1340 J.K. DAUN, L.A. COOKE AND R.M. CLEAR

REFERENCES 1 . Western Canadian Oilseeds 1984, edited by C.J. Dempster, Cana-

dian Grain Commission Grain Research Laboratory Crop Bulletin No. 156, Winnipeg, 1985. 2. Official Grain Grading Guide, 1985 Edition, Office of the Chief Grain Inspector, Inspection Division, Canadian Grain Commission, Winnipeg, 1985. 3. Robertson, J.A., and W.A. Morrison III, J. A m e r . Oil Chem. Soc. 56:961 (1979), 4 . Official and Tentative M e t h o d s o f the American Oil C h e m i s t s ' Society, Sunflowerseed, Oil content, Method Ai 3-75. 5. Davidson, L.D., in Analytical Chemistry o f Rapeseed and I t s Products. A Symposium, Canola Council of Canada, Winnipeg,

1980. 6. Daun, J.K., J. Amer. Oil Chem. Soc. 53:767 (1976). 7. Ke, P.J., and A.D. Woywoda, Anal. Chem. A c t a 99:387 (1977). 8. Str~ngham, G.R., D.I. McGregor and S. Pawlowski, in Proceedings o f the 4th International Rapeseed Congress, Geissen, DGF, Mfinster, 1974. 9. Mills, J.T., and W.K. Kim, Can. J. P l a n t Sci. 57:375 (1977). 10. Daun, J.K., P.B. Mazur and C.J. Marek, J. Amer. Oil Chem. Soc. 60:961 (1983). 11. M e t h o d s and Procedures o f Seed Testing. Food Production and Inspection Branch, Agriculture Canada, Queen's Printer, Ottawa, 1965. 12. Prairie Grain Varietal Survey, edited by J.O. Wright, Canadian Cooperative Wheat Producers, Regina, 1984. 13. A m e n d e d Description o f V a r i e t y Brassica campestris Tobin, Food Production and Inspection Branch, Agriculture Canada, Ottawa, 1981. 14. Van Caeseele, L., A.W. McGregor and J.T. Mills, Amer. J. Bot.

72:728 (1985). 15. Daun, J.K., and L.D. Burch, J. Amer. Oil Chem. Soc. 61:1117 (1984}. 16. Downey,R.K., in High and L o w Erucic A c i d Rapeseed Oils Production Usage and Toxicological Evaluatior~ edited by Kramer, J.K.G., F.D. Sauer and W.J. Pigden, Academic Press, Toronto, 1983). 17. Daun, J.K., K.M. Clear and J.T. Mills, J. Amer. Oil Chem. Soc. 62:715 (1985}. 18. Stefansson, B.R., in Proceedings o f the International Conference on the Science, Technology and Marketing o f Rapeseed and Rapeseed Products, Rapeseed Association of Canada, Van-

couver, 1970. 19. Baker, G.H., E.N. Greer, J.J.C. Hinton, C.R. Jones and D.J. Stevens, Cereal Chem. 35:260 (1958}. 20. Martens, J.W., W.L. Seaman and T.G. Atkinson, D i s e a s e s o f F i e l d Crops in Canada, A n Illustrated Compendium, Canadian Phytopathological Society, Guelph, 1984, p. 44. 21. Christensen, C.M., and D.B. Sauer, Storage o f Cereal Grains and T h e i r Products, American Association of Cereal ChemistsInc., St. Paul, MN, 1982. 22. Robertson, J.A., G.W. Chapman, R.L. Wilson Jr. and R.B. Russell, J. A m e r . Oil Chem. Soc. 61:768 (1984). 23. Lutey, R.W., and C.M. Christensen, Phytopath. 53:713 (1963). 24. Machacek, J.E., E. Robertson, H.A.H. Wallace and N.A. Phillips, Can. J. P l a n t Sci. 41:288 (1961). 25. McGee,D.C., and C.M. Christensen, Phytopath. 60:1775 (1970). 26. Bottomley, R.A., C.M. Christensen and W.F. Geddes, Cereal Chem. 29.'53 (1952}. 27. Mills, J.T., and R.N. Sinha, Phytopath. 70.'541 (1980). [Received M a r c h 7, 1986]

,%The Determination of Fatty Acid Primary Amides by Capillary Gas Chromatography Dennis A. Brengartner Owens-Illinois,

Inc., O n e SeaGate, Toledo, O H 4 3 6 6 6

A method h a s been developed for t h e determination of 12 primary amides of long-chain f a t t y acids b y capillary column gas chromatography. T h e method uses n o derivatization or sample preparation other than extraction of t h e sample. A variety of commercial amidecontaining materials have been analyzed successfully. The amides, along with other soluble materials, are first separated from t h e host using refluxing 2-propanol containing a n internal standard. T h e fatty acid amides are then identified and measured b y gas chromatography over a programmed temperature range of 200 to 260 C. T h e chromatograms obtained s h o w sharp peaks,u n i q u e retention times and acceptable reproducibility for quantitation. Cis-trans isomers of several of t h e fatty acid amides were tested and f o u n d to b e resolved under t h e conditions employed. F a t t y acid amides are used as lubricating additives in several types of applications in plastic food packaging. F a t t y acid amides are often a d d e d t o polyolefin and vinyl resins in o r d e r t o modify their physical properties. The amides m i g r a t e t o the surface of the plastic article, where

JAOCS, VoL 63, no. 10 (October 1986)

they function as lubricants and static-charge reducers. The t y p e of a m i d e affects the rate of "bloom," or m i g r a tion t o the surface of the plastic article. Both the t y p e and a m o u n t of a m i d e affect the lubricating properties imparted t o the product. Knowedge of the f a t t y acid amides content in the package permits the correlation of the type and concentration of various commercial a m i d e preparations w i t h changes in product performance. Knowledge of the a m i d e s in the product permits the assessment of product/package interactions. The interested r e a d e r is referred t o McKenna (1). The analytical method chosen had t o cope w i t h several complications: (i) The a m i d e s are m i x e d commercially w i t h the resin, but m i g r a t e t o the surface as a result of their dissimilarity t o the m a t r i x and become inhomogeneously distributed. {ii) The a m i d e molecules contain polar and non-polar groups. (iii) There e x i s t c i s - t r a n s isomers of the unsaturated f a t t y acid amides. (iv) Commercial materials consist of m i x t u r e s of f a t t y acid amides r a t h e r than a single species.

1341 DETERMINATION OF FATTY ACID AMIDES As a specific example, commercial oleamide used as a lubricating ingredient in polyolefins was found to contain oleamide, a large a m o u n t of elaidamide, and smaller a m o u n t s of several o t h e r f a t t y acid primary amides, depending on t h e source. The g e n e r a la n a l y t i c a l approach chosen was to extract the amides and o t h e r species followed b y capillary column gas chromatography. Methods for the separation o f f a t t y acid amides u s i n g p a c k e d columns have appeared in the literature {2,3}, b u t l a c k the resolution to s e p a r a t e the cis-trans i s o m e r p a i r s . O t h e r workers have used r e a c tive conditions to c o n v e r t the amides t o nitriles p r i o r t o gas chromatographic separation (4). The m e t h o d presented here provides a q u i c k and reliable isolation o f t h e amides from a v a r i e t y o f host materials followed by f a s t identification a n d m e a s u r e m e n t o f 12 f a t t y acid amides. MATERIALS A N D METHODS

2

11

10

15

MIN

FIG. 1. C h r o m a t o g r a m of a m i d e reference mixture. P e a k 1, benzamide; 2, myristamide; 3, palmitamide; 4, palmitelaidamide; 5,palmitoleamide; 6 , stearamide; 7, e l a i d a m i d e ; 8, o l e a m i d e ; 9 , linoleamide; 10, linolenamide, and 11, erucamide.

TABLE 1

Reagents. The f a t t y acid amides were obtained from

laboratory supply houses (K & K Division of ICN Pharmaceuticals, Plainview, New York, and Pfaltz & Bauer, W a t e r b u r y , Connecticut}. The i n t e r n a l s t a n d a r d chosen was benzamide, an amide material not occurring in t h e samples investigated. The solvents used were ACS r e a g e n t g r a d e or b e t t e r . Sample preparation. The extraction solvent, 2-propanol, was selected f o r its intermediate polarity and its use in the extraction of o t h e rp o l y m e r additives {5,6}. It is a poor solvent for v i n y l and polyolefin r e s i n s b u t a satisfactory solvent f o r t h e additives encountered in this work. Samples were ground t o 20 mesh o r hot-pressed into a thin film p r i o r to extraction. A n accurately weighed sample containing less t h a n 100 mg of f a t t y acid amides was placed in a 50-ml Erlenmeyer f l a s k with a 25-ml p o r t i o n of 2-propanol containing 20.4 mg of t h e benzamide intern a l standard. A boiling chip was added and the sample refluxed for two hr. If necessary, the sample was filtered t h r o u g h W a t m a n No. 41 p a p e r . The filtrate was concent r a t e d u s i n g a hot w a t e r b a t h and d i l u t e d t o 10 ml with 2-propanol. Gas chromatography conditions. Capillary GC was chosen in o r d e r to s e p a r a t e t h e cis and trans isomers of 9-octadecenamide w h i c h were expected to be major ingredients in commercial oleamide. A fused silica 30 m SP-2330 {90% bis-cyanopropyl/10% phenylcyanopropyl polysiloxane) column {Supelco Inc., Bellefonte, P e n n sylvania} with an i n t e r n a l diameter of 0.32 mm and a film thickness of 0.2 t~m was used. The column was operated u s i n g helium carrier gas a t 15 psig yielding a flow r a t e of i ml/min. The column temperature p r o g r a m was a fourmin hold a t 200 C followed by a 10 C/min ramp t o 260 C. The final temperature was held for 10 min. The injector a n d d e t e c t o r temperatures were 240 and 280 C, respect i v e l y . The capillary i n j e c t o r was operated in the split m o d e with a split flow o f 50 cc/min u s i n g a 1 ~1 sample injection. All determinations were carried out on a PerkinE l m e r Sigma 2B gas chromatograph u s i n g a flame ionization detector. A Hewlett-Packard Model 3390A reporting i n t e g r a t o r was used t o collect d a t a . Verification o f experimental conditions. No f u r t h e r recovery of amides from the plastic materials was f o u n d by u s i n g a second extraction with refluxing 2-propanol. A third extraction using refluxing chloroform also showed

Selected C~4 to C~o A c i d Amides

Common name Benzamide Myristamide Palmitamide Palmitelaidamide Palmitoleamide Stearamide Elaidamide Oleamide Linoleamide Arachiamide Linolenamide Behenamide Erucamide

IUPAC name Benzamide Tetradecanamide Hexadecanamide

Retention time, minutes 8.6 9.4 10.9

trans-9-Hexadecenamide cis-9-Hexadecenamide

11.3 11.5

Octadecanamide

12.4

trans-9-Octadecenamide cis-Octadecenamide

13.0 13.2

9,12-Octadecadienamide Eicosanamide 9,12,15-Octadecatrienamide Docos anamide cis-13-Docosenamide

14.3 14.4 15.8 16.8 18.7

no f u r t h e r recovery of amides. There was no degradation of the i n t e r n a l standard d u r i n g the extraction procedure. The extracts were s t a b l e in 2-propanol for a period of a t l e a s t one week. T h e s t a n d a r d solutions, a f t e r refluxi n g two hr, were indistinguishable from t h e unrefluxed s t a n d a r d solution. There was no evidence o f nitrile formation as determined by examining the chromatograms a t the retention times corresponding to nitrile reference materials. The commercialand synthesized f a t t y acid amides were p r e p a r e d as individual solutions a t levels of one to 10 mg/ml. The solutions were chromatographed to locate t h e peak positions o f t h e major species and impurities. Gas chromatography/mass s p e c t r o m e t r y was used to verify the i d e n t i t y o f selected peaks. RESULTS A N D DISCUSSION

Figure i shows the c h r o m a t o g r a m obtained from a reference mixture of f a t t y acid amides. The chromatogram was t y p i c a l of t h o s e obtained in this work. The p e a k s were s h a r p and well separated, permitting accurate q u a n t i t a tion over t h e entire chromatogram. Table 1 lists the species examined in this work along JAOCS, Vol. 63, no. 10 (October 1986)

1342 D.A. BRENGARTNER TABLE 2 Q u a l i t a t i v e and Quantitative R e s u l t s from C o m m e r c i a l Amide Preparations

Percent found

A 4

Species

Sample A

Sample B

Sample C

Myristamide Palmitamide Palmitelaidamide Palmitoleamide Stearamide Elaidamide Oleamide Linoleamide Linolenamide Erucamide

<0.1 2.2 0.1 0.7 5.6 6.7 39.0 18.4 0.6 19.1

0.6 4.8 0.2 3.1 9.7 9.5 61.9 10.1 3.0 <0.1

0.1 2.5 0.2 1.0 9.3 18.4 45.3 4.0 1.7 1.4

Total %

92.4

102.9

83.9

7

2

B

4

C 2

~

lb

15 M I N

FIG. 2. Chromatograms of c o m m e r c i a l a m i d e m a t e r i a l s . Samples A, B and C. Peak 1, benzamide; 2, palmitamide; 3, p a l m i t o l e a m i d e ; 4, stearamide; 5, elaidamide; 6, oleamide; 7, linoleamide, and 8, erucamide.

w i t h their retention times u n d e r the conditions employed. Relative retentions were calculated u s i n g the benzamide internal standard as the time reference. The internal standard has a retention i n d e x of 33.3 in the Kovats system (7). The precision of the method was found t o be within 10% of the a v e r a g e value for each species. This figure included all sampling, preparation and gas chromatography steps. Standard additions were made and recovered within this value also. The accuracy of the m e t h o d is thus expected t o be within 10% of the true value. No b e t t e r statement of accuracy can be made because (i) standard samples were not available for testing, and {ii} the m e t h o d of standard additions is not proof of recovery because the amides and polyolefin are known t o be inhomogeneous. The sensitivity u s i n g the flame ionization detector permitted the measurement of submicrogram quantities of each species. Lower detection limits were not required for this work. Figures 2a, 2b and 2c show the chromatograms obtained from the analysis of t h r e e commercial oleamide materials. T a b l e 2 summarizes the data from t h e s e samples. It can be seen that g r e a t differences e x i s t in b o t h the types of amides present and their amounts. The knowledge of these differences permits the investigation

JAOCS, Vol. 63, no, 10 (October 1986)

5

10

15

MIN

FIG. 3. Chromatogram of polypropylene extract. Peak 1, benzamide; 2, palmitarnide, and 3, erucamide.

6

$

10

15

MIN

FIG. 4 . C h r o m a t o g r a m of plasticized poly(vinylchloride) extract. P e a k 1, benzamide; 2, unknown; 3, di(2-ethylhexyl)-o-phthalate; 4 , stearamide; 5, elaidamide; 6, oleamide, and 7 , erucamide.

of composition and migration rate effects on plastic articles lubricated w i t h f a t t y amides. F i g u r e 3 shows the chromatogram obtained from the e x t r a c t of a polypropylene bottle cap sample containing a commercial a m i d e lubricant. The c l e a n chromatogram demonstrates that the 2-propanol extraction is free from interferences, particularly from polypropylene oligomers. F i g u r e 4 shows the chromatogram obtained from the

1343 DETERMINATION OF FATTY ACID AMIDES e x t r a c t of a plasticized poly (vinyl chloride) bottle cap liner. The di{2-ethylhexyl)-o-phthalate {DOP) plasticizer is a m a j o r feature of the chromatogram. Even t h o u g h the

DOP is a b o u t 30% of the sample, all of the amides except palmitamide can be f o u n d and measured. T a b l e 3 summarizes the analytical data obtained from b o t h polymer extracts.

ACKNOWLEDGMENT

TABLE 3 Qualitative and Quantitative Results from Extracts of PlasticParts

W. Greive prepared and purified the amides used in this work.

Percent found Species Myristamide Palmitamide Palmitelaidamide Palmitoleamide Stearamide Elaidamide Oleamide Linoleamide Linolenamide Erucamide Total

Polypropylene extract

PVC extract

<0.01 <0.01 <0.01 <0.01 <0.01 <0.01 0.01 0.04 0.02 1.1

<0.01 * 0.02 0.02 0.05 0.11 0.30 0.05 0.03 0.40

1.2

1.0

*Interference by DOP.

REFERENCES 1. McKenna, A.L., in F a t t y A m i d e s : Synthesis, Properties, Reactions, and Applications, Witco Chemical Corp., Memphis, TN, 1982, pp. 32-39. 2. Wang, C.N., and L.D. Metcalfe, J. A m e r . Oil Chem. Soc. 61:581 (1984). 3. Frisina, G., P. Buzi and F. Sevini, J. Chrom. 173:190 (1979). 4. Gaede, D., and C. Meloan, Anal. L e t t e r s 6:71 {1973). 5. D4275-83 Test Method for Determination of Butylated Hydroxy Toluene (BHT) in Polymers of Ethylene and Ethylene-Vinyl Acetate (EVA) Copolymers by Gas Chromatography, American Society For Testing And Materials, Philadelphia. 6. Brengartner, D., Anal. Chim. A c t a 173:177 (1985). 7. Kovats, E., Helv. Chim. A c t a 41:1915 (1958). [Received J a n u a r y 24, 1986]

& Derivatization of Keto Fatty Acids, Part IX. Synthesis and Characterization of Oxathiolanes Suhail Ahmad, M. Khan, F. Ahrnad, Nasirullah a n d S.M. Osman* Section of Oils and Fats, Department of Chemistry, Aligarh Muslim University, Aligarh-202 OO1, India

Oxathiolanes are prepared from the condensation of the oxo f a t t y acids w i t h f3-mercaptoethanol u s i n g BF3etherate as catalyst. 10-Oxoundecanoic acid (I) reacts w i t h the r e a g e n t promptly a n d g i v e s 10-(ethylene oxathiolane) undecanoic acid (V). A similar reaction of 9-oxooctadecanoic acid (II) yields 9-(ethylene oxathiolane) octadecanoic acid {VII). Hemimercaptals (VI, V I I I ) are also i s o l a t e d a s m i n o r products in the above reactions. M e t h y l 9,10-dioxooctadecanoate(III) is also found t o react readily a n d affords m e t h y l 9(10)-(ethylene oxathiolane)-10(9)oxooctadecanoate (IX) a s t h e sole product. There is no reaction w i t h 2-oxooctadecanoie acid (IV). The spectral (infrared, nuclear m a g n e t i c resonance, m a s s ) properties of oxathiolanes are detailed.

In recent years oxathiolanes have attracted attention due t o t h e i r pharmaceutical potential (1), antineoplastic activities (2) and as radioprotectants (3). S c a n n i n g of the literature revealed that ketones readily condensed w i t h f3-mercaptoethanol in the presence of various catalysts (4-6) t o furnish oxathiolanes. These sulfur-containing heterocycles also have been reported by the acid catalyzed reaction of T M S enol ethers w i t h 3-mercaptoethanol (7). *To whom correspondence should be addressed.

The resurgence of interest in oxathiolanes for their pharmacological activities and our derivatization program for the synthesis of f a t t y heterocycles (8-10) led us t o undertake the present work on the synthesis of long c h a i n oxathiolanes. Recently, this t y p e of sulfur heterocycle also has been prepared from aft-unsaturated oxo f a t t y esters in our laboratory (11). This paper describes the synthesis and spectral characteristics (IR, NMR, Mass) of c h a i n substituted ethylene oxathiolanes obtained from isolated oxo f a t t y acids/esters.

EXPERIMENTAL PROCEDURES All m e l t i n gpoints are uncorrected. IR spectra (expressed in cm-1) were obtained on a P y e U n i c a m SP3-100 spectrophotometer in nujol mulls. N M R spectra were run in CDC13 on a V a r i a n A60 spectrometer w i t h tetramethylsilane as the internal standard. N M R values are g i v e n in p p m d (s, singlet; br, broad; d, doublet; m, multiplet). Mass spectra were measured w i t h J E O L J M S D-300 at 70 eV. Figures in parentheses a f t e r M S values indicate the intensity of a peak relative t o the base peak (100) and some indication of its source. TLC plates were coated w i t h silica gel. The s p o t s were visualized by charring a f t e r s p r a y ing w i t h a 20% aqueous solution of perchloric acid. Anhydrous s o d i u m sulphate was used as a d r y i n g agent.

JAOCS, Vol. 63, no. 10 (October 1986)