I
JAMES E. KNAP, ROBERT E. LEECH, ALEX J. REID, and WILLIAM S. TAMPLIN Development Department, Carbide and Carbon Chemicals Co., South Charleston, W. Va.
Safe Handling of Alkylaluminum Compounds For safety-keep aluminum alkyls blanketed with inert gas
ALTHOUGH
the reaction of aluminum metal with alkyl halides to produce organoaluminum compounds was recognized nearly a century ago (73), isolation of pure materials from such a reaction mixture was first described in 1924 ( 9 ) . In the interim other synthetic routes were discovered (75) and since the late 1930’s there has been steadily increasing activity in the field of alkylaluminum compounds. Publications have been concerned with preparative methods (2, 7 7 , 74, 75, 25, 27), physical properties (4,5, 70, 76, 27), catalytic applications (70, 72, 78, 79, 27), and chemicai reactions ( 7 , 3, 6, 8, 77, 25, 27) of organoaluminum compounds. Karl Ziegler’s 1952 publication (25) of the reaction of aluminum trialkyls with olefins to form olefin dimers made the first claims of direct commercial applicability for alkylaluminum compounds. Subsequent Ziegler publications have described aluminum refining (27), tetraethyllead production (27), alcohol synthesis (27), and olefin polymerization (26, 27) processes based on aluminum alkyls. These reactions and others such as the polymerization processes of Natta (78, 79) have made alkylaluminum compounds industrially important. Akylaluminum compounds are very hazardous, and the literature contains no enumeration of safe-handling techniques. This information on isobutylaluminum compounds is presented as a guide to handling this type of material.
Hazards Involved The trialkylaluminum compounds contain a very active organometallic bond, which has a high reactivity with “active hydrogen” compounds and with oxygen. The high affinity for oxygen makes the lower members of the series very difficult to handle. However, as a class the trialkylaluminum compounds
874
range from the very hazardous pyrophoric methyl and ethyl compounds to the milder, easy-to-handle compounds of higher molecular weight, such as tridodecylaluminum. Triisobutylaluminum, although less reactive than triethylaluminum, is still difficult to handle. I n controlled testa pure triisobutylaluminurn was not pyrophoric but became very hot and fumed violently when exposed to air. The impure compound has served as a source of ignition for other materials in several cases. The reduction of hazard resulting from replacing one alkyl group of triisobutylaluminum with a chlorine atom to form diisobutylaluminum chloride is noticeable, but not significant enough to allow a change in handling techniques. Replacing a second alkyl group with chlorine has a similar effect. The fire and personnel-burn hazard associated with the low-molecular-weight trialkyls and dialkyl halides of aluminurn are further increased by the possibilities of exothermic addition reactions and metathetical reactions which liberate gases. Thermal Decomposition. Diisobutylaluminum chloride begins to show appreciable decomposition only after 3 hours at 200’ C. The trialkyl compound is much more labile; it decomA1 (iso-CaHg)s -+ AIH(iso-CaHB)n4- iso-C&Is
poses by ejection of isobutene to form diisobutylaluminum hydride (25). The decomposition is undoubtedly an equilibrium which depends on isobutene pressure; however, when the isobutene was removed, the reaction was apparently first order. The effect of temperature on decomposition under these vacuum conditions is presented in Figure 1. Determination of the decomposition rates was based on analytical distilla-
I N D U S T R I A L AND E N G I N E E R I N G CHEMISTRY
tion of triisobutylaluminum at 4 mm. of mercury after aging at the reflux pressures corresponding to temperatures between 70’ and 110’ C. A semilogarithmic plot of half life us. reciprocal absolute temperature was linear : Loglo
= 4918/T
-
13.222
This equation was used in extrapolating the data to 50’ C. Because it is probable that the decomposition is only pseudo first order and is dependent on isobutene
80
70.
60
-
a
8 Li
50
y.
0
2 y”
In
40
P8 0
+
30
w w C 20
10
0. 40
__-
1
I
80 100 TEMPERATURE, *C
0
Figure 1 . Effect of temperature on decomposition of triisobutylaluminum Initial purity 95%
content, rates at atmospheric pressure and above may be lower than indicated in Figure 1. Nevertheless, establishing low environmental temperatures is an important consideration in production, storage, and utilization of aluminum alkyls. Oxidation. One of the potentially most hazardous reactions of triisobutylaluminum or diisobutylaluminum chloride is oxidation, which is highly exothermic and spontaneous on exposure to air. This reaction can be controlled and thus usefully applied (27); however, inadvertent or accidental oxidation could be disastrous. During controlled oxidation the oxygen enters the molecule between the carbon and aluminum atoms, converting one or more of the aluminum alkyl bonds to alkoxide bonds (27). AIR2
+
‘/so2+
RzAI(0R)
This same reaction occurs during partial oxidation, such as might take place in an improperly purged vessel. I n this case only contamination of the trialkyl results. The oxidation reaction is very exothermic and thus introduces further complications, because the trialkyl compound decomposes when heated (Figure 1). Isobutene liberated by thermal decomposition provides an explosion hazard, because of pressure build-up, in closed vessels and a fire hazard in open vessels. The heat liberated and potential violence of the oxidation may be measured by comparing the heat of combustion of triisobutylaluminum with that of noctane. The value for n-octane is 20,591 B.t.u. per pound (20). Using a capsule technique in a Parr bomb calorimeter, a heat of combustion of triisobutylaluminum of 19,620 B.t.u. per pound was obtained in this laboratory. These figures indicate that a triisobutylaluminum fire liberates about the same amount of heat as a gasoline fire, Experiments a t Carbide’s Fire Research Laboratory (24) demonstrated that a fire does not always follow a ground spill or gross exposure of triisobutylaluminum to air. However, the material must be handled as if a fire always resulted. In the absence of flame, a 5-gallon pool of triisobutylaluminum with a surface area of about 56 square feet was dissipated in the atmosphere with the evolution of dense white smoke in 7 minutes and 45 seconds (see Figure 9). Reaction with Compounds Containing Active Hydrogen Atoms. Perhaps the most violent reaction of aluminum alkyls is that with water; it is instantaneous and explosive in nature with the isobutyl oompounds. Alcohols react almost as violently, and it is assumed that other active hydrogen compounds such
Table 1.
Physical Properties of Isobutylaluminum Compounds Isobutylaluminum Diisobutylaluminum TriisobutylDichloride Chloride aluminum
Molecular weight Specific gravity
154.98
2 0 / 2 0 ~c. 30/20° C.
Density, Ib./gal. at 20° C. Boiling point, C. 10 mm. Hg 5 mm. Hg 1 mm. Hg
176.67
198.33
1.1218 1.1116
0.9088 0.9013
0.7859 0.7738
9.34
7.56
6.54
118 105 77
152 138 108
86 73 47
Vapor pressure constants (Antoine) for loglo P = B A - (t
+ c)
A
7.7032 2112.9 197 - 29.8 1.4604
B C Freezing point, O C. Refractive index, 7%; Viscosity, c.p.8. at 20° C.
...
7.6604 2259.69 187
- 39.5 1.4506 5.11
7.4999 1882.43 204 4.3 1.4494 2.39
as acids, thiols, and primary and secondary amines behave similarly. This type of reaction liberates isobutane and copious quantities of a white smoke which is apparently amorphous aluminum oxide. The reactions take place by metathesis :
of electrons around the aluminum atom provides the proper configuration for coordination of aluminum compounds with molecules having an extra electron pair such as ethers, tertiary amines, phosphines, thioethers, and dialkyl selenides and tellurides (4, 6, 8). These coordination compounds, which form Al (is~-ClHg)a 3HzO with the evolution of heat, are very AI(0H)a 3 is0-C4”lo stable and lack some of the properties (particularly catalytic properties) of AlCl (iso-C4Hg)2 2Hz0 + AI(OH)zCl+ 2 ~ s o - C ~ H I ~the pure alkyls. Only the coordination compounds of the methyl alkyls have In addition to the violent and exothermic been much studied (6, S), but from these nature of the initial reaction, the libstudies the heat of coordination can be eration of the gaseous phase could be a estimated at about 400 B.t.u. per pound hazard ,from a pressure or combustion of triisobutylaluminum. This amount standpoint. This renders the use of of heat is liberated when the alkyls come water, steam, or ammonia as heat transin contact with ethers, tertiary amines, fer media a questionable practice. etc. Reaction with Oxygenated Compounds. Many compounds which conPhysical Properties tain oxygen but no active hydrogen atom react with aluminum alkyls to form stable The physical properties of triisobutyladdition or reduction products. Oraluminum, diisobutylaluminum chloride, ganic carbonyl compounds (7, 77, 27) and isobutylaluminum dichloride are and some of the oxides of carbon, nitropresented in Table I. These samples gen, and sulfur ( 3 ) are known to react. had been prepared by repeated distillaLiberation of heat is the important contion of material of a t least 95% purity, sideration, because no gases are evolved. the criterion of final purity being a Reactions with Halogens. Alkylsharp freezing point. The gravities aluminum compounds react rapidly with were measured in sealed, constantchlorine; in fact, this reaction is the basis weight pycnometers and refractive inof a process for producing alkylaluminum dices obtained by the use of a nitrogendichlorides (7). blanketed Pulfrich refractometer. Boiling point was measured by disRzAlCl C11 + R(AlC1z RC1 tilling 100-ml. samples in a specially I t is assumed that other molecular designed, short-path still; the midhalogens react similarly. Alkyl halides point of the distillation was used as the also react with aluminum alkyls. Cardata point. Pressures were measured bon tetrachloride reacts rather violently by a dibutyl phthalate manometer backed by a reference vacuum. A Pirani and, although none of the reaction prodgage was used to check on the vacuum. ucts has been isolated, the chlorine is Each determination was made on a assumed to attach to the aluminum (3). fresh sample of material. The experiCoordination with Electron-Suffimental boiling points and pressures were cient Compounds. The “open sextet”
+
+
+
+
+
VOL. 49, NO. 5
MAY 1957
875
of the triisopropyl compound [2O C. (27)J, rather than low like those of the linear trialkyls. These boiling and freezing points may indicate that the triisobutyl compound is monomeric like triisopropyl- rather than partially or totally dimeric like trimethyl-, triethyl-, and tripropylaluminum (27). laboratory Handling Techniques
Figure 2. Laboratory aluminum alkyls
transfer
of
Note presence of smoke in receiver
correlated by the Antoine equation and the tabulated vapor pressures were calculated by that equation. The boiling point of triisobutylaluminum is lower than that of triethylaluminum. At 10 mm. of mercury, for example, triethyl boils at 97’ C. [this value agrees with the data of (76)], while triisobutylaluminum boils at 85’ C. The freezing point of triisobutylaluminum (4.3’ C.) is high, like that
Various techniques have been developed for handling small amounts of triisobutylaluminum and diisobutylaluminum chloride on a laboratory scale. Use of these techniques has rendered the handling of aluminum alkyls a safe operation; however, there is no substitute for alert caution. The watchwords for handling aluminum alkyls are: “Keep them blanketed with inert gas.” Under an atmosphere of nitrogen or argon and out of contact with reactive materials they are safe. High purity (dry, deoxygenated) nitrogen and argon have been used successfully as purge gases. Both gases give rise to white fumes from the equipment vents during purging, but no inert purge gas has been found that avoids this phenomenon. The surface area exposed determines the amount of smoking. The most convenient method of handling these materials in the laboratory is in filter flasks. The side arm is connected by rubber tubing to a glass tube through a stopper in the neck of the flask (Figure 4). The stopper is sealed to the flask (General Electric Glyptal alkyd resin No. 2592 was used); for greater safety the stoppers may be wired on. One of the advantages of this container is its adaptability to transfers. A purge stream can Figure 3.
be introduced at the neck and vented a t the right side arm. Once the purge is established, the liquid can be poured out through the side arm. The purge should be re-established at short intervals, by erecting the flask so liquid flow stops, to prevent pressure from building up in the reservoir vessel. This pouring technique is demonstrated photographically in Figure 2. The purge gas used was reduced from cylinder pressure to about 2 pounds per square inch gage. I n handling material in these flasks it is most important to realize that there is a slight build-up of pressure in the flask on standing-at ambient indoor conditions about 2 pounds per square inch. There has never been a serious build-up of pressure, but it is sufficient to cause a vapor effluence when the rubber tubing at the neck of the flask is removed. This phenomenon, which seems unavoidable, makes it imperative to keep the tube through the stopper from dipping into the liquid. If the tube enters the liquid, the alkyl may be forced out through it by the pressure in the flask when the rubber tubing is removed at the neck. A dry box is used at this laboratory for manipulations involving transfers to or from equipment which cannot be continuously purged. The “air lock” is shown open in Figure 3, where the inert gas bubbler and the internal pressure manometer are also shown. This device has been used for filling infrared cells, ampoules, viscometers, centrifuge bottles, and oxidation cells, and for insertion and removal of corrosion coupons from alkyl exposure tests. Small amounts of alkyls can be transferred by a hypodermic syringe, even in air, if the needle is wiped before removal from the
Dry box
Figure 4. Dry box used for handling aluminum alkyls in totally inert atmosphere
876
INDUSTRIAL AND ENGINEERING CHEMISTRY
H A N D L I N G ALKYLALUMINUM COMPOUNDS dry box and the tip is protected by inserting it in a cork or rubber stopper to prevent oxidation at the opening. In laboratory reactions, equipment having spherical, ground-glass joints should be used wherever possible. Clamping these joints helps ensure tightness. Stopcocks are to be avoided, particularly in contact with the liquid, to prevent freezing and leakage. When stopcocks are necessary, a secure clamp should be used to prevent leakage; no cure for freezing has been found, because all greases are attacked to some extent. Destruction of Alkylaluminum Compounds. When it is necessary to destroy small amounts of alkyls or wash out equipment left “hot” by them, a mixture of about 25% isopropyl alcohol and butyl ether is useful. If the quantity of alkyl is large and the reaction gets too violent, the isopropyl alcohol boils out and can be replaced when the mixture cools. Water can be safely used for destroying alkyls only when a diluent such as a hydrocarbon solvent can be added in large quantities. Large quantities of these materials (above 1 gallon) can be Safely and conveniently destroyed by dumping in a location where a fire is no hazard or by deliberate burning.
Figure 5.
Steam hose exposed to triisobutylaluminum Leh.
New
Right.
or
After 1 month of service
on a
Scale
Of Construction* steel appears to be a satisfactory material of construction for either triisobutylaluminum or diisobutylaluminum chloride. The results of corrosion tests on a variety of metals are presented in Table 11. None of the materials tested was detrimental to the aluminum compounds,
Table II. Corrosion by Triisobutylaluminum and Diisobutylaluminum Chloride Rate of Exposure Time, Hours
Metal Mild steel 18-8, Type 304 18-8, Type 316 Copper, Type 103 Chemicallead Plasticap-coated steel
Temp.,
O
C.
Penetration, Inch/Year
Type of Attack
TriisobutylaluminumRefluxing at 15 Mm. Hg 2 90 0.0066 Very fine pitting where exposed to liqulid 2 90 0.0007 None apparent 2 90 0.0050 None apparent 2 90 Nil None apparent 2 90 0.0337 None apparent 2 90 , None apparent
with the possible exception of chemical lead. Laboratory experience has also demonstrated the inert nature of solder and silver solder toward triisobutylThe best flexible tubing for use with these materials is polyethylene, although it is not completely satisfactory for isobutylaluminum dichloride. Tygon and rubber tubing are very satisfactory for service in contact with the vapor above the compounds and for service involving intermittent contact with the liquid, but both harden on continued exposure. After hardening, the rubber begins to crack internally (Figure 5). Steam hose was very satisfactory in development-scale operations; however, freque& examination and replacement should be practiced. Special Equipment a n d Techniques. The only special pieces of equipment
..
Triisobutylaluminum at Superatmospheric Pressure Mild steel 1
15
120
0.0004 0.0004
None apparent
15
120
0.0002 0.0003
None apparent
1s
120
2 18-8, Type 304
1 2 18-8., Tvoe 316 1 2
.-
Mild steel 1 2
0.0006 0.0006 Distilled Diisobutylaluminum Chloride 70 days 70 days
Ambient, indoor
Nil Nil
None apparent
None apparent None apparent
Crude Diisobutylaluminum chloride Mild steel 1 2
79 days 79 days
Ambient, indoor
Nil Nil
Very light etch Very light etch
64 days 64 days
Ambient, indoor
Nil Nil
None apparent None apparent
64 days 64 days
Ambient, indoor
Nil Nil
None apparent None apparent
Hastelloy B 1
2 Hslstelloy D 1
2
Figure 6. Cylinder for intraplant transfer of triisobutylaluminum or diisobutylaluminum chloride VOL 49, NO. 5
M A Y 1957
877
Figure 7. inder
Top view of transfer cyl-
used for handling alkylaluminum compounds were transfer cylinders for intraplant shipment (Figures 6 and 7). Their over-all height is 4 feet and they hold approximately 12 gallons. The top has four connections: a relief valve (set to relieve at 25 pounds per square inch), a gage. a Hoke purge valve, and a Hills-McCanna diaphragm valve for filling. The diaphragm valve is flanged and is shown capped with a plugged flange ready for transit. The bottom value is a Durco plug cock with a Teflon liner; it has given excellent service in contact with aluminum alkyls. It is a quick opening and closing valve and as such provides immediate off-on control in case of emergency. This valve, too, is sealed Tvith a plugged or blind flange in transit.*
The nature of aluminum alkyls makes layout and piping of facilities very complicated. Inasmuch as lines cannot be opened to the air, and “drained” lines are not safe for operators or fitters to work on, means must be provided for isolating, purging, and cleaning all lines and equipment, This necessitates multiple valving arrangements and networks of inert gas purging lines with entries for deactivating solutions and washing liquids for nearly all permanent or temporary lines in a unit, to allow one line or section to be worked on without deactivation of the complete system. Even sampling lines should have a nitrogen inlet for purging, so removal of the sample container-e.g., filter f l a s k 4 o e s not leave a dripping, smoking line. Filtration. During filtration development studies it was discovered that diisobutylaluminum chloride reacts violently with cloth filter cartridges, even under a nitrogen atmosphere. and leaves a charred residue of the filter. Under similar conditions neither cheesecloth nor industrial filter paper reacted, but oven drying and thorough purging of the filter cartridges did not eliminate the charring. It was therefore concluded that the reaction took place with the binder in the filter and not with cellulose or adsorbed air or moisture. Porous stainless steel filters and ceramic filters perform satisfactorily in this service. When equipment has been deactivated with isopropyl alcohol and butyl ether and washed or steamed, it is very important to remove all traces of those compounds and leave the equipment clean and dry. One unfortunate incident occurred when some of these reagents were left in a Micro Metallic filter. When the filter was placed in operation the evolution of isobutane, produced by reaction of the residual solvents \vith diisobutylaluminum chloride, caused rupture of the filter element. The broken filter is shown beside a new one in Figure 8. Personnel Protection Burns. Range finding tests with triisobutylaluminum and diisobutylaluminum chloride were performed at Mellon Institute (23) to determine the general animal toxicity of the com-
Figure 8. Filter ruptured by reaction o f diisobutylaluminum chloride with residual cleanup reagents
878
INDUSTRIAL AND ENGINEERING CHEMISTRY
Figure 9.
pounds. The data indicated no difference between the two. Undiluted material burned holes in adhesive tape, cloth, and polyethylene sheeting in the presence of air. Similarly. “holes are burned in the skin wherevei the undiluted compound makes contact” (23). A 40y0dilution in mineral oil burned rabbit belly, but 20, 10, or 570 dilutions caused no reaction. Four grams of a 5% dilution (in mineral oil) per kilogram of body weight was all rats could ingest without violent rupture of the stomach. Experience at South Charleston has been that all personnel burns were superficial, very slow healing, and extremely painful. Affected areas should bc flooded immediately, preferably with water, to remove the material and lessen reaction with the skin. A person so burned should be taken to the nearest dispensary because of the intense pain. The Medical Department at this plant has authorized the immediate intramuscular administration of ’/4 grain of morphine to personnel burned by triisobutylaluminum or diisobutylaluminum chloride. Until the morphine takes effect, immersion of the affected part in ice water gives some relief. After the narcotic takes effect, the injury may be dressed as usual. The issuance of Demerol as a sedative to take home has also been authorized. For the protection of personnel, strict inspection schedules should be set up, particularly at valve bonnets, packing glands, gasket seals, and other points where leakage conceivably might occur. All personnel in the area should wear caps (hard hats may be better). Operating personnel should wear full-face shields whenever transfers are being made. Operators working around opaque equipment should wear gloves ; even when the materials can be observed this is a good precaution. Laboratory aprons protect clothing. No cloth has been found that resists these compounds, but rubber and leather are fairly resistant. Vapor Toxicity. Vapor toxicity tests on rats were performed at Mellon Institute (23) under conditions of vapor concentration simulating spills of 1 gallon of alkylaluminum compound per 2000 cubic feet of volume. Under these conditions, TWO of six rats exposed
Ground spill of 2.5 gallons of triisobutylaluminum
HANDLING ALKYLALUMINUM COMPOUNDS
Figure 1 1. Extinguishing triisobutylaluminum ground spill by dry chemical extinguisher Figure 1 0. Extinguishing burning triisobutylammonium ground spill by carbon dioxide
to the fumes from diisobutylaluminum chloride for 1 hour died the same day of lung hemorrhage. The toxicity of fumes from triisobutylaluminum was somewhat less, but in either case it was termed “moderate.” The animals were in obvious distress, which indicates that unconfined humans might be forced from an affected area. The fumes are white and have an unusual musty odor, and so are detectable even in small concentration. All personnel exposed to these fumes should report to the dispensary to be examined for possible lung or bronchial injury. In addition to possible lung damage, an attack of “fume fever” is a possible result of inhaling these vapors (22). Fume fever is a physical reaction of the lung to massive inhalation of very fine particles (15 mg. or more per cubic meter of air), and like severe influenza, may produce 36 to 72 hours of agony in the victim. Reasonable ventilation of all enclosed areas is sufficient protection for daily operation. In case of emergency, adequate protection for short exposure would be provided by a gas mask. General-purpose canisters are recommended for protection against vapors from the decomposition of triisobutylaluminum, but acid canisters in the case of vapors from the chlorides because of the possible presence of hydrochloric acid. Fire Extinguishment The problems of what to do about ignited aluminum alkyls is being studied at Carbide’s Fire Research Laboratory (24) on fires involving samples ranging from 0.5 pint to 5 gallons in various degrees of confinement. Burning triisobutylaluminum liberates about 3300 B.t.u. per minute and presents a considerable extinguishment problem. Small fires that occur in laboratory spillage, or are confined as in an opentopped vessel, such as a bucket, can be extinguished with high rates of application of carbon dioxide; for general use
on such fires, however, “dry chemical” extinguishers are more effective. Figure 9 shows an unignited ground spill of 2.5 gallons with an exposed area of about 80 square feet. After ignition, 5 to 7 seconds was required to extinguish the fire with dry chemical application. Reignition did not occur but could be brought about by an ignition source. Half the contents of a 30pound dry chemical extinguisher put out two fires. In contrast to those results, a 1.5-gallon ground spill was not extinguished in 33 seconds by emptying a 15-pound carbon dioxide extinguisher. Carbon dioxide offers the fireman less protection (Figure 10) than the radiant-heat-absorbing cloud afforded by the dry chemical extinguisher (Figure 11). Water and aqueous, mechanical foam have been applied to fires and spillages of 5 gallons of triisobutylaluminum. Although water extinguished fires when applied a t the 1 gallon per minute per square foot of surface, the reaction with water was extremely violent. The explosions resulting from the foam application were more intense than those produced by water. Neither agent was a satisfactory fire-extinguishing medium. Further tests are in progress. Acknowledgment Thanks are accorded to C. P. Carpenter and H. F. Smyth, Chemical Hygiene Fellowship, Mellon Institute, and to D. H. Way, Fire Research Laboratory, Carbide and Carbon Chemicals Co., for permission to publish their data. The cooperation of J. C. Zobrist in evaluating corrosion samples is also gratefully acknowledged. literature Cited (1) Adkins, H., Scanley, C., J . Am. Chem. SOG.73, 2854-6 (1951). (2) Baker, E. R. B., M.S. thesis, Ohio State University, 1950. (3) Baker, E. R. B., Ph.D. thesis, Ohio State University, 1953. (4) Baker, E. B., Sisler, H. H., J. Am. Chem. SOC.75, 4828-9 (1953).
Bamford, C. H., Levi, D. L., Newitt, D. M., J . Chem. SOC.1946, 468-71. Coates, G. E., Ibid., 1951, 2003-1 3. Coates, H., Hunter, W. H., Topley, B. (to British Minister of Supply), U. S. Patent 2,712,546 (July 5, 1955). Davidson, N., Brown, H. C., J . Am. 64, 316-24 (1942). Chem. SOC. Grignard, V., Jenkins, R., Compt. rend. 179, 89-92 (1924). Grosse, A. V., Mavity, J. M., Division of Orcanic Chemistrv. 95th Meeting, XCS, Dallas, Tex.‘, April 1938. (11) Grosse, A. V., Mavity, J. M., J . Org. Chem. 5 , 106 (1940). (12) Hall, F. C., Nash, A. W., J . Inst. Petroleum Technol. 23. 679 (1937): ,, 24, 471-95 (1938). (13) Hallwachs and Schafarik, Anti. 109, 206 (1859’). (14) Hnizda, V. F., Krause, C. A., J . Am. . Chem. SOC.60, 2276 (1938). (15) Jones, R. G., Gilman,. H.,. Chern. Reo. 54,.835-90 (1954). (16) Laubengayer, A. W., Gilliam, W. F., J. Am. Chem. SOC.63, 477-9 (1941). (17) Meerwein, H., Hinz, G., Majert, H., Sonke, H., J . praXt. Chem. 147, 226-50 (1936). (18) Natta, G., J . Am. Chem. Soc. 77, 1708-10 (1955); J . PoZymei Sci. 16, 143-54 (1955). (19) Natta, G., Pino, P., Farina, N., Symposium on Macromolecular Chemistry, Milan, Italy, Sept. 27, 1954. (20) Perry, J. H., (ed.): “Chemical Engineers’ Handbook,” 3rd ed., p. 244, McGraw-Hill, New York, 1950. (21) Pitzer, K. S.,Gutowsky, H. S., J.Am. Chem. Soc. 68, 2204-9 (1946). (22) Smyth, H. F., private communication, May 4, 1956. (23) Smyth, H. F., Carpenter, C. P., unpublished reports, Chemical Hygiene Fellowship, Mellon Institute. (24) Way, D. H.; unpublished data, Carbide and Carbon Chemicals C o . , Fire Research Laboratory. (25) Ziegler, K., Angew. Chem. 64, 323-9 (1952); Chimica e industria ( M i l a n ) 34, 520-7; Brennstoff Chem. 33, 193-200 (1952); GZuckauf 88, 3802 (1952). (26) Ziegler, K., Brennstoff Chem. 35, 321-5 (1954); (tr.) Petroleum Rejner 34, 111-16 (1955). (27) Ziegler, K., athers, Angew. Chem. 67, 424-6 (1955). RECEIVED for review July 20, 1956 ACCEPTED November 14, 1956 Division of Industrial and Engineering Chemistry, 130th Meeting, ACS, Atlantic City, N. J., September 1956. VOL. 49, NO. 5
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879
