UNIT PROCESSES the resinwas lessthan that in thel monomer mix--ture, which is in direct contradiction to published reactivity ratios ( 1 , 6 ) . However, the vinyl chloride content increases rapidly and becomes equal to that in the monomer mixture a t about 10% conversion. This low chlorine analysis at low conversions may have been the result of increased impurities in the resin due to the high ratio of polyvinyl alcohol and other constituents to the produced copolymer. The solubility of the vinyl acetate in water might result in different monomer reactivity ratios than in the bulk copolymerization of vinyl chloride and vinyl acetate. I n an attempt to reconcile this point the two monomers were introduced in the bottles within 30 seconds of each other in the final runs. The results confirmed the discrepancy. The per cent of vinyl chloride in the copolymer is a function of conversion only (Figure 3). WEIGHT CONVERSION (e) Figure 3. Per Cent Vinyl Chloride in Polymer vs. Weight Conversion Acknowledgment Lauroyl Lauroyl I
Temp.,
1. 2.
60 50
C.
Peroxide, Grams
0.09 0.36
Temp.,
3. 4. 5.
' C.
50 50 50
Peroxide, Grams
0.27 0.18
The authors wish to acknowledge the helpful advice of C. E. Kircher, Jr., and the financial aid of the Detrex Corp.
0.09
Literature Cited Heat stability tests, using a lauroyl peroxide-polyvinyl alcohol syetem, indicate an optimum conversion, before and beyond which heat stability becomes gradually poorer. At 60' C. the optimum is between 5 and 50% conversion. At 50' C. the optimum runs from 10 to 80% or better. Except a t low conversions, heat stability is higher a t 50" than at 60" C. Heat stability decreases with increasing vinyl acetate in the copolymer but is not greatly affected by catalyst concentration. Specific viscosity was found to decrease with increasing temperature and to increase somewhat with conversion. Below about 10% conversion the vinyl chloride content of
(1) Agon, P., Turner, d.,Jr., Rohrer, J., Haas, H., and Wechsler,
H., J . Polymer Sei., 3, 157 (1948). (2) Bankoff, S. G., and Shreve, R. K.,IND.ENG.CHEM.,45, 270 (1953). (3) Bengough, W. I., and Korrish, R. G I Proc. R o y . Soc. (London), A200, 301 (1950). (4) Emmer, E. J., M.S. thesis, Rose Polytechnic Institute (July 1952). (5) Hohenstein, W. P., and Maik, H., J . P o l y m e r Sci.,1, 127 (1945). (13) Mayo, F. R., Walling C , Lewis, F. bl., and Hulse, W. F., J . Am. Chem. Soc., 70, 1523 (1948). (7) Pi-at, J., Mdm. services chzm. &at (Paras),32, 319 (1945). RECEIVED for review Septembei 14, 1953
ACCEPTED Janiiary 22 1954
Diphenylrnercury Synthesis ROY T. McCUTCHAN AND KENNETH A. KOBE Univerrify of Texas, Austin, rex.
Diphenylmercury is a useful chemical intermediate which might enjoy wider application if its price were reasonable. Phenylmercuric sulfide can b e precipitated quantitatively from an ammoniacal solution of phenylmercuric acetate and can be decomposed almost quantitatively to form diphenylmercury and mercuric sulfide. The temperature of decomposition is the most important process variable. This patented process uses only commercially available phenylmercuric acetate and inexpensive inorganic chemicals to produce a high yield of diphenylmercury.
D
IPHENYLMERCGRY is a useful intermediate in the preparation of a number of other organometallic compounds. It reacts with compounds containing reactive atoms or groups, as the halogens, to produce a variety of useful and unusual compounds. Diphenylmercury itself has some specific properties, as do many of the compounds derived from it, such as germicides, fungicides, herbicides, and insecticides. The difficulty and high
April 1954
cost of making diphenylmercury by current organic laboratory methods has curtailed its commercial use. A method is reported here that produces a high yield, up to 97.5010, of diphenylmercury and a t the same time uses only inexpensive, readily available reagents. A cheaper supply of diphenylmercury should allow its use to produce metallo-organic compounds that cannot now be produced commercially and as an intermediate in other reartiom.
INDUSTRIAL AND E N G I N E E R I N G CHEMISTRY
675
ENGINEERING, DESIGN, A N D PROCESS DEVELOPMENT Reactions of Diphenylmercury Diphenylmex cury reacts with metals and metal salts, generally forming the corresponding phenyl metal compound (8, 23, 31). Halides of nonmetals give phenj 1 metalloid halides (11,18,19,31). Inorganic acids generally decompose the diphenylmercury, but monobasic organic acids form phenylmercuric salts, CaHaHgOOCR (16, 28). Oxides of nitrogen and sulfur rcact n-ith diphenylmercury to produce unusual compounds (20, 26, 28), and many other such reactions have been described by R'hitmoie (31).
Table I.
Effect of Temperature PhHpOAc, grams 5.0 Water, ml. $00 Time, inin. 45
Run 31 30
--)-
(I)
This reaction was studied later by Xaynard ( g l ) , who claimed a 95.6% yield of diphenylmercury. However, in five attempts to duplicate these result,s in this laboratory, the best yield obtained was 62%. Even if high yields could tie obtained by this hethod t,here would be several objections to its use. St'annous salts are expensive, and the sodium stannite solution is unstable and difficult t o prepare. The use of pondered zinc to remove the mercury was a troublesome operation, and repeated filt,ration was necesary to clear t'he acetone filtrate before the diphenylniercury could be reprecipitated. Dreher and Otto (8, 10) reacted sodium anialgani with bromobenzene 2PhBr
+ IIgNa?
+ PhnIIg
+ 2NaRr
+ HgCl?
l'iinHg f 2lIgBrCI
-+
(3)
Steinkopf (2s) reported 55 and 67% for different reaction conditions; Borgstrom and Dexar (4)reported X . G a / C ; Blicke and Smith (3) reported 75%; Gilman and B r o m ( 1 2 ) reported 70.6y0; Bachman (2) reported 81%. The reaction of phenylmercuric acet,ate m-ith a sulfide has been known since 1870 2PhHgOAc
+ HeS
+
(PhHg),S i2HOAc
(PhHg,hS --t PhzHg
+ H$3
(4) (5)
though almost no work has bccn done on the reaction. Tlreher and Otto (8)reported t,hat long boiling of an alcoholic solution of potassium sulfide viith phenylmercuric bromide gave diphenylmercury, mercuric sulfide, and potassium bromide. They also passed hydrogen sulfide into an aqueous or alcoholic eolutioii of phenylmercuric acetate (9) and obtained a white precipitate that turned gray and then black as the addit,ion of hydrogen sulfide was cont,inued. The mixture contained benzene, acetic acid, and mercuric sulfide. X o diphenylmercury vias mentioned, and the authors did not know the nature of the initial white com-
676
Granis
Ygd, /C
29.6 43.0 40, ,5 41.2 44.4
Run 33 34
37 36
Run
PhHgOAc, Grams 5.0
Pli~I-Ig, Grains 1.17 3.32 1.683 1,693
Grams/100 MI. HpO 1.0 2.5
12.6 6.25
2 5 3.0
7.5
XaOH/PhHgOAo, Mole Raaio
PhzHg,
Grams
44 45
50.5 51 . 0 42.8
Yield,
70
66.0
-1 fi
88.0 85.4 7t1.4 84.9
$0 54" 53a
Effect of Tiinc
PhHgOAc, grama I\*aOH, grains
Water, nil. Temp., C.
47 56 57
% 44.4
81.2 81.2
47
Run
Yield,
Time, Nin. 45
30 I5
6.25
2.25
230
100
I'hzHg, Grams
2.84
2.86 2.66 S a 2 S (2 0 moles per mole PliHgO4c) instead of HIS.
Yield.
% 86.0
87.7
77.4
12)
Others have used this reaction undrr a vnriet,y of conditions in an effort to increase the yields: Ladenburg ( 1 7 ) report'ed a yield of 27%; Michaelis ( 2 2 ) reportrd 27.2%; Aronheim ( 1 ) reported 467,; Calvery ( ~ 7 )reported 47%, but in "Organic Syntheses" he reports but 377,. The Grignard reaycnt has hccii used in another method of preparation of diphen>-lmercury. l'feiffcr and Truskier ( 2 7 ) prepared it by the folloir-ing reaction with a yield of 447,: 2PhMgBr
I'hzHg,
e.
Effect of Concentration Temp., ' C. 100 Time, miri. 45
There are many known reactions that lead to the formation of diphenylmercury. Some of these have been studied and used for t,he productlion of diphenylmercury. In other reactions diphenylmercury is only a by-product or tJhereaction is purely of academic interest. Several of the more important are discussed here. Dimroth (6: 7 ) reduced phenylmercuric chloride and acetate with sodium stannite. Steinkopf and coworkers (29) reported a 90% yield for the reaction
+ NasSnOe i2SaOH PhsHg + Hg + 2NaX + NanSnOa
,.I e m p . ,
32 29 33
Previous Methods of Synthesis
2PhHgX
Factors Affecting Production of Diphenylmercury in Aqueous Solution
pound. They also carried out a reaction by heating phcnylmercuric acetate in a tuhe with a11 excess of ammonium sulfide. This produced mercuric sulfide, benzene, and ammonium acctatc. Either t'hej- missed the diphenylmercury or the reaction oonditions were severe enough to decompose it. A little later Pesci ( 2 6 ) isolated and st,udied this white inicrmediate compound. He found the mercury and sulfur analyses to agree v\.ith the formula (CeH:Hg)?S. This compound was prepared hy treating a solution of phenylmercuric acetaic in ammoniacal ammonium acetate v i t h either an alkali sulfide or 13-ith hydrogen sulfide. It is a white amorphous powder that is insoluble in water and alcohol. This reaction has been investigated eo that, the iwo steps (Equations 4 and 5 ) can be carried out practically quantitatively. The effects of various reagents and process variables on the yield of diphenylmercury h a r e been investigated. Experimental Reagent. Phenylmerouric acetate can bc prcparcd hy the methods of Kobe and Doumani ( I S ) or Kobe and Lucth ( I S ) . The material used in this work was obtained by recrj-stallization of a commercial grade phenylmercuric acetate from boiling water. It was air-dried and had a melting point of 147.5' to 149' C. Methods of Analysis. lllprcury Ti-aa determined quantitatively by the method of Tabern and Shelberg (30), which uscs fuming sulfuric acid and hydrogen peroxide t o dissolve the samplc. The only change mad(&in their procedure was that a 500-cc. round-bott,omed flask with a ground-glass neck and reflux condenser was used for the solution of tho sample instead of a
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
Val. 46,No. 4
UNIT PROCESSES Kjeldahl flask. The mercury is precipitated as mercuric sulfide by hydrogen sulfide. It was necessary t o determine acetic acid in the presence of hydrogen sulfide in some of the experimental work. The solution containing the two substances was refluxed for several hours to remove the hydrogen sulfide. Completeness of the removal of the hydrogen sulfide was checked by placing lead acetate paper a t the exit end of the reflux condenser. The acetic acid was then titrated to the phenolphthalein end point with standard sodium hydroxide. The accuracy of this method was checked t o 0.001 gram of acetic acid with a solution containing a known quantity of acetic acid. Reaction Conditions. The first experiments were directed toward preparing diphenylmercury directly from the solution of phenylmercuric acetate.
A weighed quantity of phenvlmercuric acetate was dissolved in hot water. The solution was placed in a heated three-necked flask in which it could be agitated while hydrogen sulfide was introduced. The solution was maintained a t the desired temperature, and hydrogen sulfide was bubbled through the solution for a short time to flush out the air; after this a low pressure of hydrogen sulfide was maintained in the flask during the remainder of the desired time. A t thc ond of this time the precipitate was collected on a fritted glass filter and washed with water. The diphenylmercury was extracted by repeated washings with acetone, from which it was precipitated by the addition of about 10 volumes of water. (Control experiments showed this one-step method would precipitate 99% of the diphenylmercury.) The precipitated diphenylmercury was filtered, dried, and weighed. The results are given in Table I. In some evperiments sodium hydroxide was added to neutralize the acetic acid formed and to form sodium sulfide in the solution, or sodium sulfide was added directly to the solution. PHENYLMERCURIC SULFIDE.Phenylmercuric acetate was dissolved in water containing sodium hydroxide (3 moles per mole of phenylmercuric acetate) and hydrogen sulfide passed in a t room temperature until precipitation was complete. The precipitate was filtered, washed with distilled water, and allowed to dry in the air, which took 2 or 3 days because of the gummy nature of the precipitate. Some of the phenylmercuric sulfide was soluble in the sodium hydroxide (or sulfide) solution, and acetic acid had to be added to neutralize the solution and recover all the sulfide. The recovery of phenylmercuric sulfide was practically quantitative; yields were 99.0 and 99.570 for two experiments. Qualitative tests showed that no mercury remained in the filtrate. DECOMPOSITION OF P H E N Y L M E R C U SULFIDE. RIC A carefully weighed quantity (varying from 2 to 2.5 grams) of phenylmercuric sulfide was placed in a round-bottomed flask and 100 ml. of solvent added. The material was refluxed for the length of time given in Table I1 and allowed to cool. Recovery of the diphenylmercury depended on the solvent used. When the solvent was aqueous, the diphenylmercury and the mercuric sulfide were both in the precipitate, which was removed
Table 11. Run 78 60
67 75 76 74 70 41 09
77a 77b 770 79 80 84
April 1954
Decomposition of Phenylmercuric Sulfide Solvent Benzene Toluene Toluene Toluene (wet) Toluene and ethylbenzene Ethylbenzene Cumene Water NaOAo solution Oven Oven Oven Oven Oven Oven (wet)
Time, Min. 35 90 240 35 35
GO 35
30
240 15 85
155 35
150 35
Temp., O
c.
Yield PhtHg,
%
85 119 119 119 125
79.1 92.0 98.0 91.7 84.6
144 162 107
79.9 85.1
. I .
110 110 110 119 119 119
85.2
83.7
87.5 86.3 89.4 89.3 86.0 86.4
100,
70
60 SO 0
40
30 60
80
I00
N#dium Aquoous H e d l u m W I M HpS and H O A C pmmt
Aquoouc
140
I20
160
Temperature, C.
- /r
e5
OISTILLATION
ORYSTALLIZATION
T*I"e"e 1351 c c i T o l u e n e (234 c c i PhpHg Recycle 1 3 2 g J
Figure 2.
A test tube containing i,olucric~ant1 :in excess of diphenylmercury was held at R controlled temperature for scveral hours. Tlic contents w x e stirred Irequently to equiiil)i,ate. Samples of the clear supernatant Rolution \vci.c ~-ithdrawn,weighed, evaporated to drynrs; on R sand bath, and the residue weighed. Tlic solubilitics are given in Table V. 'CESE.
FIL TRATION
j
I
~~~
Ph H 14291
Ph H (5OGgI
Flow Sheet for Small Scale Commercial Preparation of Diphenylmercury
Phenylmercuric sulfide was also decomposed without drying The wet sulfide was filtered on a Buchner funnel and sucked as dry as possible. Then it was placed in a round-bottomed flask fitted with a Dean-Stark or Barrett type water trap and a reflux condenser. The solvent was boiled, and the water was collected in the trap. The diphenylmercury was recovered from the solvent as before. The wet phenylmercuric sulfide was also decomposed in an oven. When this material was heated a large amount of water m-as released from the gel structure of the precipitate. The quantity of water was of the order of 5 ml. for the 3 grams of precipitate and about 55 minutes was required to drive off the a a t e r in the oven. If the precipitate was left in the filter funnel and the funnel placed in the oven for 10 minutes then returned to the suction flask, most of this excess water could be removed and much time saved in the decomposition. The time given in Table I1 started from the time the precipitate was dry. The effect of the process variables-temperature, time, and sodium hydroxide added-is shown in Figure 1. DECOMPOSITION OF DIPHESYLMERCURY. The diphenylmercury formed in the reaction process is sensitive to reaction conditions and reagents present in the solution. A study was made of their effect on diphenylmercury using concentrations similar to those formed in the reaction. Dilute sodium acetate solution, which would form from the phenylmercuric acetate, at reflux temperature, caused a decomposition of only 1.06% of the diphenylmercury added.
678
Table 111.
Reaction of Diphenylmercury with Hydrogen Sulfide and Acetic Acid" 1'hiTTir
HOAc IizS
H?S
- 110.4~
2.0000 2.0000 3.296 3.296
1.5828 I .$?54 2.r.310 3.075
7'3.3 82.3 82.7 93.3
0.324 0.258.5 ,.. . . I
,..
0 ':illlo 0 07335
Benzene odor was present in each exptlriinent
Table IV. Solubility of Phenylmercuric Acetate in Ammonium Hydroxide-Ammonium Acetate-Water H20,
sr1.
YHIOH, MI.
50
I N D U S T R I A L AND E N G I N E E R I N G CHEMISTRY
Y€JaOAc. Grains
PhFIaOrlc
Dissolved, Grams
Little a
Val. 46, No. 1
UNIT PROCESSES ~~
Table V.
Solubility of Diphenylmercury in Toluene Grams PhxHg/Granis Toluene 0.0946 0.1003 0.1591 0.1581
Temp.,
c. 0
27
Average 0 .'0975
o .'i&3 3.62
3.62
99
Discussion of Reactions The solubility of the phenylmercuric acetate in the reaction medium is important. With water alone the yield of diphenylmercury in the one-step method was about the same from 70" to 100" C. Because the solubility of phenylmercuric acetate is greatest a t the highest temperature, 100' C. should be used. A concentration of 3.0 grams of phenylmercuric acetate per 100 ml. water is approximately saturation, and the decreased yield a t this value probably was due to losses in handling. Phenylmercuric acetate is much more soluble in aqueous solutions of ammonium acetate and ammonium hydroxide. A solubility of 3.92 grams in about 52 ml. solution (Table IV) is too great, because the volume of the precipitate of phenylmercuric sulfide retained most of the solution. A more dilute solution was used for the large scale precipitations. Because of the known reaction of diphenylmercury with acids, it was believed that in the one-step process, in which phenglmercuric sulfide was decomposed in contact with the aqueous solution in which it was formed, the acetic acid and hydrogen sulfide present caused decomposition of the diphenylmercury formed in the solution PhsHg $- HOAr PhHgOAc CeH6 (6) PhaHg HzS HgS 2CbHs (7)
+
+
--+
+
+
Table I11 shows that decomposition amounted to 7 to 20%. Hence it is necessary to neutralize these acids by the addition of alkali to the solution. When sodium hydroxide is used the amount should be 3.0 moles per mole of phenylmercuric acetate (Table I). Time has little effect and the reaction is complete in 30 minutes. Because the one-step process would not give yields above 86%, the two steps in the reaction were investigated separately. The precipitation of phenylmercuric sulfide in alkaline solution was shown to be quantitative. The precipitated phenylmercuric sulfide is bulky and holds a considerable quantity of solution. This may be removed slowly by drying. The quantity of solution can be reduced greatly by heating the funnel containing the precipitate. This will destroy the gel structure and free much of the water, which can then be drawn from the precipitate on the filter. If the phenylmercuric sulfide is precipitated quantitatively in aqueous solution, failure to obtain more than 85% diphenylmercury is due to failure to decompose the phenylmercuric sulfide completely or to decomposition of the diphenylmercury after it is formed. The decomposition of the phenylmercuric sulfide can be carried out by heating it in an oven or in an inert liquid medium. If the liquid is a solvent for the diphenylmercury, the separation of the mercuric sulfide from the solution is simple. The boiling temperature of the solvent is important. Benzene produces too low a temperature, and decomposition is not complete. Cumene creates too high a temperature, and the diphenylmercury decomposes. Toluene produces a temperature of 119' C. and a yield of 92%. The best yield was obtained a t this temperature in the shortest time when the phenylmercuric sulfide was decomposed in an oven. The melting point of diphenylmercury is 125" C., and decomposition occurs a t higher temperatures. Apparently decomposition occurs also in the presence of a solvent a t temperatures above 125" C., as evidenced by the lower yields when cumene was used as a decomposition April 1954
medium. Moisture in the phenylmercuric sulfide has no effect on the decomposition, for the same yields were obtained when the moist precipitate was decomposed in an oven and in toluene at 119' C. These facts make possible the laboratory and commercial preparation of diphenylmercury. laboratory Scale Production of Diphenylmercury When small amounts of diphenylmercury are needed for laboratory work, the preparation is made conveniently by drying phenylmercuric sulfide and decomposing it in an oven or in boiling toluene. Seventy-four grams of phenylmercuric acetate were dissolved in a solution of 1 liter of distilled water, 100 grams of ammonium acetate, and 25 ml. of concentrated ammonium hydroxide in a 2-liter Erlenmeyer flask. The solution was treated with hydrogen sulfide until precipitation was complete. The precipitate was collected on a large Buchner funnel, washed Rith distilled water, and then sucked as dry as possible. It was partially dried in an oven a t about 110" C. for 20 minutes, then it was returned to the suction flask for a few minutes. The material was decomposed by heatin it in the oven a t 120" C. for 1 hour. The mixture was allowefto cool, and the lumps were crushed to aid in the extraction. The diphenylmercury was extracted by treating it with 600 ml. of acetone, and the mercuric sulfide was filtered and washed with acetone. The diphenylmercury was precipitated from the solution by the addition of 3.5 liters of distilled water. After standing for 1 hour, the diphenylmercury was collected on a large Buchner funnel, allowed to air-dry overnight, and weighed. Laboratory scale production was also carried out by decomposing the phenylmercuric sulfide in toluene. The precipitated phenylmercuric sulfide was partially dried by washing with a liter of boiling water and pressing with a spatula while suction continued. It was then placed in a 2-liter round-bottomed flask fitted with a reflux condenser and Dean-Stark water trap, and 500 ml. of toluene were added. The material was refluxed for 35 minutes with sufficient heat to remove all the water before this time elapsed. The flask and precipitate were washed with 200 ml. of hot toluene to remove remaining diphenylmercury. The aolution was placed in a distilling flask and the toluene removed by distillation until only about 75 ml. of liquid remained. This solution was removed from the flask and allowed to cool. The diphenylmercury that crystallized at this point was filtered. The remaining toluene was removed by adding 200 ml. of ethyl alcohol and distilling. Diphenylmercury was recovered from the alcohol by drowning in about 5 volumes of water. In the second run made by this method only a small quantity of toluene remained after the f i s t distillation, and it was allowed to evaporate and the residual diphenylmercury was weighed. The results are given in Table VI.
Table VI.
Laboratory Preparation of Diphenylrnercury
Run
PhHgOAc, grams Ha0 liters N H ~ O Hca. N H ~ O A g:ams ~, Decomposition method Temp O C. Time 'kinutes PhrHg recovered, grams Yield, % of theory
86 74.0 1.0 25.0 100.0 Oven 120 60 33.7 86.4
89 37.0 1.0 26.0 30.0 Toluene
90 37.0 1.0 25.0 30.0 Toluene
35 18.6 95.4
35 19.0 97.5
...
...
Small Scale Operation Figure 2 shows the quantities of materials that would be carried through the different operations to produce 500 grams of diphenylmercury. Not included in these quantities are the amounts needed to make the 32 grams of recycled diphenylmercury which is considered to remain in the system from a previous preparation and to recycle in the process. The quanti-
INDUSTRIAL AND ENGINEERING CHEMISTRY
679
ENGINEERING, DESIGN, AND PROCESS DEVELOPMENT ties n-ere calculated from the data obtained in runs 89 and DO using an expected yield of 95.4%. The quantity of wash toluene was not increased proportionately, because the amount used in the laboratory preparation was excessive. About 60% of the diphenylmercury in the toluene can be obtained with each crystallization by cooling the solution t o 27’ 6. The quantity of toluene in the mixture in each case is just enough so that the crystal slurry can be handled. References (1) Ironheim. B., Ann., 194, 148 (1878). (2) Bachmann, W. E., J . Am. Chem. Soc., 55, 2830 (1933). (3) Blicke, F. F., and Smith, F. D., Ibzd., 51, 3479-83 (1929). (4) Borgstrom, P., and Dewar, Margaret AI., Ibid., 51, 3387-9 (1929).
(5) Calvery, H.0.. Ibid., 48, 1009-12 (1926), “Organic Syntheses,’’ Collected Vol. I, pp. 228-9, Sew York, John Wiley 6Sons, Inc., 1946. (6) Dimroth, O., Ber., 35, 2853 (1902). ( 7 ) Diniroth, O., Chem. Zenlr., 1901 I, 449. (S) Dreher, E., and Otto, R., $nn.. 154, 114-15 (1870). (9) Ibid., p. 122. (10) Dreher, E.. and Otto, R., Be?., 2, 542 (1869). (11) Freidliiia, R. Kh., and Sesinejanov, A. N., Compt. w i d . m a d . sci. U.R.S.S., 29, 567-70 (1940). (12) Gilman, H., and Brown, R. E., J . Am. Chem. SOC.,52, 3314-17
(13) Kobe, K. A,, and Dournam, T. F., U. 9 Patent 2,353,312 (July 11, 1944). (14) Kobe, IC. A , , and Lueth, P.F., T m . ENG.CHEX, 34, 309 -13 (1942). (15) Kobe, K. A,, and lIcCutchan, K. T., U. S. Patent 2,628,241 (Feb. 10, 1953). (16) Koton, hi. AI., J . Gen. C h n . (L‘.S.$.E.), 9, 912-16 (193‘3). (17) Ladcnbura,rl., Ann., 173, 151 (1874). (18) Leicester,H. hl., J . Am. Chem. Soc., 5 7 , 1901-2 (1936). (19) I h i d . , 60, 619-20 (1938). (20) hlakarova, L. G., and Nesmejanov, A. IT., J . Gen. Chcin. (U.S.S.R.), 9, 77-9 (1939). (21) Maynard, J. L., J . Am. Chem. SOC.,46, 1510 (1924). (22) Michaelis, A , Ann., 181, 290 (1876). (23) Nad, 51. M., and Kochcshkov, K. A,, ,J. Gen. Chem. ( Lr.S.$.Ii.,, 12, 109-13 (in English 413-14) (3942). (24) Nesmejanov, A. H., and Koaesclikov, K. A., Be?., 63B, 2496 (1930). ( 2 5 ) Otto, Robert, J . pial;l. Choii., [ 2 ] ,1, 184 (1870). (26) Pesci, L., Gam. chim,.ital, 291, 394 (1899). ( 2 7 ) Pfeiffer, P., and Ti.uskicr, P., Ber.. 37, 1125 (1904). (28) Pyman, 1”. L.,and Stevenson, TI. A., Pharm. J., 133, 269 (1934). (29) Steinkopf, W., et al., ,4niz., 430, 41 (1923). (30) Tabern, D. L.. and Shelberg, E. F., ISD. ENG.C m x . , ANAL. E n . , 4, 401 (1932). *(31) Khitmore, F. C., “Organic Compounds of Nercury,” pp. 16570, Sew York, Chemical Catalog Co., 1921. RECEIVED for review August 10,19j3.
(1930).
:iccaPrED Febrriary l:, 1034.
ynthesis o WILLIAM G. DOMASK’
AND
KENNETH A. KOBE
Universify o f Texas, Aosfin, Tex.
Ethylene chlorohydrin has been made for many years, but the secretiveness that has surrounded the process has allowed little specific information to appear in the literature. A study has been made of the effect of several of the process variables on the yields and a comparison made with results from recycle and single column operation. Low temperature operation is undesirable because of extensive formation of by-products. High mole ratios of ethylene to chlorine favor high yields of ethylene chlorohydrin, but the yield decreases as charge rates increase for a given reactor. Physical observations and data indicate that the recycle-type reactor has advantages over the single column reactor in terms of both yield and smoothness of operation. Process variables which must be considered in reactor design are stressed, as weli as conditions and method of operation.
UJIEROUS processes ham? been dcveloped for the synt,hesis of ethylene chlorohydrin. A fen, of the methods border upon the bizarre; many morc are of academic interest only. The most important methods, from an industrial viewpoint’, involve the interaction of ethylene m-ith hypochlorous acid formed by ‘the solution of chlorinc in water. One of the principal uses of ethylene chlorohydrin is in the production of et’hylene oxide which in turn is an intermediate in the synthesis of ethylene glycol and a host of other compounds, including acrylonitrile, ethanolamines, et,hers for hydraulic fluids, and polysulfide rubber polymers. While coileiderable interest has recently been directed to the catalytic oxidation of ethylene t o ethylene oxide, ethylene chlorohydrin will remain an important chemical intermediate for many years. During the industrial expansion after World ’War 11, many firma turned to the production of ethylene glycol through a process that has been practiced in the United States in one form 01‘ another since 1922. As pointed out by Sherwood ( 1 1 ) , the process for the manufacture of ethylene glycol via ethylene 1
Present address, Humble Oil and Refining Po., Baytown, Tex.
680
chlorohydrin is particularly remarkable for t,he serretivcncs? t’hat has surrounded it. operation. There is a considerablc volume of patent’ information but only a rather limited numhcr of reports of laboratory investigations, which deal for the meet part \Tit11 studies of small scale batch preparations. K u r t z ( 1 6 ) first prepared et’hylene chlorohydrin from cthyleiic glycol in 1859 by reacting glycol and hydrochloric acid. Pour years later Carius ( 2 ) reported the more direct synthesis h y thc addition of hypochlorous acid t o ethylene, and this has become the basic react’ion upon which most industrial processes arc founded. In 1919 Gomberg (6) described the synthesis of ethylene chlorohydrin from ethylene and chlorine passed into water. Rhern-ood ( 1 1 ) , AIcClellan ( 7 ) ,and Curmc a n d 3‘oiirisl;ori (3) have described the chlorohydrin process for the production of ct,hylene glycol, and Y~Iurray(8) and Shilov et nl. (19-1,$) h a w described some of the more recent invcstigat,ions of thc eynthcsip of ethylene chlorohydrin. When chlorine dissolves in water it forms hydrochloric acid ant1 hypochloroup acid ‘21, -1- HOH
e HCI
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
+ HOC1
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Vel. 46, No. 4
