge frothed into condenser Hydrogen formed Residue free from cyanide 500 cc. water in autoclave. Briauets recovered unbroken 240 92.5 700 cc. -water. Good briquets re16B Briquets, 11.5 per cent NaCN, 1000 g. 41 300-330 220 covered I n experiments marked "A" steam was passed into autoclave; in those marked "B" water was introduced directly,
superheated steam a t atmospheric pressure are briefly summarized in Table V1I.l TABLEVII-STEAMING EXPERIMENTS AT ATMOSPHERIC PRESSURE-PERCENTAGE OF THEORETICAL AMMONIAPRODUCTION 200'C. 30OoC. 400'C. 500°C. 6OO0C.
. . .. .. . . . . . .... ..
Sodiumcyanide . . . . . . . , Sodiumferrocyanide ... . Briquets, 20.5 per cent N a C N .... . . . . . Briquets, 14.7 per cent NaCN .. . . . ,
.,..
0.8(?) 4
56 4 0.5
0.3
6 6
61 5
6 73 6 , 88
6 4
74 91
6 4
54
4
57
4
84
6
99
4 100 4
60
4
47
4
79
6
84
4
85
4
I t should be pointed out t h a t this work differs essentially from our own in t h a t much smaller quantities of materials were used for hydrolysis; whereas we used from I O O t o 1000 g., t h e work in Table VI1 was done with amounts ranging from 2 t o I O g. The results of this series indicate t h a t if steaming is done a t atmospheric pressure, t h e temperature must be raised t o a t least 600' C. t o obtain quantitative yields of ammonia. Although t h e experiments in question were continued for periods of 4 t o 6 hrs., t h e greatest portion of t h e ammonia wa.s obtained in from 3 0 min. to one hour. Using steam under pressure with different degrees of superheating, results were obtained as shown in Table V I I I . TABLEVIII-EXPERIMENTS Gauge Pressure (pounds). -0-
..
Briquets, 20.5 per cent N a C N (saturated steam) 12 20.5 per cent Briquets, Reaction at NaCN. 56 300' C . ......... Briquets, 20.5 per cent Reaction at NaCN. 400' C . . . . . , . . . . . . . . . . . . 75
........
of
STEAM UNDER PRESSURE -25-50-75.-loo-
WITH
3.5
25
30
36
4
44
4
4
61
70
80
4
86
4
4
83
93
100
4
102
4
The above d a t a indicate t h a t with a steam pressure I O O lbs., a temperature of at least 400' C. must be
1 The data in Tables VI1 and VI11 were obtained by Mr. J. A. Beattie of the Nitrate Division, working in the Geophysical Laboratory.
220 220 230
maintained t o secure quantitative yields of ammonia. Our own work indicates t h a t the, exceedingly high temperatures noted above are not necessary for t h e hydrolysis of cyanides on a commercial basis. We have found that a pressure of 300 lbs. without superheat will insure satisfactory results. The hydrolysis of cyanides may be accomplished without great difficulty a t temperatures and pressures which can readily be secured in commercial practice. The reaction proceeds more rapidly a t high steam pressure t h a n a t low, as might be expected. T h a t pressure and not merely t h e higher temperature of compressed steam is a deciding factor is proved b y t h e fact t h a t much higher temperatures are required for hydrolysis a t atmospheric pressure t h a n those recorded in t h e present work. A possible advantage of work a t t h e comparatively low temperatures here recorded arises from t h e fact t h a t hydrolysis proceeds without indications of side reactions, virtually quantitative yields of formate being secured. The available literature indicates t h a t there is little danger of decomposition of formates below z o o o C. Above this temperature oxalates might be formed, and at still higher temperatures oxalates decompose t o form carbonates. (The temperature of saturated steam a t 300 lbs. pressure is 217' C.) I n runs made a t t h e same pressure, better results were secured b y passing steam into t h e autoclave t h a n b y introducing water direct. This is t o be expected, since, in t h e former case, fresh steam comes in contact with t h e reaction mass. The experiments with ferrocyanide showed t h a t hydrolysis takes place very slowly, even a t 300 lbs. steam pressure. Results were not materially benefited b y t h e addition of alkalies, though a t a pressure of 1 2 5 lbs. t h e addition of caustic soda gave indications of an increased yield. The hydrolysis of cyanized briquets t o form ammonia does not proceed very far a t low pressures, t h e best yield obtained a t 1 2 5 lbs. being only 68 per cent.
T H E J O U R N A L OF 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
Apr., 1920
This is due, in a large measure a t least, t o t h e formation of ferrocyanide, probably as follows:
+
+
Fe zHzO = Fe(OH)2 Hz (1) Fe(OH)z 6NaCN = Na4Fe(CN)e 2NaOH (2) The formation of ferrocyanide, which takes place readily enough, seemed further t o be influenced appreciably b y the sulfur content of t h e briquets, in accordance with t h e reaction: 6NaCN FeS = Na4Fe(CN)a Na& (3) At low pressures t h e formation of ferrocyanide in brique\s seems t o progress more rapidly t h a n its decomposition, so t h a t t h e ferrocyanide content materially increases, as shown in Expt. 13. It is therefore clear t h a t t o obtain a maximum yield, ammonia should be liberated from the cyanide as rapidly as possible, preferably- a t a temperature and pressure a t which ferrocyanide is hydrolyzed with appreciable velocity. These conditions were obtained in Expt. 16, in which a maximum yield (92.5 per cent) of ammonia was obtained, and in which t h e ferrocyanide content was actually decreased. The good results obtained a t 300 lbs. indicate t h e desirability of working a t this pressure. I t does not seem advisable t o go much higher in commercial operation. Bierbauer and Finch1 describe a procedure whereby, in t h e presence of much ferrocyanide, all t h e cyanide in t h e pulverized briquet mass is converted into ferrocyanide by digestion with finely divided iron, whereupon t h e mass is filtered, and hydrolyzed a t 80 t o I j o lbs. steam pressure. I n our own work we were unable t o secure satisfactory yields of ammonia b y steaming ferrocyanide a t such low pressures. If condensation in the autoclave is prevented, briquets may be steamed without physical disintegration, and can be returned t o t h e cyanizing retorts. I t has been shown from previous experiments t h a t a t t h e cyanizing temperature of 950" t o 1000' C., carbon monoxide (formed in this case by t h e decomposition of formates t o carbonates) does not interfere in a n y way with t h e nitrogen fixing reaction. It is believed t h a t briquets could be p u t through t h e process three times without disintegration, so t h a t a great saving in t h e cost of briquetting would be effected. It is clear also t h a t unless sodium formate (or oxalate) is t o b e recovered there is no very apparent advantage t o be derived from t h e use of soda ash as one of t h e raw materials for t h e cyanizing process. Barium compounds would naturally suggest themselves because of the relative ease with which they fix nitrogen,2 and even calcium compounds might be applicable. Although no appreciable temperature effect was noted in t h e present work, the fact t h a t t h e reaction is strongly exothermic might prove advantageous both by reducing t h e amount of heat t o be supplied from without and by tending t o prevent condensation of moisture which causes t h e briquets t o stick together or disintegrate. On t h e other hand, a very considerable rise in temperature might induce secondary reactions such as t h e conversion of formate t o oxalate and of t h e
+
+
1LOC.
cit.
Margueritte and Sourdeval, Loc. czt.
+
+
335
latter t o carbonate. I t is also possible t h a t t h e ammonia might be partially decomposed b y being heated in contact with finely divided iron, a reaction which begins a t about 5ooo C., though t h e results of high temperature experiments quoted above do not corroborate this view. It is believed t h a t t h e actual cost of t h e process of making ammonia from cyanide is low. Whether it can be made profitably depends largely on the cost of cyanide in t h e iron-coke briquet mass. I n any case, a t least three times the cost p e f p o u n d of cyanide in t h e briquets would have t o be added t o t h e cost of the process, since 3 lbs. of cyanide are required for t h e production of one pound of ammonia. For example, assuming t h a t cyanide in t h e iron-coke mass costs I O cts. per lb., and t h a t the cost of ammonia production is 4 cts., the total cost of the ammonia would be 34 cts. if t h e formate formed were not recovered. Two dispositions may be made of the formate: it may be left in t h e briquets and returned t o t h e process, or it may be extracted and recovered if market conditions warrant. There are certain advantages t o be gained from t h e first course. If t h e briquets are kept dry during the steaming, they are obtained a t t h e end of t h e process in good condition and may be returned directly t o the cyanizing process. They can probably be passed through t h e complete cycle three times before it is necessary t o rebriquet them. As far as cyanide formation is concerned, formates would be equivalent t o carbonate because t h e former could be converted into the latter on heating. Thus, the entire cost of t h e fresh sodium carbonate otherwise necessary, and one-half t o two-thirds of t h e cost of kneading, briquetting, and drying, would be eliminated. If the formate is t o be returned t o t h e process, t h e whole process might be cheapened somewhat by t h e substitution of barium or possibly calcium for sodium in the manufacture of cyanide. Margueritte and Sourdeval used barium carbonate, carbon, and iron, and state t h a t barium compounds react with nitrogen much more readily t h a n potassium compounds (and presumably more readily t h a n sodium compounds). Thus not only might t h e process of cyanide formation be cheapened through t h e use of cheaper material, b u t i t might also be made more efficient, either b y lowering t h e temperature of t h e reaction or increasing the yield, or both. This suggests s o n e interesting possibilities in t h e way of future experiments on nitrogen fixation along t h e line of comparison between barium or calcium and sodium compounds under the same conditions. On t h e other hand, the formate may be recovered in fairly pure form by lixiviating t h e steamed reaction mass with alcohol. It may also be obtained a t less cost, but in cruder form, by lixiviation with water. T h e formates might be used as a starting point for other compounds, such as esters, formic acid, oxalates, or oxalic acid. SU M MARY
The formation of ammonia from sodium cyanide, sodium ferrocyanide, and cyanized briquets was
336
T H E JOURNAL OF I N D U S T R I A L A N D ENGINEERING CHEMISTRY
studied. Good yields of ammonia were obtained from sodium cyanide b y steaming a t 50 lbs. pressure. A quantitative yield was obtained a t 2 0 0 lbs. The hydrolysis of ferrocyanides proceeded very slowly. A maximum yield of 46 per cent was obtained by steaming 4s/4hrs. at a pressure of 300 t o 330 lbs. With cyanized briquets, yields averaging over 9 0 per cent were obtained in 30 t o 45 min. by steaming at 300 t o 330 lbs. T o obtain satisTactory results with steam a t atmospheric pressure, a temperature of 600' C. was necessary. High temperatures were necessary t o obtain good results with steam a t low pressure. A temperature of 600' C. with atmospheric pressure and 400' C. with roo lbs. pressure gave satisfactory results. At t h e temperatures involved in t h e experiments with saturated steam there were no indications of side reactions, only formates and ammonia being produced.
THE PREPARATION OF HEXANITRODIPHENYLAMINE AND ITS USE AS A BOOSTER FOR SHELL CHARGES LABORATORY, E. I .
DU PONT DE NEMOURS & C O . , CHESTER, P A .
Early after t h e entry of t h e United States into t h e war i t became evident t h a t the country's capacity for t h e manufacture of secondary detonating materials or "booster" explosives for high explosive shells was insufficient t o provide for t h e extensive program planned by t h e Ordnance Department. The material which had been used t o t h e best advantage for this purpose and t h e one apparently preferred above all others was tetryl, or tetranitromethylaniline. Closely approaching this compound in value was tetranitraniline, though t h e latter had some disadvantages connected with its use on account of its questionable stability in t h e presence of moisture. It was evident therefore t h a t in order t o compete with these compounds a n d a t t h e same time supplement the available supply of secondary detonating agents, it would be necessary t o produce a material of similar properties, i. e., high melting point, sensitiveness t o detonation, and power as a detonator, and at t h e same time t o produce it by some method whose simplicity would make it possible t o compete with t h e relatively low prices of tetryl and TNA. Added t o these requirements i t was considered necessary t o develop such a compound from sources other t h a n toluene in order t o conserve as- far as possible t h e supply of this material. A survey of t h e field indicated t h a t t h e symmetrical hexanitrodiphenylamine would probably meet these requirements, though t h e literature was singularly vague on the properties of the material. A careful study was therefore made early in 1918 on t h e manufacture and properties of this compound. The results in a large measure justified t h e hopes which 1 Presented at the 58th Meeting of the American Chemical Society, Philadelphia, P a , September 2 to 6, 1919.
12,
No. 4
had been felt, and i t is probable t h a t had t h e war continued, hexanitrodiphenylamine, or hexil, as i t has been named, would have found a use as a substit u t e for tetryl in boosters for high explosive shells. The first description of this compound was given in 1874 by P. T. Austen,' who prepared it b y nitration of picryl-p-nitraniline, and during t h e same year i t was prepared b y Gnehm2 b y t h e nitration of diphenylamine. Neither of these m,ethods can have any practical value on account of t h e high cost of t h e intermediates involved. The synthesis described in a patent of t h e Chqmische Fabrik Griesheim,3 and elaborated in 1913 by T. Carter,4 offered greater advantages, and i t was this method which was settled on for development. This method as described by Carter depends on t h e reaction of ~,z,~-chlorodinitrobenzen~ with aniline to form dinitrodiphenylamine and aniline hydrochloride, with subsequent nitration b y nitric acid in two stages t o hexanitrodiphenylamine. I t should here be pointed out t h a t a recent article b y Messrs. Hoffman and Dame6 indicates t h a t t h e Bureau of Mines was also interested in this subject, their work in a measure duplicating t h e early phases of our own work.
By John Marshall EASTERN
Vol.
PREPARATION
OF
DINITRODIPHENYLAMINE
The first preparation of dinitrodiphenylamine was made in accordance with Carter's procedure. This method consists of agitating two molecules of aniline with one molecule of chlorodinitrobenzene, t h e reaction beginning slowly a t moderate temperature. There is a t first a slow rise in temperature followed by a more energetic one, which carries t h e temperature t o I 2 5 O C., a t which point t h e charge is drowned in water and extracted with water and dilute hydrochloric acid t o remove excess aniline and by-product aniline hydrochloride. I n t h e laboratory excellent results were obtained with theoretical yields of a product melting at 149' to 152' C. When t h e process was tried on a larger scale, however, it was found difficult t o control t h e temperature properly without drowning t h e charge before t h e completion of reaction, since t h e charge rapidly became so viscous t h a t efficient agitation was out of t h e question. The following more satisfactory method was then devised.6 Two molecules of aniline and one molecule of chlorodinitrobenzene are added t o three times their combined weight of water heated t o 60' C., and t h e mixture is agitated mechanically t o form an emulsion. Steam is then introduced t o raise t h e temperature t o 80' C., t h e reaction beginning during t h i s heating, and coming t o completion in one hour. The dinitrodiphenylamine precipitates in . t h e form of thick clusters of red needles. Agitation a t 80' is continued one-half hour longer t o insure complete solution of aniline hydrochloride, after which t h e charge
c.
Bey., 7, 1248. Ibid., 7 , 1399. D. R . P. 86,295, July 1885. 4 2.ges. Schiess-Sprengsto~w., 1918, 205-251. 6 J . A m . Chem. SOG., 41 (1919), 1013. 6 U. S. Patent 1,309,580, July 8, 1919. 1
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