The results clearly show that the campholenyl epoxide esters of the fatty acids employed in compositions 1, 3, and 5 are the best performing plasticizers of the group in terms of ease of processing, low-temperature performance, and flexibility imparted to the plastic compositions. I n these respects they are about comparable to the control (composition 6) but impart thermal stabilization to the plastic composition (curves 1, 3: and 5 of Figure 1) vastly superior to that of D O P (curve 6 ) . There is no explanation a t this time for the discrepancy in the values for extraction loss of compositions 3 and 5. The animal fatty acid contained 48Yc oleic acid. A loss in the order of 6Yc, approximately one-half that obtained for composition 5, Lsould be expected for the ester made from this acid. The campholenyl epoxide esters of the carbocyclic acids (compositions 2 and 4) are decidedly more poorly performing plasticizers and stabilizers (curves 2 and 4, Figure 1). In fact? the composition plasticized isith di-a-campholenyl phthalate diepoxide (curve 2> Figure 1) exhibits an even poorer thermal stability than that of D O P (curve 6 ) . The poor stabilization imparted by the cyclic acid epoxide esters is surprising in vie\s of their oxirane Content: which is equal to or greater than that of the noncyclic acid esters and must be indicative of either a loss in oxirane content during processing or a loiser reactivity of the oxirane group.
Conclusions
a-Campholenol (111) can be esterified with fatty acids. I11 was not rearranged to P-campholenol (VII) in preparation of the ester. T h e a-campholenyl epoxy esters of noncyclic alkanoic or alkenoic acids are acceptable primary plasticizers for poly(viny1 chloride), Lvhich impart middle-range lowtemperature performance and excellent long-term thermal stability to the plastic composition. Carbocyclic esters of acampholenyl epoxide, though compatible, are far less effective plasticizers and stabilizers and contribute little to low-temperature performance. literature Cited
(1) Xrbusow. B., Ber. 68, 1430 (1935). ( 2 ) Food Machinery Gorp.. Inorganic Division, Product Promotion Department. 633 Third Xve.. New York. N. Y . . Technical Data Sh’eet. m-Chloroperbenzoic Acid. 162. (3) Jungnickel. J. L..Peters. E. D.. Polgar. A . \Veiss. F. T.,
“Organic .Analysis.” Vol. I, p. 135, Interscience. New York, 1953. (4) Lewis, J . B.: Hedrick, G. \V,, J . Orp. Chem.. in press. (5) Magne. F. C., Mod, R. R., J . Am. Oil Chemists’ Soc. 30, 269-271 (1933). (6) Tieniann, F.:Ber. 29, 3007 (1896). RECEIVEDfor reviev June 18, 1965 .ACCEPTED September 30. 1965
ADSORPTION AND DESORPTION OF A SURFACE ACTIVE AMINOAMIDE ON AN OXIDIZED IRON SURFACE G. J .
K A U T S K Y AND
M . R .
BARUSCH
Charon Research Go.: Richmond, Caiq.
A study o f the adsorption of a C1*-labeled aminoamide of oleic acid from dilute hydrocarbon solutions on iron filings showed that a thin film of the aminoamide was adsorbed on the surface. The object of the study was to measure desorption of the surfactant into hydrocarbons and to determine if the desorption could b e enhanced b y polar compounds. About 2070 of the adsorbed aminoamide desorbed relatively rapidly into hydrocarbons; the remainder desorbed much more slowly. Polar compounds in hydrocarbon solution promoted desorption of the surfactant. This principle was useful in the operation of product pipelines. Purging a surfactant from the pipeline walls with 2-propanol protected subsequent shipments of petroleum products from contamination and prevented degradation of water reaction properties of aircraft fuels.
and desorption of a surface active aminoamide were investigated in connection Lvirh a field problem encountered in petroleum product pipelines. hfilitary aircraft fuels. after being transported through a product pipeline. occasionallv fail \\ ater reaction tests. This degradation of water reaction properties \\as believed to be due to desorption of surfactants \I hich had been adsorbed on the Ivalls of the pipe during previous shipments of motor gasoline. Motor gasolines often contain small amounts of additives such as corrosion inhibitors, detergents, and carburetor deicing agents, which have a strong tendency to adsorb on metal sur-
A
DSORPTION
faces. .4mong the most effective types of surfactants are the aminoamides 1% hich result from the reaction of aminoethylor hydroxyerhyl-substitutedethylenediamine with a carboxylic acid such as oleic acid or stearic acid (7. 3, 6). The polyfunctionality of such aminoamides promotes stronger adsorption on metal surfaces relative to simple primary or secondary amines (2). IVhen a gasoline containing a surfactant is transported through a pipeline. some of the surfactant is adsorbed on the internal wall of the pipe. The adsorbed film of surfactant can desorb into subsequent shipments of products. Desorption of surfactants into aircraft fuels is particularly VOL. 4
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DECEMBER 1 9 6 5
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Table I.
Adsorption of Surfactant Aminoamide on Iron Filings Fuel Concn. Required Spec@ of SurSurface to Form Adsorpfactant of Iron EquilibSurfactant tion, in Fuel, Fzlings,a rium F i l m , Adsorbed: Mg./Sq. P.P.M. sq. .M. Liters M g. Micron 5 6.0 2.20 3.00 0.50 50 17 0 5 50 14 21 0 83 100 17 5 1 02 16 59 0 95 250 6 0 0 45 6 44 1 07 250 6.0 0.40 6.36 1.06 500 130.0 6.0 143,63 1.10 Determined by BET multipoint gas adsorption method, 7 gram of iron j l i n g s = 7.2 sq, meters. Synthetic f u e l , I/ 1 toluene-isooctane. Temperature, 21-22' C.. Flow rate, 500 ml.lhour.
CONCENTRATION OF SURFACTANT If4 FUEL, FIRM.
Figure 1.
undesirable. The presence of surfactants in fuels can lead to emulsions which could carry water and dirt to the filters. In aircraft, failure of fuel filters is hazardous and must be avoided. Military aircraft fuels, therefore, have tight specifications on water reaction. Frequently, the addition of as little as 1 p.p.m. of a surfactant to such fuels causes failure of the ivater reaction test. It was of interest to study some aspects of this problem in the laboratory. For this study, a n aminoamide representative of a material used commercial1)- was selected and synthesized with a C14 label in the carbonyl group. The tracer was prepared from 0.1 mc. of chromatographically pure l-C14 oleic acid by a reaction \vith hydroxyethyl ethylenediamine according to the procedure described by Barusch? Lindstrom, and Sigworth ( 7 , 4: 6). The aminoamide \vas obtained in 85% radioactive
Table II.
Adsorption isotherm of monooleyl amide of N(2-hydroxyethy1)ethylenediamineon iron oxide at room temperature
yield and in a purity typical of the commercially manufactured material. (The tracer contained 0.270 of unreacted oleic acid.) In typical laboratory experiments, the tagged aminoamide was diluted with nonradioactive compound and incorporated into the hydrocarbon solution in such quantities as to produce a specific activity of about 20 disintegrations per second for 1 p.p.m. of aminoamide. This enabled determination of the surfactant a t concentrations as low as about 0.3 p.p.m. laboratory Apparatus
The laboratory apparatus was a 50-ml. (7ilB-inch i d . ) buret partially filled with iron filings. Uniform samples of iron filings were prepared from commercial-grade, 40-mesh iron
Surfactant Desorbed by Various Fuels
(Milligrams of desorbed surfactant) Sample of Efluent, MI. Fuel 0-100 700-200 200-300 300-550 550-1050 11! Toluene-isooctane 1.17 0,155 0.122 0.313 0.300 JP-4 jet fuel, water-saturated 2.03 0.87 0.72 0.88 1.26 Dry premium gasoline 0.77 0,223 0.0885 0.115 0.178 \\.ater-saturated premium gasoline 1,47 0.1825 0.148 0.356 0.430 Column, 15 g. iron filings = 19.5 sq. meters. Fuel used for saturation, 1!l isooctane-toluene, containing 250 p.p.m. of tagged surfactant aminoamide. Total initial amount of surfactant adsorbed on each column, 23.4 mg.
Table 111.
Total Surfactant Desorbed M g. % 2.06 8.8 5.76 24 6 1.375 5.9 2.5635 11 . o
Summary of Desorption Experiments in laboratory Apparatus
(Milligrams of desorbed surfactant) Sample of E f l u e n t , MI. Fuel
0- 700
700-200
200-300
300-550
methanol 4.5 0.45 0.42 0.42 5.85 0.65 0,505 ethanol 0.234 10.2 1.37 0.74 2-propanol 0.86 2.1 0.56 0.41 n-butyl alcohol 0.685 0.71 isobutyl alcohol 1.19 0.435 0.63 2.02 0.575 0.394 n-amyl alcohol 0.82 0.294 lauryl alcohol 0.65 0.18 0.4 0.466 0.28 octanoic acid 2.77 0.45 0.885 0.585 5.45 1.5 oleic acid I "/c tetrapropenyl succinic acia b.43 I .5b u .'I50 1yo ethyl acetate 6.1 0.48 0.295 0.375 1yGoctylamine 5.0 1.2 0.95 0.9 1,45 0.685 1Yc octylamine acetate 12.2 2.15 1Fcoctylamine tridecyl phosphate 9.5 2.8 1.06 Column, 19.5 sq. m. of iron oxide surface. Fuel used for saturation, 1i l toluene-isooctane containing 250 p.p.m. of surfactant. Total initial amount of tracer adsorbed on each column, 23.4 mg. Surface area of iron filings, 1.4 sq. m./gram. ~~
234
l&EC
_
_
_
_
~
~
PRODUCT RESEARCH A N D DEVELOPMENT
550- 1050
0.85 0.088 0.86 0.57 0.437 0.56 0.455 0.83 0.565 0.97 1.26
Total Surfactant Mg. 6.700 7.327 4.030 4.325 3.455 4,369 1.979 4.796 8.420 2.616 7.815 9,020 17.745 13.010
Desorbed
70 28.6 31 . O 60.0 18.5 15.0 18.6 8.5 20.0 36.0 54.0 33.4 38.0 74.0 55.6
2-Methyl-1 -propanol
-
1 -Pentono1
E%i
Methanol Ethanol 2-Propanol
1 -Butanol
' -0odeconol
!2zzzZa !Bzza LzzZz I
I
I
t
I
I
I
)
0
IO
20
30
40
50
60
70
Figure 2. Relative effectiveness of alcohols as purging agents Per cent of surfoctant amine monolayer desorbed (using 10.5 ml. of alcohol in 15-gram column of iron filings)
filihgs by first screening the particles through 35- and 42-mesh screens and then shaking them ten successive times in toluene, each time decanting the suspended dust. The surface of the iron filings was not chemically reduced and was mostly iron oxide. formed by atmospheric oxidation. This surface is believed to be similar to the iron surface of a pipeline. In a typical experiment with a column containing 15 grams of iron filings, the surface (determined by adsbrption of nitrogen) corresponded to 88 feet of a perfectly smooth 8-inch pipe. A 1 to 1 mixture of toluene and isooctane was passed through a column a t a rate of 500 ml. per hour a t 22' C. T h e surfacevolume ratio in the laboratory was 200,000 to 300,000 times as large as that of a typical pipeline. To minimize the mixing of products, qipelines are operated under conditions of turbulent flow; in these laboratory experiments, the flow was essentially laminar. T h e quantity of aminoamide adsorbed on the iron oxide surface was determined by the difference of specific activity (distintegrations per second per ml.) between the fuel charged and incremental volumes of effluent. Counting was performed on a scintillation counter, Model CF-1. Res u Its
I n the first series of experiments, the effect of concentration of the aminoamide on adsorption was studied. T h e concentration ranged from 5 to 500 p,p.m. T h e surface area of iron oxide (iron filings) used in the experiments was about 1.2 sq. meters per gram as determined on the Perkin-Elmer-Shell spectrometer using the multipoint BET method (3). Table I summarizes the laboratory data. T h e amount of aminoamide adsorbed increased with the concentration of surfactant in the hydrocarbon mixture. However, essentially no additional aminoamide was adsorbed when the concentration was raised above 250 p.p.m. This is shown graphically in Figure 1. The maximum amount of surfactant adsorbed on iron filings was about 1.1 mg. per sq. meter. T h e general shape of the adsorption isotherm is indicative of a strong bond between the surfactant and the surface (chemisorption). A Hirschfelder model of the aminoamide was constructed to estimate the average area of attachment of one molecule. Assuming that only the polar end of the molecule would adhere to the surface, the average area of attachment of one molecule was estimated to be about 100 AZ. Using this figure, it was calculated that about 1.3 mg. of aminoamide would be required per square meter of surface to form a monomolecular layer. T h e experimental value of 1.1 mg. is close to the calculated quantity. Columns saturated with the surfactant aminoamide were used in elution experiments. The saturated film was produced by passing a hydrocarbon solution of the tagged surfactant (500 p.p.m.) through the column until the radioactivity of the effluent fuel (isooctane-toluene) was equal to that of the solu-
tion entering the column. These columns were eluted by gasolines and by jet fuels. T o simulate the usual conditions in the field, two of the fuels were saturated with water. The amount of surfactant desorbed was calculated by counting radiocarbon in the effluent. Data summarized in Table I1 show that only a portion of the surfactant was desorbed from the iron oxide surface into the fuels. Under the conditions studied, as much as one quarter of the aminoamide layer was desorbed into the JP-4 jet fuel. T h e wet JP-4 fuel tended to desorb the surfactant more effectively than the other fuels. T o provide greater accuracy, a larger-scale experiment was carried out with a column containing 100 grams of iron oxide. Samples (100 ml.) of fuel leaving the column were collected, evaluated in the water reaction test ( 5 ) ,and counted for radioactivity. Correcting for the retained volume on the packed column, 7600 ml. of jet fuel saturated with water had to pass through the column before a 100-ml. sample of fuel could be collected with water reaction performance that would satisfy the military specification. Each incremental sample collected contained progressively less surfactant, and the last 100-ml. sample failing the water reaction test contained 3.6 p.p.m. of surfactant. Counting of the tagged surfactant in the effluent samples of fuel from the column showed that about 20% of the aminoamide adsorbed on iron oxide columns desorbed into the first 300 ml. of effluent relatively rapidly and further desorption occurred much more slowly. The rate of desorption was substantially accelerated. and the over-all quantity of surfactant desorbed was greater when polar materials were added to the fuel. These compounds function a t low concentrations as purging agents by displacing the surfactant from the iron oxide. I t was decided to evaluate the effect of polar compounds on the desorption process in the hope of finding an effective purging agent for pipeline use. One per cent solutions of a number of compounds (alcohols, carboxylic acids. esters, amines, and amine salts) were evaluated. T h e size of the column was reduced to 15 grams of iron filings for economy of time and solvents. T h e columns were first saturated with the tagged aminoamide (250 p.p.m. iil synthetic fuel), then eluted with a total of 1050 ml. of fuel containing lyGof the purging agent; the rate of flow was 500 ml. per hour. The surfactant concentration in the effluent was determined by the counting technique. Table I11 shows that octylamine acetate was the most effective purging agent tested. However, this acetate is not economically attractive. Lower molecular weight aliphatic alcohols as a group were effective in purging, and 2-propanol was the outstanding alcohol. Figure 2 compares the effectiveness of seven alcohols as purging agents, in terms of percentage of the adsorbed aminoamide removed. I n each case, the indicated per cent of surfactant was desorbed into 1050 ml. of fuel containing 1% of the alcohol. Further desorption of the aminoamide by fuel containing the purging agent would occur a t a considerably slower rate. T h e laboratory data show that 1050 ml. of a 1% 2-propanol solution purged 60% of the adsorbed aminoamide from the surface. T h e effect of concentration of 2-propanol on the rate of elution was studied. A large iron oxide column (100 grams of iron oxide) was first saturated with the tagged aminoamide, then eluted with pure 2-propanol. T h e experiment was repeated with progressively less copcentrated solutions of 2propanol in 1 to 1 isooctane-toluene-Le., 10, 1,0.1, and 0.0170. These experiments showed that the tagged aminoamide was VOL. 4
NO. 4
DECEMBER 1 9 6 5
235
only partially removed from the surface by 2-propanol, regardless of the concentration. For the same amount of alcohol, the 1y0solution of 2-propanol was more effective than the pure alcohol. The maximum volume of fuel used in the desorption experiments was 2000 ml. At lower concentrations of 2-propanol (0.1 and O.Ol%), the surfactant was removed from the surface a t an impractically slow rate. These results indicate that a purging agent, such as 2-propanol, introduced into a pipeline after the transport of a surfactant-containing fuel should prevent the contamination of following surfactant-free fuels and eliminate the degradation of water reaction properties. In each laboratory experiment, after a purge was completed, jet fuel (JP-4) was passed through the column and its water reaction was tested ( 5 ) . In all cases, with the exception of the lauryl alcohol purge, the water reaction of the effluent, JP-4, was good. Discussion
These experiments are useful in understanding some of the problems associated with adsorption and desorption in a products pipeline. However, the laboratory results can be expected to correlate only qualitatively with pipeline experience. Pipelines are operated under conditions of turbulent flow and with vastly different surface-volume ratios than used in these studies. The surface roughness of a pipeline will vary greatly and depend on the amount of rust present; thus, the surface area is exceedingly difficult to measure. Consequently, accurate predictions of field performance based on laboratory results are not possible a t this time. From these studies, it is expected that the internal wall of a pipeline M ould absorb approximately a monomolecular layer of the additive from a shipment of gasoline containing an aminoamide surfactant. Taking a 100-mile-long smooth 8-inch pipe as an example, it can be calculated from the laboratory data
that 110 grams of the surfactant would be adsorbed on the pipeline wa!ls. A small amount of roughness might easily raise the total available surface tenfold. Then about 2l/2 pounds of the additive could be adsorbed. If a jet fuel, free of surfactant, were passed through this hypothetical line, about 25% of the surfactant would be desorbed into the jet fuel. Depending on surface roughness, this would lead in the considered line to a contamination of about 250 to 2500 barrels of jet fuel with a n average of more than 1 p.p.m. of the surfactant. I n actual product pipeline experience, considerably larger shipments of jet fuel failed the water reaction test. The effective displacement of surfactant from iron filings as observed in the laboratory led us to suggest the purging of pipelines with 2-propanol. \Ve have found by actual field experiments that three barrels of 2-propanol, introduced a t the interface between shipments of a surfactant-containing motor gasoline and jet fuel, are sufficient to purge a 100-mile, 8-inch pipeline and maintain acceptable water reaction properties of aircraft fuels. Literature Cited
(1) Barusch, M. R., Lindstrom, E. G., U. S. Patent 2,839,373
(April 30, 1958).
(2) Bergman, J. I., “Corrosion Inhibitors,” pp. 197-209, Macmillan, New York, 1963. (3) Ettre. L. S., Ciedinski. E. SV.. “Determination of Surface \
I
Areas by Gas Ch;omatographic Methods,” “Ultrafine Particles,’’ Electrochemical Society Symposium, 1963, p. 393. (4) Lindstrom, E. G., Barusch, M. R., U. S. Patent 2,839,372 (June 17, 1958). (5) Military Water Reaction Test, MIL-J-5624E. (6) Sigworth. H. SV., Lindstrom, E. G., Barusch, M. R., U. S. Patent 2,839,371 (June 17, 1958). RECEIVED for review May 6, 1965 A C C E P T E D September 28, 1965 Division of Petroleum Chemistry, 149th Meeting, ACS, Detroit, Mich., April 1965.
ACETYLENIC NONIONIC SURFACTANTS Ethovlation of Aceplenic Alcohols and Glycols, A New Class of Unique Wetting Agents M . W. LEEDS,
R. J . T E D E S C H I , S . J . D U M O V I C H , A N D A.
W . CASEY
Central Research Laboratory, A i r Reduction Co., Inc., M u r r a y Hill,N . J .
YDROPHOBIC
moieties containing active hydrogen have
H long been ethoxylated on a large scale to make nonionic
surfactants. Compounds containing hydroxyl groups including phenols and long-chain alcohols and glycols have been one of the major types to be ethoxylated. T h e tertiary acetylenic alcohols and glycols were found in our laboratory to possess novel surfactant properties by virtue of the inclusion of the acetylenic group in the molecules. Compounds such as tetramethyldecynediol, dimethyldecynediol, and hexadecynediol are unique, nonionic, nonfoaming surfaceactive agents which retain their excellent properties even a t relatively low concentrations in aqueous solutions. However, for broader applications higher concentrations were needed and because of the low solubility of the acetylenic diois, performance was poor. For this reason, it was considered desirable to attempt to ethoxylate the acetylenic alcohols and glycols, rendering them more soluble while retaining their surface236
I & E C P R O D U C T RESEARCH A N D DEVELOPMENT
active properties. This work was undertaken with a limited degree of success by earlier investigafors. Nazarov and Romanov (7) described the reaction of vinyl acetylenic alcohols with ethylene and propylene oxide to form a mixture of mono-: di-, and poly- adducts. This method involved reaction of vinylacetylene with ketones in dry ether using K O H . The resulting K O H complex then reacted in situ with ethylene oxide. A large amount (about 5070) of unreacted vinyl acetylenic carbinol was, however, recovered. The resulting products were a mixture of monoand higher adducts. KO reference was made to their surfactant properties. More recently Lagucheva ( 5 )made a large excess of dimethyl (vinyl ethynyl) carbinol (vinylacetylene-acetone carbinol) react with ethylene oxide in the presence of N,,V-dimethylaniline in a n autoclave a t 60’ to 85’ C . for 7 hours. This gave a 69% yield of the desired mono-adduct and 60y0 of the di- adduct
