I
Color Stabilization of Gasoline by Amines L. IT. SORG,Standard Oil Company (Indiana), Sugar Creek, 210.
T
HE color of a gasoline, and The normal aliphatic amines, u p to and inc r e a s e d , and gum formation, tvithitthecolorstabllity, eluding the amy/ amines, are shown to possess with loss of knock r a t i n g , i s has always been an imcolor-stabilizing properties. While the amino bprevented e a c c o m (13). p a n i e dThis b y may a n also imp o r t a n t factor from the sales v i e w p o i n t , While dyeing of group is probably responsible f o r the color-stabiprovement in color s t a b i l i t y , g a s o l i n e hab, in many cases, lizing action, its effectiveness is modijed by the a l t h o u g h it appears that the eliminated the close control over color-stabilizing results obtained length and number of alkyl groups attached. The amyl amines are the most effectiveof the various by i n h i b i t o r s a r e v a r i a b l e , color tliatwasfornierlyrequired, the problem has in no sense been depending both on the inhibitor amines examined, and of them the primary and entirely eliminated. Many of and the kind of g a s o l i n e inthe gasolines that are marketed secondary are best. volved. undyed are third grade and are Little additional improvement in color stnS u m e r o u s c h e m i c a l combility is to be gained during a one-hour exposure pounds have been proposed in often found to be rather colorunstable. Also, dyed gasolines in surllight in usingover 0.003 per cent by weight the literature as color stabilizers are be f o u n d t h a t become in gasoline, either with or witho f a given amine. The natural stability of the "off-shade" in the sunlight from out reference to gum-inhibiting gasoline being h a t e d does not greatly affect the the color instability of the gasoeffects. Among the earliest was line itself. amount of amine necessary to secure maximum anthracene which was proposed possible color improvement, but the magnitude by Bjerregaard (3). P h e n o l s In the past, initial color and of the maximum possible color improoement and cresols mere also mentioned. color s t a b i l i t y have been obtained by various m e t h o d s . ' While anthracene was for a time i.aries with it. T h e m o s t common of these used as a color stabilizer, it has methods has been the treatment The amyl amines pass lhrough the operation been superseded by effecwith s u l f u r i c a c i d followed of sweetening with plumbile and sulfur with no tive compounds. Egloff, loss in effectiveness toward sunlight color stabiliFaragher, and Morrell have proby neutralization a n d redisposed a variety of substances tillation to the desired boiling zation. (10, 11). Among the more succharacteristics. Brooks (4)has shown that complete neutralicessful were gum camphor, urea, zation of the oil after treatment with acid is very important pseudocumene, and several naphthalenes. Compounds similar in stabilizing the color. Traces of sulfuric acid or sulfur di- to acetanilide were suggested by Calcott and Lee ( 7 ) . aoxide will rapidly cause discoloration. The concentration Naphthol has been proposed, but it is probably more satisand quantity of acid, the temperature of treatment, and the factory as a gum inhibitor (15). Pyrogallol (2s) is in the time of contact have been the subject of much work. Usu- same category as a-naphthol. Brooks (5) suggested ammonia and its organic derivatives, ally, it is well to use acid of no greater concentration than is necessary to accomplish the desired results. The tempera- including primary, secondary, and tertiary amines, but amture should be kept relatively low (70" to 90" F. or 21.1" t o monia only was specified in his patent claims. Recently, 32.2"C.) in order not t o harm the color (W,20). The quantity Calcott and Lee (8) suggested a large group of amines and of acid t o be used varies with the type of stock and the de- have claimed aliphatic amines of four to eight carbon atoms, gree of treatment desired. Egloff and Morrell (12) studied such as the butyl and amyl amines studied in this work. It the factors affecting time of contact and concluded that the appears that these materials are specifically color stabilizers strength of the acid is a most important factor. and not antioxidants, and Rogers and Voorhees (22) have Another method that has come into increasing use during shown that various butyl amines and amyl amines may be the last decade is that of clay-treating (19, 24). This treat- used in connection with the inhibitor, B. A. P. (monobenzylment is carried out both in the liquid and vapor phases. p-aminophenol), to obtain an improved color stability. Since the amines have been shown to possess color-stabilizGoode (14) has shown the relationship between color, contact time, and yield. As the contact time decreases, both the ing properties, it seemed warranted to investigate the opticolor and yield fall off rapidly. Experience in this laboratory mum concentration and relative effectiveness of the various has shown that color stability falls off more rapidly as the compounds. yield from clay increases than does the initial color. The compounds so far investigated have been the normal In addition to the above major processes, there are numer- aliphatic amines from ethyl amine to amyl amine, with the ous other proposed methods such as treating gasoline vapors exception of propyl amine. The ethyl and butyl amines were with solid sodium hydr0xid.e (e),with solutions of zinc chlo- secured from the Eastman Kodak Company and were used ride (16,17)and various salts (9, d l ) , and with salts suspended without further treatment, The amyl amines were obtained from the Sharples Solvent Corporation as commercial prodon absorbent materials (18). To obtain color and color stability by these methods alone ucts. These were known to contain isomers but were used may be relatively expensive, and in many cases it may be un- as received, being representative of the type that would probdesirable to employ these treatments in obtaining the de- ably be available in large quantities. sired degree of color stability. The use of inhibitors is now a OF TEST METHODS well-recognized means of preventing deterioration of cracked gasolines; treating cost and losses incident t o treating are deThe tests of sunlight color stability were made by exposing the 1 A thorough discussion of the ohemical treatment of gaaoline IS to be found gaSOllne in French-type square quart (0.95-liter) bottles O n an ahmlnum painted board. The bottles (8 X 8 X 20 cm.) were in "Chemical Refining of Petroleum" by Kalichevsky and Stagner, Chemical carefully selected from the same lot so that the transmission of Catalog Company, New York, 1933.
''
156
February, 1935
157
I N DU STR I A L A N D E N G I N EE R I N G C H E M I ST R Y
radiant energy would be as uniform as possible. The bottles mere not vented during exposure, but the method of sampling (pouring) permitted air to enter the bottles at hourly intervals. They were filled t o the neck and stored in the cold until exposed. Immediately before exposure a 120-cc. sample was removed for t.he initial color determination. At hourly intervals a similar sample was removed from the same bottle. Thus, the same amount of gasoline was in each bottle during the entire period of test. To correct for variations in the intensity of the sunlight during the periods of exposure, the uranyl acetate-xalic acid actinometer was used as suggested by Beard and Reiff ( 1 ) . Twenty-five cubic centimeters of 0.1 IV oxalic acid solution containing 0.001 mole of uranyl acetate per liter were exposed with the gasoline samples in a separate 120-cc. oil sample bot,tle. .4t hourly intervals a new portion was exposed so that, after titration of the exposed samples with potassium permanganate, a record of the hourly sunlight intensit,y was obtained.
liter) bottle corresponds quite well with a n exposure of 4 hours in the glass bowl pump. A better correlation is obtained, however, by comparing the color after 1 hour in the quart bottle with a n 8-hour exposure in the pump. The halfhour and hour correlations do not correspond exactly because loss of color is not a linear function of the time of exposure. For practical purposes, 1 hour of sunlight test as here described is equivalent to 8 hours in the pump under the same sunlight conditions. OF QUARTBOTTLETESTING AND TABLE I. CORRELATION GLASSBOWL PUMP
COLOR AFTER QUART-BOTTLE TEST FOR:
INITIAL
COLOR 24 24 26
30min.
20+ 17 22
1 hr.
16 16
20+
2 hr. 16
16 17
3 hr. 15 16 17
COLOR AFTER GLASSBOWL TESTF O R : 4hr. 6hr. 8hr. 20 18 18 16
2 hr.
g?23
;A$
21+
21
20
Three dark aging tests were made. Each was a thermai test carried out under varied conditions. Storage at 51.6 C. (125” F.) for 12 weeks was in 120-cc. oil sample bottles with air present but not vented. The steam heat test involved heating 100 cc. of sample in a steam bath for 16 hours; the bottles were vented during the first half-hour but were tightly stoppered during the remainder of the test. In the bomb heat test, the temI I perature and time of heating were the same as in the previous test but no venting of vapors occurred, as the sample and bottle M/LLIC#AMS W O * r l L I C ACID D E C W P O S ~ O were tightly sealed in a steel bomb. FIGURE1. CURVEFOR CORRECTING THE VARIATIOV IN SUNAll colors were measured on a modified Saybolt chromometer LIGHT INTENSITY using artificial light. The modification consisted of enclosing the tubes in a wooden box that was painted black for maximum As shown in Figure 1,plotting the amount of oxalic acid de- absorption. This enclosure protected the tubes from incident composed for a time interval as a function of the Saybolt light and this eliminated errors that might arise frcm it. color after the same time interval, gives a valid relationship. SUNLIGHT COLORSTABILITY This particular curve was obtained on a blended dock that had been sweetened with plumbite and sulfur. This sample To evaluate the amines properly as sunlight color stabiwas quite color-stable, making it suitable for the purpose a t lizers, it is necessary to determine the optimum concentration hand, as it was desired t,o expose a portion of the same sample so that each amine could be studied under the most effective a t a varied sunlight condition over a period of a month. The conditions. The variables that would affect the optimum data seem to show conclusively that the color decreases as more oxalic acid is decompoqed. Also, the validity is supported by the fact that the point5 lie close to the curve. The averase deviation is less than half a unit on the Saybolt color scale. This curve applies only to the particular gasoline exposed and will differ in character with other gasolines. The exposure of many actinometer samples has shown that for brilliant summer sunlight about 30.0 mg. of oxalic acid are decomposed per hour. The experimental procedure was the same as related above. Several samples a week were exposed from June 1 to October 1, 1932. Usually the exposure was from 1O:OO A . ai. to 2:OO P. >I., a new sample being put out after each hourly interval. The average of about, two hundred hourly exposures is a decomposition of 31.08 rng. For convenience 30.0 mg. were suggested. This figure has been adopted as the “standard sunlight hour” for all of the hours of sunlight exposure mentioned here. 2 1 1 1 1 1 1 From a curve for the gasoline exposed, similar to Figure 1, we can readily determine what the Saybolt color would have 0 I l l O / C 0 4 5 6 7 ~ ) 8 been had the samples of gasoline received radiant energy WCICHT PERCENT of AMINC x id equivalent to that of the standard sunlight hour. iissuming FIGURE2. OPTIMUM CONCENTRATION CURVES Figure 1 to fit the case, it is necessary only to read the color FOR Two AMINES at 30,60, and 90 mg. of oxalic acid decomposed to convert the original colors to a standard sunlight basis of 1 , 2 , and 3 hours. concentration for a given amine are the type and natural The use of this device makes it possible to compare color color stability of the stock. I n determining the optimum stability data on a n equal sunlight intensity basis although concentration for n-butyl and n-amyl amines, two stocks, a the actual conditions of exposure may have differed somewhat straight-run and a blended (straight-run and cracked) gasofrom the standard. line mere used. The physical characteristics of the stocks A correlation between the color deterioration during one are given in Table 11. All stocks were from Midcontinent hour of exposure as shown above and that occurring in the crude, and these data are representative of those that were glass bowl of a gasoline pump for the same period of time and used for this work. Among individual samples there was a sunlight conditions was made. From such a correlation it is variation in color stability but all were plant products. The possible to convert laboratory exposure data to a practical amines were used in both a “moderately stable” and a “very basis (Table I). The half-hour interval in the quart (0.95- unstable” stock in order to show the effect of thiq variable.
I l l 1
INDUSTRIAL A N D ENGINEERING CHEMISTRY
158
A typically "very unstable" stock would decrease from eight to ten Saybolt numbers during an hour of sunlight exposure. Similarly, a "moderately stable" stock would lose about half as much. TABLE11. PROPERTIES OF GASOLINES STRAIGHT-
RUN
S
gr 1 5 5 / 1 5 5 OX. P.'I. Initial color A. S. T. M. 100-cc. distn.: Initial b j~ O C. ( O F.) % ' at 7 6 6. 158' F ) 105' C. 1221: F:) 14OOC. 284 F.) 200' C. 1392O F.) End point, a C. ( " F.) Doctor test
0.7132 66.9 30
&avii>,
40 (104) 18.0 60.5 90.5 171 '(340) Sweet
CRACKED BLENDED 0.7405 0.7260 59.6 63.4 30 30
40 (104) 13.0 36.0 64.0 98.0 204 (400) Sweet
38 (100) 14.0 42.0 77.0 191 '(376) Sweet
Figure 2 gives the curves of optimum concentration. The ordinate indicates the improvement in color stability during 1 hour of sunlight exposure measured in units of difference between the Saybolt color of the control and the gasoline containing the amines. The abscissas are the weight per cent of amine present. A small amount of improvement is to be observed with as small a concentration as 0.00075 per cent. However, for the butyl amine a maximum color improvement is obtained with about 0.002 per cent of the amine, regardless of the original color stability of the gasoline. An amount equivalent to 0.002 to 0.003 per cent is the optimum for the amyl amine. The data also show that for 1 hour of sunlight exposure the use of amines in concentrations above 0.003 per cent does not give additional improvement in color stability. The optimum concentration of amine is about the same for either butyl or amyl amine; however, the maximum improve ment in sunlight color stability obtainable is a function of the original color stability of the gasoline although this does not affect the optimum concentration of amine greatly. Fortunately, the greatest possible improvement in color stability is obtained on those stocks having the poorest original color stability. This is the condition in which the amines are most needed and are of the greatest use. I
I
I
I
1
\
14-
10
I
Vol. 27, No. 2
are given in Figure 3. A definite stabilizing action is exhibited by all of the amines throughout the whole period of exposure. It is clearly brought out that the alkyl amines are more effective as the number of carbon atoms in the alkyl group increases. These data do not, however, show a quantitative linear relationship between the length of the substituting group and the stabilizer effectiveness. In addition to showing the above relationship, data have been obtained t o demonstrate (Figure 4) that the effectiveness decreases from primary, t o secondary, to tertiary amine, though not linearly. The amines were added in the optimum concentration to three gasolines similar to those described in Table 11. The blended gasoline was composed of cracked and straight-run components which were separately color-stable. They are not, however, the cracked and straight-run components shown in Table 11. The zero value of the ordinate represents the control STRAI#T-RUN sample. The primary and CRACKED secondary amines are shown Si!# O/n~LC"O NOYBCR cram CROOPS to be more effective than the Pca U O L ~ E t e r t i a r y amine. For the FIGURE 4. EFFECT OF Mothree types of gasoline exLECULAR STRUCTURE amined, the primary and s e c o n d a r y a m i n e s were capable of improving the color stability from four to six units, whereas, a one to two unit improvement was obtained with the tertiary amine. In Table I11 the same relation has been shown to hold for the butyl amines. They have been added in the indicated concentrations t o a blended gasoline. The amyl amines are better than the corresponding butyl amines, and this fact confirms the generalization obtained by the data shown in Figure 3. The data of Table I11 also demonstrate the superiority of the higher primary amines. This is borne out either on the basis of molar or of weight per cent concentration.
[$!:F
TABLE111. EVALUATION BASEDON MOLE PER CENT AND WEIQHTPER CENT INITIAL COLOB AMINE 2.6 X 10-4 gr.am mole per liter: Control 30 f n-Butyl 30+ sec-Butyl 30+ tert-Butyl 304n-Amyl 30+ aec-Amyl 304tmt-Amyl 30+ 0.003% b weight: n-But yK 30+ sec-Butyl 30+ tm#-Butyl 30+ n-Amyl 30+ sec-Amyl 304tert-Amyl 30 4-
1 hr. 20 24 25 21 26 26 24
+
24+ 25 21 26 24+ 23
COLOR AFTER:2 hr. 3 hr. 19
17
20 26 24 24
18 23 24 24
+;
24 23
20 26 24+ 20
18 23 4 23+ 18
;:+ ;:
+
4 hr. 16
23 21 17 24 23 24
23 23 16 23 23 18
+
~
0
I
t
J
4
mum o r z u u i c n i t y ~ o s u ~ OF LENGTH OF HYDROCARBON CHAIN FIGURE 3. EFFECT
That the amino group is the part of the molecule responsible for sunlight color stabilization has been fairly well established in preliminary work using ammonia. It was found that small amounts of anhydrous ammonia dissolved in gasoline exercised a stabilizing action against sunlight color deterioration, though the improvement was small and of short duration. The effect of concentration was critical, and, if i t exceeded 0.001 per cent, there resulted on exposure to sunlight a white cloud formation. The modifying effect of substituent groups on amines as color stabilizers was studied by the use of a color-unstable straight-run stock. Ammonia, n-ethyl, n-butyl, and namyl amines were added in their optimum concentration. The curves obtained in exposing these samples to sunlight
So far, the data have been largely presented to show the relationships between the structure of the molecule and its effectiveness as a color stabilizer. T o show concisely what can be accomplished in a practical way by the use of amines, Figure 5 has been prepared. This is a plot of the Saybolt color during sunlight exposure for n-butyl and n-amyl amines in three different gasolines. The straight-run stock was unstable in the sunlight but did not exhibit any instability while stored in the dark. This particular gasoline, which is sweetened batchwise in plant operation, is usually' stable in the sunlight, but it is believed that the color stability had been harmed by use of too much sulfur for sweetening. The cracked gasoline was mildly acid-treated and rerun. The blended gasoline was composed of about 60 per cent of straight-run and 40 per cent of cracked stock. Before exposure, all of the gasolines were treated with 0.003 per cent of the respective amine.
INDUSTRIAL AND ENGINEERING CHEMISTRY
February, 1935
There resulted in each case a definite improvement by the addition of the amines. These data bear out the fact that n-amyl amine is more effective than n-butyl amine. This is especially true in the cracked gasoline. The effect of the amine continues for some time of exposure. There is, of course, a decrease in color as the period of exposure increases but at a retarded rate for the gasoline containing the amines. This is analogous to the action of a gum inhibitor which does not completely stop the formation of gum but permits i t to proceed a t only a diminished rate.
159
months before shipment. A further consideration is the sunlight exposure following dark storage. Since there is no generally accepted test for dark-storage stability, in this work the three accelerated tests described under “Methods of Test” were used. The data obtained are found in Table N. While there is not the same effectiveness exhibited as in sunlight exposure, the trend is toward stabilization. Since the tests in themselves do not correlate well, it is evident that more work is necessary before the full value of amines as darkstorage color stabilizers can be realized. TABLEIV. RESULTSOF DARK-STORAGE TESTINQ
.IO
(Amine concentration, 2.5 X 10-4 gram mole per liter of cracked atock) -COLOR AFTER:------. 12 weekn Steam Bomb INITIAL at 125’ F. heat heat AMINE COLOR (51.7’(2.1 test teat 26 22 22+ 21+ 0 None 26 25 22 25 4n-Amyl 18 26 25+ 2 5f sec-Amyl 17 25 tert-Am yl 26 25 10 None 27 25 n-Amyl 27 21 25+ 13 16 27 ree-Amyl 27 23 26 16 27 26 tert-Amyl
28
w 28
22
m I8
+
16
+
++
UOURS or s u w w r
rnmsJRr
FIGURE5 . SUNLIGHT COLORDETERIORATION
The foregoing have shown clearly that butyl and amyl amines will effectively inhibit color deterioration in straightrun, cracked, and blended gasolines of Midcontinent origin. In addition to these gasolines, the amines find an important use in clay-treated stocks, especially in those cases where the clay is used to high yields (24). It is possible to secure very good initial color by clay-treating, even a t high throughputs. However. the color stability drops off rapidly to an approximately uniform value after about 2000 barrels2 per ton have been treated. It has been found possible by the use of namyl amine to attain the same degree of color stability a t very high throughputs as existed when the clay was still more active. The curves obtained are similar to those shown for the cracked gasoline in Figure 5. DARK-STORAGE COLORSTABILITY The question of dark-storage stability is a t times important. This is especially true where gasoline is stored many 3
Barre1:of 42 gallons capaoity.
-
The sunlight exposure of amine-treated samples after dark storage is given in Table V. The gasoline, which is a straightrun stock, was stored in large tin cans in the presence of air and water for periods up to 6 months. At monthly intervals, quart samples were removed and subjected to sunlight exposure tests. The control sample fell off slightly in initial color and color stability during storage. The samples with amines did the same but the decrease in color stability was not as great as for the control. It is evident that even after a considerable period of storage, the amines are able to color-stabilize a gasoline. Gum determinations (method A) throughout the storage showed that the gum content of the gasoline increased only by 3 mg. on the average. No outstanding gum inhibition was exhibited by the amines.
EFFECT OF SWEETENING. ON AMINES In the event that amines are added t o a gasoline before sweetening, it is well to know the effect of this treatment on stocks containing them. In Table VI are found the results obtained in adding various amyl amines in an 0.003 per cent concentration t o stocks before and after sweetening. In the first instance the requisite amount of amine was added to the sour gasoline, this being followed by sweetening with plumbite and sulfur. No further addition of amine was made to this stock before exposure. The second sample was sweetened in the same manner but no amines were added until after it was sweet. Then the same amount of amine was added before sunlight exposure. In each case the improvement was definite and of a satisfactory proportion, regardless of when the amine was added. While there is little difference between adding the amines before sweetening or after, it must be borne in mind that the amines, particularly the lighter amines,
STABILI~P AFTER STORAGE OVER WATER TABLEV. SUNLIGHT -ORIGINAL AMINHI Initial 1 hr. 28+ 26 n-Butyl 28f 25 aec-Butyl 28+ 27 n-Amyl sec-Amyl t ert-Amyl 28+ 21b Control
$:$
AMINE n-Butyl scc-Butyl n-Amyl
8W-.%myl
tert-Amyl Control
-C , OLOR Initial
2;
AFTER
1 hr.
COLORa-4 2 hr. 3 hr. 21f 210 22+ 21c 26 25
;:+ ii 1&
1Scc
4 MONTH2 hr. 3 hr.
-COLOR Initial
27
28 27+
:$+ 28
(Containing 0.009per cent of amine) -COLOR AFTER 2 MONTHSAFTBR 1 MONTH1 hr. 2 hr. 3 hr. 1 hr. 2 hr. 3 hr. Initial 24 23 210 28 25422 21 23 21 1Sc 28 25+ 23 22 27 25+ 25+ 25 26 1&
!+ !$ 17cc
l6ccc
-COLOR AFTER 5 MONTHSInitial 1 hr. 2 hr. 3 hr.
27+ 28
26 26
25425
2Oc
17~
-COLOR Initial
1 hr.
28
AFTER
-COLOR
Initial 28 28
21
27 28
21 16c
27
6 MONTHS2 hr. 3 hr.
27
AFTER
1 hr.
+:27 27 27 22
3 MONTHB2 hr. 3 hr.
+:26
+ :
26 26 19c
2541Scc
26
25+
160
I N D U S T R I A L A N D E N G I N E E R I N G C H E lMI S T R Y
are slightly water-soluble and such treatment as sweetening is likely to remove portions of them, although in the case of the amyl amines the quantity removed is insufficient to cause a lowered color stability improvement. Also, these experiments were done in the laboratory and should be confirmed by plant operation. TABLEVI. EFFECTOF SWEETENING (0 003 per cent amine in cracked stock, sunlight exposure) INITIAL-COLOR A F T AMINE AMINE~ ~ D D E D COLOR 1 hr. 2 hr. None 26 24 20 n-Amyl Before sweetening 27 26 26 n-Amyl After sweetening 27 25 25 Isoamyl Before sweetening 26 26 24 Isoamyl -4fter sweetening 26 23 23 None 26 23 22 n-grnyl Before sweetening 26 25 25 26 24 24 n-Amyl After sweetening Isoamyl Before sweetening 26 25 25 Iaoamyl After sweetening 26 25 23f aec-Amyl Before sweetening 26 25 25 aec-Amyl After sweetening 26 23 25
Vol. 2i, NO.2
of the amyl amines, makes their use attractive. With the price of these amines a t $1.25 per pound, the cost of using 0.003 per cent is $0.01 per barrel of 42 gallons.
ACKXOWLEDGMENT Acknowledgment is made of the helpful suggestions of H. 11.Steininger, T. H. R3gers, and V. Voorhees. LITERATURE CITED
B R . ~
3 hr. 16 22 23 21 22 20 23 23 21 29 22 21
AN.4LYTIC.4L DETERMINATION O F AMINES
It is possible to determine the amount of an amine that has been added to a sample by an indirect titration. A suitable size of sample is shaken with a known quantity of standard acid. Without removing the gasoline from the flask, the excess acid is titrated with standard alkali using sodium alizarin sulfonate as an indicator. Samples containing as little as 0.00075 per cent of amine have been checked within three units in the fifth decimal place. A blank determination on the gasoline before addition of the amine will indicate the presence of any natural alkalinity for which a correction must be made. COSTS Advances in the commercial production of amines during the past few years have brought the price down to a very reasonable figure. This fact, coupled with the effectiveness
Beard and Reiff, IND.ENG.CHEM.,Anal. Ed., 3, 280 (1931). Bjerregaard, Oil Gas J., 23(40), 96 (1925). Bjerregaard, U. S. Patents 1,761,810 (June 3, 1930) and 1,949,896 (March 6,1934). Brooks, IND. EXG.C H E x , 18, 1198 (1926). Brooks, U. S. Patent 1,748,507 (Feb. 25, 1930). Brown, J.Inst. Petroleum Tech., 19, 115 (1933). Calcott and Lee, U. S. Patent 1,789,302 (Jan. 29, 1931). Ibid., 1,940,445 (Dec. 19, 1933). Cross, Ibid., 1,840,158 (Jan. 5, 1932). Egloff, Ibid., 1,885,190 (Nov. 1, 1932). Egloff, Faragher, Morrell, Proc. Am. Petroleum Inst., 11, S o . 1, Sect. 111,112 (1930). Egloff and Morrell, Chem. & Met. Eng., 29, 53 (1923). Egloff, Morrell, Lowry, and Dryer, Oil Gas J . , 31 (45), 64 (1933). Goode, Re.finer .\-aturaZ Gasoline Mfr., 10, 79 (1931). Imperial Chemical Industries, British Patent 366,041 (Feb. 10, 1932).
Laohman, U. S. Patent 1,790,622 (Jan. 27, 1931). Ibid., 1,809,170 (June 9, 1931). Leslie and Barbre, Ibid., 1,337,523 (April 20, 1920). Mandelbaum, World Petroleum Congr., London, 1933, Proc., 2, 21.
Pierce, N a t l . Petroleum ,\-ews,22, 121 (1930). Richfield Oil Co., French Patent 695,078 (Dec. 11, 1930). Rogers and Voorhees, Oil Gas J.,32(11), 13 (1933). Standard Oil Co. of N. Y . , British Patent 349,247 (March 23, 1929).
Steininger, paper presented before Div. of Petroleum Chemistry a t Twelfth Midwest Regional Meeting of A. C. S., Kansas City, Mo., May 3 to 5,1934. RECEIVED M a y 25, 1934. Presented before the Division of Petroleum Chemistry at the Twelfth Midwest Regional Meeting of the American Chemical Soriety, Kansas City, Mo., May 3 t o 5, 1934.
Ultramicroscopic Study of Irradiated Drying Oils' KENNETHE. MCCLOSKEY AND WESLEYG. FRANCE, The Ohio State University, Columbus, Ohio
T
HE results of investigations by Wolff (11, 12), Slansky (9), Marcusson (4, Morrell (5, 6),and Stutz (IO),together with previous work carried out in this laboratory (8), led the authors to believe that an ultramicroscopic investigation of ultraviolet irradiated oils might throw some light on the changes occurring during the drying process. It was thought that polymerization of the unsaturated acid glycerides in linseed and tung oils might proceed t o such an extent that aggregates of colloidal dimensions would result. Preliminary experiments by Black ( I ) showed that particles detectable with the ultramicroscope were obtained in these oils after short periods of ultraviolet irradiation. In 1931 Freundlich and Albu ( 2 ) announced that light depolarization experiments, as well as viscosity measurements and ultramicroscopic examination, showed that a t a low drying rate colloidal properties were not obtained in pure or siccative linseed oil. However, they suggested that the possibility of obtaining colloidal properties a t higher drying rates was not dismissed by their work.
EXPERIMENTaL PROCEDURE A Siedentopf cardioid ultramicroscope in combination with a small camera producing double-frame negatives on 35-mm. film was used. The source of ultraviolet light was a water-cooled, direct-current, mercury arc lamp operated a t 160 volts and three amperes; 0.06 t o 0.08 cc. samples in small, tightly stoppered, quartz test tubes were subjected to irradiation a t 2.5 cm. from the lamp. After 24 hours of irradiation, many more colloidal particles were present in a commercial linseed oil (Figure 1B)than were initially present (Figure 1A). A restricted Brownian motion was shown by these particles, the restriction in motion being attributed t o the high viscosity of the oil. It was further observed that the viscosity had increased as a result of the irradiation. Optically void Archer-Daniels-Midland P. hl. P. linseed oil (Figure 2-4) was used in a study of the effect of time of irradiation on the formation of colloidal particles. This oil,
