Manufacture and Uses o f Ethylene Oxide and Ethylene Glycol P. P. McCLELLAN Jefferson Chemical Company, Znc., New York 22, N . Y . T H Y L E S E oxide was This paper describes commercial methods for the prosuperficially be explained as first reported by Wurtz duction of ethylene oxide and ethylene glycol in this counoccurring by the elimination in 1859 ( 4 2 ) as being try and reviews the more important properties and uses of of one molecule of water from prepared from the reaction ethylene oxide. In a discussion of the preparation of two molecules of chlorohyof potassium hydroxide on ethylene oxide via ethylene chlorohydrin the fundamental drin, but i t scarcely seems ethylene chlorohydrin. The chemical reactions together with those leading to the credible that such a reaction chlorohydrin was made by major by-products are given and the application of this could take place under the the action of hydrochloric process on a commercial scale is illustrated. The preparaconditions normally encounacid on ethylene glycol. tion of ethylene oxide by the direct oxidation of ethylene is tered. The reaction shown Although the preparation of treated in a similar manner. The various methods of obabove has been suggested as c h l o r o h y d r i n has shifted taining ethylene glycol are reviewed and the hydration of a method of manufacturing from the p r o c e d u r e e m ethylene oxide is discussed at some length. A brief dethe ether (36) and has the ployed b y Wurtz t o a scription is also given of the preparation of ethylene glycol merit t h a t similar hypochlomodification of that disby a process starting with formaldehyde and carbon monrites are known t o form; as a covered b y Carius in 1863 oxide. The reactivity of ethylene oxide is illustrated with matter of fact, some of them, (4) in which hypochlorous a variety of chemical reactions, and various uses are mensuch as tert-butyl hypochlotioned. The preparation of two of the more important acid was allowed to react rite, are stable and can be with ethylene, and ethylene classes of derivatives-glycol ethers and ethanolaminesused t o form chlorohydrins is presented in more detail. glycol has become a n end with the corresponding ethers product rather than a startas by-products. Irwin and ing material as in Wurtz's Hennion (26) have also done time, a great chemical industry has been founded on these two work along this line, but there seems t o be no clear-cut proof early reactions. as to the mechanism of the reaction. Finally, higher chlorination products of ethane have been found in small quantiPREPARATION OF ETHYLENE CHLOROHYDRIN ties, and can best be explained as the products of direct chlorinaThe general reactions involved in the preparation of chlorotion of ethylene dichloride. Means to avoid the formation of hydrin are shown by the equations: these undesired by-products have been the subject of many Cl? HZO .--) HOCl HCl patents throughout the past 40 years. Most of them were based CHz=CH, HOCl --f ClCHzCHZOH on the presumption that if the chlorine could be dissolved in the water and the reaction allowed to proceed t o the complete formaBy passing chlorine into water, a solution of hypochlorous acid tion of hypochlorous acid, little or no by-product would be is formed. This hypochlorous acid then reacts with ethylene, formed. There is some doubt as to the validity of this assumption. bubbled thiaugh the solution, t o form ethylene chlorohydrin. A While there are, of course, other methods of preparing ethylene similar reaction can be written for other olefins, but ethylene and chlorohydrin which are of purely theoretical interest, the most propylene seem to be the only two that react a t all well in this usual procedure is to pass chlorine and ethylene into water simulsort of system. Indeed, the German chemists reported that even taneously. propylene reacted so poorly as to give an over-all 50% yield of A very satisfactory method for carrying out the chlorohydrin propylene oxide, compared to their 75y0yield of ethylene oxide. procedure commercially was the one used in Germany (15). The following equations show some of the by-products accompanying the reactions: A tower lined with acidproof brick was fitted at the bottom CIS CHz=CH2 +ClCHzCHzCl with suitable nozzles for the introduction of ethylene and chlorine ClCHzCHlCI Clz +ClCHaCHClz HCI gas as well as water. The towers were about 50 b y 5 feet. The unreacted gases passed from the top of the tower into a scrubbing ICICHzCHzOH HzO C1z ---t CICHzCHzOCl HCI HzO tower through which caustic was pumped. This knocked out I ClCHzCHzOCl CICHPCH20H + nearly all of the ethylene dichloride in the off-gas, and any acidic CICH&H2-O-CHZCHZCI HOCl materials as well. The scrubbed gases were partly recycled and As might be expected, if hypochlorous acid is in equilibrium partly vented. The amount recycled was such that with a 9570 ethylene purity, the gas to the chlorohydrinators was about 70% with chlorine and water, some free chlorine will be available to ethylene. A concentration of about 4.570 chlorohydrin was react with ethylene to form ethylene dichloride. This is espemaintained in the solution, and the operating temperature a t the cially true, if, instead of preparing a hypochlorous acid solution top nf the tower ran about 50' C. separately, and then reacting it with ethylene, the chlorine and As might be expected, the purity of the gas exerts a marked ethylene are introduced simultaneously into the same reactor, but effect on the capacity of the tower to allow complete reaction with through separate diffusers. There is then opportunity for the the chlorine. Results obtained in a small experimental column chlorine in solution to react with the ethylene, and for gaseous operated countercurrently have shown that with a constant level chlorine to react with the hydrocarbon. At any rate, considerof foam the capacity is about proportional to the purity of the gas. able quantities of dichloride are obtained in the reaction, and the The concentration of ethylene chlorohydrin in the liquor exerts problem is discussed more in detail below. a powerful effect on the amount of chlorinated by-produrts The formation of another by-product, dichloroethyl ether, could
E
+
+
++
+
+
+
+
+ +
+ +
2402
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
December 19%
formed in the reaction. The results of some work carried out in the pilot plant have shown that an increase in the chlorohydrin content of the solution is accompanied by a n increase in the relative quantity of dichloride formed. This bears out the general conclusions reached by Gomberg (18),who also points out the effect, of many dissolved salts and acids.
2403
along with the oxide and some water. Because the dichloride forms an azeotrope with water, the difficulty 'of separating it from the oxide is increased. I n addition t o this, if one wishes to obtain an oxide relatively free of acetaldehyde from this process, a more elaborate distillation procedure must be employed.
PREPARATION OF ETHYLENE OXIDE
The preparation of ethylene oxide from ethylene chlorohydrin is a reaction so well documented in the literature t h a t i t should suffice t o show the generalized reavtion. HOCH&H&l
+ MOH +CHS-CI-TZ + MC1 + H2O
From a theoretical standpoint, any fairly strong base will cause saponification of the chlorohydrin, although one would not ordinarily consider the use of amines, because they would tend to react to form more-substituted amines. The utility of any base in this reaction is dependent on the by-products it: tends t o form in the reaction; the two predominating ones are:
+
It is seen that some acetaldehyde is formed, as well as some ethylene glycol. It is reported (I?') t h a t magnesium oxide tends to favor the formation of acetaldehyde; whereas the use of sodium, and presumably potassium, hydroxide causes the undue formation of glycol. Ethylene oxide is readily converted to acetaldehyde over certain catalysts a t elevated temperatures; and it is problematical whether the glycol is formed by direct hydrolysis of the chlorohydrin or whether some oxide is hydrated immediately after formation. Both problems might well be the subject for academic research. The common commercial procedure for carrying out the reaction is to mix the chlorohydrin solution with calcium hydroxide (24.4)and heat it to bring about the reaction, and either simultaneously or subsequently t o drive out the ethylene oxide, which is then condensed and further purified by distillation. A number of patents cover details of the operations and one might, by picking out the salient features of many of them in addition t o open art, arrive a t a sort of idealized saponifier system. I n this system the chlorohydrin solution, a t a concentration of 6 t o S'%, is mixed with lime slurry of 10 to 15% calcium oxide concentration and heated for a few minutes t o promote the reaction (3). The reacted mixture is then fed t o a fractionator a t some distance above the mid-point. Open steam is fed t o the bottom of the fractionator, because some sort of vigorous agitation is needed t o keep the lime in suspension. Somewhere near the top of the column a small stream of caustic solution or lime slurry might be added to effect saponification of any unreacted chlorohydrin t h a t would tend t o come over with the crude oxide (19).
*
90 80--
6
70--
5
60.--
.
so-0
+ MCI
0 ''
I
8E 0
'0'
HOCHzCH2Cl MOH +HOCHzCHzOH CH~-CHQ 4CH&HO
*
The reaction of chlorohydrin with a n inorganic base is extremely rapid, so.much so in fact, t h a t a rather rough attempt t o determine its velocity with lime led t o the untenable conclusion that it was a unimolecular reaction. Tho limiting factor was the rate of solution of the lime in the slurry. A corresponding attempt with sodium hydroxide showed the reaction t o be too rapid.to measure conveniently with the available equipment. Superficially one might conclude from the vapor-liquid equilibrium curve shown in Figure 1 t h a t the purification of ethylene oxide from its aqueous solution would be relatively simple. However, reports on the work at Zweckel, Gendorf, and Ludwigshafen indicate the use of multiple towers with as many as fifty plates each (16). The reason for this is that the ethyle~iedichloride present in the chlorohydrin solution to a greater or lesser extent has carried right
I
I
10
20
l l 40 50 ETHYLENE OXIDE IN LIQUID, MOLE
Figure 1.
1
I 30
96
Vapor-Liquid Equilibrium Curve for Ethylene O x i d e w a t e r
Another widely and more recently employed process for the manufacture of ethylene oxide is the direct oxidation of ethylene in the presence of a catalyst. This process seems to have stemmed in part from the investigations of Lenher (SI),who discovered that in the nonexplosive oxidation of ethylene in open tubes, the two principal reactions were the formation of ethylene oxide and formaldehyde. Shortly after this work appeared, a series of patents based on the work of Lefort (SO) began t o issue, which demonstrated the ability of a silver catalyst, among others, t o bring about the oxidation of ethylene to ethylene oxide. Since that time a considerable amount of literature has developed covering the preparation of suitable catalysts and supports; the recovery of the product from the reactor effluent, a problem presenting certain engineering difficulties; and stcudips of the tnechanism of the reactions occurring in the ronverter.
To summarize the process briefly: A mixture of ethylene and air, the latter in considerable excess, is passed through a tube containing a silver catalyst which is frequently de osited on a support, and the reactor temperature is maintainel somewhere between 200' and 350' C., depending on the catalyst. The effluent gases contain nitrogen, oxygen, unreacted ethylene, carbon dioxide, and ethylene oxide. The concentration of the latter may be as low as 1% and as high as 4 to 5%. A recent paper (33) by McBee, Hass, and Wiseman gives about the only published data of actual experimental results on this type of preparation. Using a silver catalyst laid down on a corundum support in a borosilicate glass tube, they found t h a t the most favorable conditions for the reaction were a contact time of about 1 second a t a temperature of 268' C., when a fresh catalyst was employed; and 280' C. for a catalyst a month old. A ratio of air t o ethylene of 17.5 t o 1 gave a conversion of 3Oy0,and a yield of 45%. The most extensive study of the reaction which has been published is the series of articles by Twigg (S9),in which the merhanism of the whole reaction was thoroughly investigated from the standpoint of both a flowing system and a static system; in addition, the reaction of ethylene on chemisorbed oxygen monolayers was studied.
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
2404
Although there is no information available on the design of plants using this process in the United States, the salient features of the design of a plant that was to have been operated by I. G. Farbenindustrie A.-G. have been published (40). A good idea of the equipment involved is given. A reactor containing 3055 tubes, each 25 to 32 cm. in diameter and 3.35 ineters long, was projected. Each tube had a volume of about I .65 liters, and i t was intended that it should hold about 1 liter of catalyst. There were to be two pairs of these converters, one pair cooled by circulating oil, the other by a water-steam system. It was intended to evaluate the difference between the two modes of' cooling. The expected material balance of the plant is as follows: Material Balance 85.2
+ 69
Vol. 42, No. 12
Glycolic acid has been prepared by a continuous process wherein a solvent mixture, containing on a niolal basis 2 parts of glycolic acid, 1 part of water, and approximately 0.02 part of sulfurid acid, is used to absorb, in a gas scrubber, 1 part of formaldehyde and 1 part of water. The resulting solution now containing glycolic acid, formaldehyde, water, and a catalyst in the ratio of approximately 2:1:2:0.02 is passed through a convcwion chamber which is filled with glass heads wherein it contacts carbon monoxide, the reactants being maintained in this chamher a t a temperature of approximately 200" C. and a pressure of approximately 700 atmospheres. The formaldehyde is , substant,ially quantitatively converted to give a product discharged from the converter having sul)stantially the composition, 3 parts of glycolic acid, 1 part of water, and 0.02 part of sulfuric acid. One part of glycolic acid is removod by crystallization or dist$illation, and the residue containing glj.c.olic acid, water, and sulfuric acid in the ratio of 2:1:0.02 returned to the scrubber to :it)sorb more formaldehyde and water.
Feed, 20' C. =
154.2 CU. meters/hour CnH4 1750 cu. meters/hour air 1750 cu. meters/hour recycle gas
Effluent 70' C., cu. meters/hour Total 3500 Oxide 77 Con 126 HzO 126 C ~ H I 31.5
20° C., cu. m e t e r d h o u r 2990 66 108 108 27
It was reported that the original intention was to adsorb the oxide on charcoal and desorb it with steam. However, it was discovered that only about 50% of the adsorbed oxide could be recovered, the remainder apparently polymerizing. Absorption in dilute acidic glycol to form more glycol was finally decided upon. ETHYLENE GLYCOL
The hydrogenation of the glycolic: acid may then be carrjed out subst,antially as described in another pat,ent (32). This patvnt describes the hydrogenation of ethJ.1 arid isobutyl glycolate, but) also points out that a glycolic: anhytiritic, which is essentiall?. a polyglycolide, dissolved in an iilvoholic solvent such as isot)ut).l alcohol or, more particularly, ethylrncl glycol could be hydrogenated in better than 95oj, yields at n tpmperature between l M o and 216" C. at hydrogen pressures of : h u t 900 atmospheres. Probably by far the greatest quantity of glycol produccvl i n this country is made by the hydration of ethylene oxide. The reactions involved, including those yielding the major by-products, are as follows: CHz-CHz
+ H z 0 HzSOa --+ HOCHzCH20H
'0'
Ethylene glycol can be prepared by any of a number of reactions. The reaction of ethylene chlorohydrin with caustic gives rise to this compound according to the equation:
+ MOH --+-HOCHzCHzOH + MC1
HOCHzCHzCl
hnother procedure is to hydrolyze ethylene dic-hloride with a base :
+ 2NaOH -+ HOCHzCH20H + 2NaCI + NaOH +CHz=CHCI + H20 + NaCl
CICH&HzC1 CICH&HfC1
At the same time an accompanying reaction yields vinyl chloride. However, it has been shown ( 2 1 ) that if, instead of a strong base, a weaker one such as sodium carbonate is used, the unwanted by-product is minimized. The method suffers from the fact that sodium chloride must be separated from the finished product, and this would have to he done during the evaporation stage with a salt box. A two-stage process apparently employed by one of the major producers in this country is described in the patent literature (29, 32).
0
/I
C
/ \
CH2 0
1
1
0
+ Hf ROH -+ 2H0CH2CHz0H
CHz
C ''
/I 0 The first step involves reaction of formaldehyde with carbon monoxide under relatively high pressure in the presence of an inorganic acid catalyst, using an organic acid as a solvent. AIthough the exact conditions under which this process is carried out have not been published, the following quotation from one of the patent examples (299)will give a rough idea of what is required.
As in the preparation of the oxide itself, the reactions are old (41), but there is a considerable patent literature describing particular methods of carrying out the hydration. I n general, the oxide is mixed with water containing a small amount of an acid, and the solution is heated to promote the reaction. After the reaction has been completed, the acid catalyst, usually sulfuik acid, must be neutralized with a base or removed with an ionexchange resin. The solution is then evaporafed to remove water and the final product is distilled. The reaction itself is somewhat exothermic, and a nice balance must be attained to keep the reaction within bounds, especially if it is carried out as a batch proredure. If cold water is used as make-up in a continuous system, the heat of reaction is just about,enough to keep the reaction going if the solution is fairly dilute. It seems to be common to employ a 10 to 20% solution of oxide in water for this reaction to minimize the formation of polyglycols. A series of curves reported 1)y Matignon et al. (34)demonstrates the effect of oxide concentration on the format,ion of these by-products. This is shown in Figure 2. Because di- and triethyleneglycol are much less in demand than the mono compound, a nice economic balance must be made to determine exactly a t what concentration to operate a plant. The neutralized or deionized solution is then evaporated in suitable multieffect evaporators, and finally distilled under vacuum to give a specification product. The concomitant, diand triethyleneglycols may be separately fractionated from the bottoms of the glycol fractionator, or as side streams from the tower, depending on the specifications to be met.
INDUSTRIAL AND ENGINEERING CHEMISTRY
December 1950
ETHYLENE OXIDE USES
The genius of ethylene oxide as a chemical intermediate is its ability to react with what are known as “active hydrogens,” the hydrogen bound to oxygen, nitrogen, sulfur, and the like, to form compounds with a “hydroxyethyl” group attached. Furthermore, because the resulting compound has a new “active hydrogen” more oxide can react, and thus a number of ethoxy groups can be added to a molecule. As these groups impart a high degree of water solubility to whatever they are attached to, it naturally follows that ethylene oxide has become of considerable use in the manufacture of surface-active agents. Reactions of Ethylene Oxide. The following examples may serve to show the scope of reactions into which ethylene oxide enters. The first reaction is that with an alcohol. If 1mole of oxide is added to 1 mole of alcohol, the simple ethylene glycol monoalkyl ether is formed (7, 83). ROH
+ CH2-CHz
----t
R-O-CH&HsOH
‘O/ R-0-CHzCHzOH
2405
might a t first seem. The resulting products are excellent intermediates for the preparation of detergent8 and other surface-active agents. The reaction with carboxylic acids in the preparation of surface-active agents is well known. I n a similar manner, ethylene oxide will react with the hydroxyl hydrogen in phenol (25).
6
0-( C H ~ C K ~ O ) ~ - I - C H ~ C H ~ O H
+ n-CTZCH,
----+
0
While there is little apparent use a t present for such a reaction with ordinary phenol, its use with the alkylated phenols is of considerable interest. Valuable surface-active agents are now on the market in which phenol alkylated with a long-chain hydrocarbon, say an octene or nonene, has been treated with ethylene oxide until the right degree of solubility has been attained. These nonionic agents are becoming more and more useful as time goes on, because they are not affected by the presence in water of salts that might decrease their activity.
+ CHz-CHz * \O’
R-O-CHZCHA-CH~CH~OH
However, the oxide has a strong tendency to react with the resulting compound, so that in order to obtain a major yield of the simple ether, it is necessary to employ a large excess of the alcohol. I n Germany (2) it was customary to use about 5 parts by weight of .the alcohol to 1 of the oxide. The reaction was carried out under a pressure of about 750 pounds per square inch gage a t temperatures as high as 220 O C. Under these conditions and with methanol as the alcohol, a holding time of about an hour was used. With other alcohols, the pressures and times were somewhat different. Even with the excess alcohol, an appreciable quantity of the ether of diethylene glycol is obtained; and if the ratio of alcohol to oxide is lowered, more and more of the di- and higher derivatives is obtained. The reaction can be carried out effectively without a catalyst, but the addition of a small amount of acid or base increases the rate so that the temperatures and pressures need not be so high. On the other hand, the use of a catalyst complicates the picture, in that the catalyst should be neutralized before the product is distilled; and this presents some equipment difficulties, which though minor may outweigh the cost of heavier equipment required for noncatalytic operation. If, instead of a large excess of alcohol, a small quantity of diethylene glyc.01 is used and oxide is introduced under mild conditions of pressure and temperature, over a long period, it is possible to obtain waxes of varying melting points. Thus the German industry (2) started with 110 kg. of diethylene glycol, and added 2600 kg. of oxide a t a temperature of about 130” C. and a pressure of about 1.5 atmospheres. The oxide was added a t a rate of about 100 liters per hour and a wax melting a t about 45” C. was obtained. If a heel of wax was used as a starting material and a catalyst of sodium methylate was employed, a wax of high molecular weight, about 4000, was obtained. It required about 50 hours to make 5000 pounds, starting with about 600 pounds of heel. Long-chain al,cohols can be employed instead of the shorter chains, hut one is faced here with something of a dilemma. I t would be impracticable to use a large excess of alcohol in order to obtain the addition of a single mole of oxide. The result would be a mixture of unreacted alcohol with others containing several moles of oxide. However, if one wishes t o effect complete solubilization of the alcohol in water, it is necessary to add several moles of oxide to the alcohol, say about eight or nine as a minimum for dodecanol (6). Thus the problem is not so serious as it
MOLES WAT€R/MOLES OXIDE
Figure 2.
Conversion of Ethylene Oxide to Mono- a n d Polyglycols
Another reaction to produce similar products is with the longchain mercaptans to produce another series of nonionic wetting and surface-active agents (9). R-SH
+ ~ ~ H z - C H ~ R-S-(
CH2CHzO)n-I-CH&H20H
\O/ The hydrogens on ammonia and the amines are also reactive to ethylene oxide. The simplest case is the reaction of oxide with ammonia to yield ethanolamines. NHI
+ CH2-CHz
+NHzCHzCHzOH
\O/ NHI
+ 2CH2-CH2-+NH< ‘O/
CHpCHzOH CHzCHzOH
Here, again, is the possibility of obtaining a series of products, depending on the relative amounts of amnionia and oxide present. I n order to obtain predominantly the mono- compound it is necessary to use a large excess of ammonia (27). As less ammonia is used, the di- and tri- compounds increase in yield and higher polymers are obtained (37). The reaction is exothermic and must be carried out in equipment that is capable of removing
INDUSTRIAL AND ENGINEERING CHEMISTRY
2406
considerable quantities of heat. An interesting sidelight on the reaction has been brought out b y Ferrero et al. (11). It is obvious that if one were to recycle the mono- compound, more di- and tri- would be formed at the expense of the mono- compound. These authors state that by the addition of diethanolamine t o the reaction, the further formation of the di- compound seems to be suppressed. Thus primarily mono- and triethanolamine can be obtained by recycling the diethanolamine in the reaction. The authors emphasize that this appears to be a true repression rather than, as one might expect, the recycled material merely going to the next higher in the series-Le., triethanolamine. Most amines seem to react with ethylene oxide without requiring drastic conditions; the aliphatic amines are said to react somewhat more easily than the aromatics owing to a greater basicity (14). An interesting reaction with amines is t h e formation of choline salts (28).
CH3
CHs
\
CHs-N-HCl
/
+ CHZ-CHs \O/
CH3
\+
+ CHa-N-CH2CH*OH---CI /
-
CH3
Another reaction of considerable importance is with hydrocyanic acid t o form ethylene cyanohydrin ( 5 ) . HCN
+ CHs-CHs
+HOCHzCHzCN
‘O/ Because the product is the precursor of a number of commercially important materials, a good deal of study has been devoted to its preparation and there is a considerable patent literature covering it. The reaction may be carried out either with the anhydrous acid, or with a solution of one of its alkali salts; and t h e yields in either case are fairly high. The resulting cyanohydrin can b e dehydrated t o make acrylonitrile (8), or otherwise reacted t o make acrylic acid esters which are valuable monomers in the plastic trade (38). Another reaction, perhaps less well known, is the alkylation of benzene with ethylene oxide in the presence of aluminum chloride to yield phenyl ethyl alcohol (sa). It is also stated that even the paraffin hydrocarbons will undergo this reaction.
a+
CH2-CH2
‘O/
0-
+
CHsCHIOH
Perhaps one of the best-remembered reactions is that of ethylene oxide with a Grignard reagent t o give an alcohol with two more carbon atoms ( d o ) , thus giving a method which both produces a n alcohol and lengthens a carbon chain.
Vol. 42, No. 12
With mercaptans, the corresponding hydroxyethyl sulfide is obtained. When a concentrated solution of sodium bisulfite is treated with the oxide, sodium p-hydroxyethane sulfonate or sodium isoethionate is formed ( I O ) . NaHS03
+ CH2-CH2 +HOCH&H&303Na \O/
I n considering the properties of ethylene oxide, one should not overlook two papers ( l a , I S ) , which showed that at relatively high temperatures (ca. 400” C.) ethylene oxide was a prolific source of free radicals, and was found to catalyze the decomposition of such compounds as ether and acetaldehyde materially. It had a powerful effect on the thermal polymerization of ethylene, increasing the polymerization rate as much as twentyfold. Another use of oxide, not strictly chemical, for which there is a large bulk of literature, is in the field of pesticides; indeed, a host of writers have described its use both alone and in conjunction with other compounds such as carbon dioxide and ethylene dichloride, for pests ranging from the confused flour beetle to gooseberry bushes. It has found a wide use in the field of grain fumigants. Another interesting use has been reported b y Ziese (@), who described a procedure for producing sols and gels of some of the metal oxide hydrates. The halides of aluminum, chromium, iron, and zinc were allowed t o react slowly in solution with the oxide; it was found that if not more than about 90% of the metal halide was allowed t o react, sols were formed which could be dried and then redissolved in water, alcohol, or glycerol. If less than 5y0 of the original halide remained unconverted, the sol was unstable and the material gelled. Finally, if an excess of oxide were used, after some hours gels were formed that showed the phenomena of humming, syneresis, and dehydration. CONCLUSIONS
It will be evident from the foregoing reactions, merely a sampling of a voluminous literature on the subject, that ethylene oxide is an organic intermediate of vast potentialities in the chemical industry. As may be imagined, the greatest use of ethylene glycol is in the field of permanent-type antifreeze. It ha? been estimated that as much as 7570 of the total production in the United States has entered this market. Another important usage is in the preparation of resins of the dibasic acid-glycol type such as, for instance, the products stemming from phthalic anhydride. Although these resins have been available for some years, a new product of similar nature based on terephthalic acid has made its appearance as a fiber, and may be expected to increase materially the use of ethylene glycol in the chemical industry. ACKNOWLEDGMENT
‘R-CHzCH20H .4n examination of the l i t e r a h e indicates that, although this may be a reaction of preparative interest, yields are frequently poor and often unanticipated products are obtained. Ethylene oxide and other oxides are reported to react with both phosphoric and phosphorous acids t o form polyglycol esters of various sorts, d a e n d i n g upon the quantity of oxide employed ( 1 ) . The reaction is very similar to that with carboxylic acids, as might be expected. With hydrogen sulfide, when passed over a n appropriate catalyst in the vapor state, ethylene oxide yields thiodiglycol in 90% yields or better (35).
H2S
+ 2CHz-CH2 ‘0’
HOCH&H*--S-CHZCH~OH
The author is deeply indebted to L h s . B. S. Kolmes for her assistance in preparing this paper for publication. LITERATURE CITED
(1) Adams, C. E., and Shoemaker, B. H. (to Standard Oil Co. of Indiana), U. S. Patent 2,372,244 (March 27, 1945). (2) Brandner, J . D., and Goepp, R. M., Jr., “hlanufacture of Ethylene Glycol, Polyglycols, Glycol Ethers, Ethylene Cyanhydrin, and Acrylonitriie, Phenyl Ethyl Alcohol and Related Derivatives of Ethylene Oxide in Germany,”*U. S. Dept. Commerce, Office of Technical Services, FIAT F i n d Rept. 1311. (3) Britton, E. C., Nutting, H. S., and Petrie. P. S. (to D o w Cherriiea1 Co.), U. S. Patent 1,996,638 (April 2, 1935). (4) Carius, L., Ann., 126, 195-217 (1863). (5) Carpenter, E. L. (to American Cyanamid Co.), U . F. Patelit
2,453,062 (June 4, 1946).
December 1950
INDUSTRIAL AND ENGINEERING CHEMISTRY
(6) Cohen, M., Compt. rend., 226,1366-8 (1948). (7) Cretcher, L. H., and Pittenger, W. H., J . Am. Chem. SOC.,46, 1503-4 (1924). (8) Davis, H. S.,and Carpenter, E. L. (to American Cyaqamid Co.), U. S. Patent 2,452,554 (Nov. 2,1948). (9) Davison, J. B., and O h , J. F. (to Sharples Chemicals, Inc:), Ibid., 2,494,610 (Jan. 17, 1950). (10) Erlenmeyer, E., and Darmatiidter, L., 2. Chem., 4, 342-3 (18fiS). (11) Fe&&’.P:, Berbe, F . , and Flamme, L. R., Bull. SOC. chim. Belges, 56, 349-68 (1947). (12) Fletcher, C. J. M., J . Am. Chem. SOC.,58,534--5 (1936). (13) Fletcher, C. J. M., and Rollefson, G. K., Ibid., 58, 2135-40 11938). (14) Gabel, G., Bull. SOC. chim. France, 41, 936-40 (1927). (15) Goepp, R. M., Jr., Fuller, D. L., Vaughan, W. E., a’nd Brandner, J. D., “Manufacture of Ethylene Oxide via Chlorohydrination of Ethylene,“ M A T Final Rept. 874,7 (1947). (16) Ibid., p. 12. (17) Ibid., p, 19. (18) Gomberg, M., J. Am. Chem. Soc., 41, 1414-31 (1919). (19) Green, A. D., and Waterman, W. W. (toStandard dil Development Co.), U. s. Patent 2,232,910 (Feb. 25, 1941). (20) Grignard, V., Bull. SOC. chim. France (3), 29,944-8 (1903). (21) Hibbert, H., U. S. Patent 1,270,759 (June 25, 1918). (22) Hopff, H. (to I. G. Farbenindustrie A.-G.), Ibid., 2,029,618 (Feb. 4, 1936). (23) I. G. Farbenindustrie A.-G., Brit. Patent 271,169 (Feb. 22, 1926). (24) Ibid., 292,066 (June 11,1927). (25) I. G. Farbenindustrie A.-G., French Addition Patent 39,773 (Feb. 17, 1931). (26) Irwin, C. F., and Hennion, G. F., J . Am. Chem. Soc., 63,858-60 (1941).
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(27) Kautter, C. T. (to Shell Development Co.), U. S. Patent 2,051,486 (Aug. 18,1936). (28) Kihner, F.. French Patent 763,107 (April 29, 1932). (29) Larson, A. T. (to E. I. du Pont de Nemoura & Co.), U. 5. Patent 2,153,064 (April 4,1939). (30) Lefort, T. E. (to SociBt6 franpaise de catalyse gBn6rali&e), I W . ,1,998,878 (April 23,1935). (31) Lenher, S.,J . A m . Chem. Soc., 53,2420-1 (1931). (32) Loder, D. J. (to E. I. du Pont de Nemours & Co.), U. 5. Patent 2.285.448 (June 9.1942). (33) MoBee, E. T., Ha& H.‘B., and Wiseman, P. A., I N ~ .E N ~ . CHEM.,37,432-8 (1945). (34) Matianon. C.. Moureu, H.. and Dode, M., Bull. 8oc. d i m . France (5), 1,1308-17 (1934). (35) Nenitzescu, C. D., and Scarlatescu, N., Ber., 68B, 587-91 (1935). (36) Perkins, G. A. (to Union Carbide and Carbon Corp.), U.5. Patent 2,042,862 (June 2,1936). (37) Reid, E. W., and Lewis, D. C. (to Carbide & Carbon Chemicals Corp.), Ibid., 1,904,013 (April 18,1933). (38) Rohm & Haas A.-G., French Patent 675,327 (May 17,’1929). (39) Twigg, G. H., Proc. Roy. Soc. (London), A188, 92-104, 105-22. 123-41 (1946). (40) Vaunhan. W. E.. .and Goem. R. M.. Jr.. “ProDosed Ethylene Oxide ’Manufacture via-Oxidation of Ethylene at Zwmkel near Gladbeck” FIAT Final Repl. 875 (1947). (41) Wurtz, A., Ann., 113,255-6 (1860). (42) Wurtz, A., Compt. rend., 48,101-4 (1859). (43) Ziese, W., Ber., 66B, 1965-72 (1933). 1 - - - 1 - - -
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R E C E I V ~April D 21, 1950.
Presented before the Divisions of Petroleum Chemistry and Gas and Fuel Chemistry, Symposium on Chemicals from, Petroleum, at the 117th Meeting of the A M ~ R I C ACNH E M I C AS~o c m w , Houston,Tex.
Utilization o f Butyl Rubber i n A u t o m o t i v e Inner T u b e s D. J. BUCKLEY, E. T. MARSHALL, AND H. H. VICKERS Esso hboratories, Standard Oil Development Company, Elizabeth, N . J . T h e wartime shortage of natural rubber created a phenomenal demand for the new polymer, Butyl rubber, primarily for the manufacture of automotive inner tubes. Extremely difficult problems were encountered in fostering the use of Butyl. A major crisis occurred when inner tube fabricators attempted to make Butyl passenger tubes on equipment designed for natural rubber at far above prewar rates. As a result, an extensive use-development program was carried out. A study of the automatic butt splicing of inner tubes led to mechanical improvements which aided materially in offsetting the characteristically differ-
ent nature of Butyl. A large scale factory test program was run to correlate polymer plant variables with inner tube plant experience. The results demonstrated particularly the mnsitivity of Butyl tube fabrication operations to small variations in factory conditions. The severe 1%6-47 winter spotlighted the tendency of Butyl passenger tubes to “buckle” when in subzero seryice in the northern United States and Canada. Extensive laboratory studies and field trials eventually showed that this buckling tendency could be overcome by proper compounding and curing of the Butyl tubes.
Y T H E middle of 1949, the rubber industry of the United Sthtes had consumed over, 650,000,000pounds of Butyl
its use by the fabricator of the end products. I n the case of Butyl, such problems were greatly magnified because the development period was compressed abnormally under the influence of the tremendous war and postwar demand.. Three specific problems were encountered in the manufacture of Butyl inner tubes: difficulties in splicing the raw tubes, unexplainable variations in factory processing experience, and service failures of finished tubes in operation at subzero temperatures. A brief relation of the work t h a t was done in aiding in the solution of these three problems should be of value. Such experiences are felt t o be typical of the many predictable and unforeseen problems t h a t may be encountered in the development of any new raw material. The achievement of Buccess in the use of Butyl t o fabricate inner tubes of high quality can be credited primarily t o the rub-
rubber and had fabricated enough Butyl rubber inner tubes to equip completely over 50,000,000automotive vehicles. Yet Butyl was not invented until 1937 and was not commercially produced until March 1943. This phenomenal growth in the use of a new product is illustrated in Figure 1. The war, and the consequent shortage of natural rubber, provided the chief impetus for this great demand for synthetic polymers. Neoprene and Buna N, in commercial production in 1933 and 1941, respectively, reached high levels of use early in the war, but were then exceeded by Butyl as Butyl found i t P place in inner tube manufacture. No new material can be brought t o a high level of use without encountering many problems, not only in its manufacture but in
