[CONTRIBUTION FROM THE STERLING CHEMISTRY
LABORATORY, YALE
UNIVERSITY]
CONTRIBUTIOXS TO THE STUDY OF MARINE PRODUCTS. XI. THE OCCURRENCE O F OCTADECYL ALCOHOL, BATYL ALCOHOL, AND CETYL PALMITATE I N GORGONIAS’ C. ALBERT KIND
AND
WERNER BERGMANN
Received June 29, 1942
It has been shown in previous communications (1, 2) that coral-reef building animals contain significant quantities of unsaponifiable matter. The suggestion has been made (1) that this material is eventually removed from circulation by becoming embedded in the ever-growing reef, acting like a vast storehouse of compounds, which may be looked upon as potential precursors of petroleum. Gorgonias have long been recognized as contributors to the formation of reefs. The organic chemistry of these animal colonies has been the subject of a number of investigations; these have been concerned, however, almost exclusively with the iodine-containing horny stem. This part of the colony contains only small amounts of ether-acetone-soluble material. The bulk of the fatty substances is concentrated in the living, calcareous, external layers, from which they may readily be extracted by lipid solvents. As far as the authors are aware, no information concerning the composition of these lipids appears to be available a t present. In connection with systematic studies on the distribution of sterols among marine invertebrates, which are in progress in this laboratory, a quantity of nonsteroid alcohols was obtained from the unsaponifiable fraction of the gorgonia, Plexaura jlexuosa. This material had been obtained by first removing the sterols by means of digitonin, and by subsequent subdivision of the remainder into an alcoholic and non-alcoholic fraction by way of the sulfuric acid esters of the alcohols. This method of separation, which has already been shown by one of the authors (3) to give satisfactory results, is analogous to the one, first used by Natelson and Sobel (4) for the isolation of sterols from mixtures. Recently Sobel and Spoerri ( 5 ) have recommended a modified procedure as a cheap and convenient substitute for the digitonin method in the isolation and quantitative determination of sterols. The fact, however, that this sulfate method may also be used with advantage for the isolation of alcohols other than sterols, makes it obvious, that in its present form it may replace the digitonin method only in such cases where the presence of non-sterol alcohols is definitely contraindicated. The alcohols were recovered from the sulfates by acid hydrolysis as recommended by Butenandt and Westphal(6). The crude, sterol-free, alcoholic fraction from Plexaura JEexuosa was a colorless, wax-like material. It was at first believed to consist principally of cetyl alcohol, as did the corresponding fraction from corals (2). Fractional distillation of the material in vacuo, however, showed that it contained two principal components. The first fraction, representing more than fifty per cent of the ‘The material in this paper constitutes part of a dissertation submitted by C. A. Kind in partial fulfillment of the requirements for the Ph.D. degree, Yale University, June 1942. 424
CONSTITUENTS OF GORGONIAS
425
material, melted a t 55-56" after repeated recrystallizations. Analysis of the alcohol agreed well for C18H3,0H, or octadecyl alcohol for which the map. 58' has been reported. The phenylurethan of the gorgonia alcohol melted a t 76" or about three degrees below the melting point reported for octadecylphenylurethan. Mixtures of the corresponding alcohols and phenylurethans melted between the melting points of the respective substances. It was assumedtherefore that this gorgonia alcohol was octadecyl alcohol containing small amounts of impurities. The correctness of this assumption was borne out by the fact that the m-dinitrobenzoate, m.p. 76.5", of the gorgonia alcohol analyzed accurately for octadecyl m-dinitrobenzoate, and that treatment of the alcohol with hydriodic acid gave octadecyl iodide, m.p. 34', which gave no depression of the melting point when mixed with an authentic sample. As far as the authors are aware, this is the first time that octadecyl alcohol has been isolated from lower marine invertebrates. The second fraction from the fractional distillation of the gorgonia alcohols was a mixture, which will be discussed below. The residue from the distillation represented about fifteen per cent of the mixture. Treatment of the material with phenylisocyanate yielded a compound of map. 101-102', which analyzed satisfactorily for the bis-phenylurethan of an alcohol of the formula C21H4403. The data agree well with those reported for the bis-phenylurethan of batyl alcohol, m.p. 101-102' (7), and a mixture of the two compounds showed no depression of the melting point. Hydrolysis of the bis-phenylurethan of the dihydric gorgonia alcohol gave batyl alcohol, HOCHzCHOHCH20(CH2)17CH3, m.p. 68-69', which like the batyl alcohol from fish oils (8) and bone marrow (7) showed a small positive rotation of (cy):5 1.4". The identity of the dihydric gorgonia alcohol with batyl alcohol was finally established by the conversion of the former into octadecyl iodide, m.p. 34', which gave no depression of the melting point when mixed with an authentic sample. As far as the authors are aware this is the first time that the presence of batyl alcohol in lower marine invertebrates has been definitely established. The second, or middle fraction, from the distillation melted at 64", and gave a phenylurethan of m.p. 95-96'. The physical properties and analytical data of this fraction and its derivatives indicated that it was a mixture of batyl alcohol and some octadecyl alcohol. In this connection it is of interest to note that Drummond and Baker (9) have reported the melting point 64" for a sample of batyl alcohol isolated from a mixture containing octadecyl alcohol. These authors have emphasized the difficulties encountered in separating such a mixture. Quite different results were obtained with the gorgonia, Xiphogorgia sp. The calcareous layers of this colony are rather thin, and their separation from the stem is difficult. The entire material was therefore extracted with acetone.2 Treatment of the acetone extract with alcohol led to the separation of a greenish It was identified as cetyl wax, which after purification melted a t 50-50.5'. palmitate by direct comparison and by its hydrolysis to cetyl alcohol and palmitic
+
*The authors express their gratitude to Merck and Co. for the extraction of thematerial.
426
C. A. KIND AND WERNER BERGMANN
acid. The sterol-free, alcoholic fraction of the unsaponifiable matter of this gorgonia, prepared as described above, consisted almost entirely of cetyl alcohol. The results obtained with Xiphogorgiac are therefore quite analogous to those obtained with corals (2). EXPERIMENTAL
All melting points are corrected. Preparation and fractionation of the non-sterol alcohols from Plexaura flexuosa. Twentyfive grams of sterol-free unsaponifiable matter was dissolved in 150 cc. of chloroform and 75 cc. of pyridine. The solution was cooled in an ice-bath, and a solution of 7.5 cc. of chlorosulfonic acid in 50 cc. of chloroform was added dropwise under vigorous stirring. The mixture was left standing a t room temperature overnight and then refluxed for two hours on the steam-bath. Most of the chloroform was then distilled off, and ether was added to the remainder. The suspension was then shaken vigorously with 150 cc. of 2 N sodium carbonate solution until the sodium salts of the sulfuric acid esters had largely separated. Concentrated sodium chloride solution was then added, and the ether layer separated, a process which was greatly facilitated by centrifugation. The salts were filtered, dried in vacuo, and exhaustively extracted with ether. They were then refluxed for six hours with 200 cc. of ethanol and 100 cc. of 5 N sulfuric acid. The alcohols, which separated as an oily layer on the surface of the liquid, solidified a t room temperature. They were extracted with ether, and the ether extract was washed, dried, and evaporated to dryness. The crude alcohols (12 g.) were then transferred into a small distilling flask with a built-in Widmer column and subjected to fractional distillation a t about 0.5 mm. The first fraction, A, came over a t a distilling temperature of 100-105" and a bath temperature of 152155", and the second fraction, B, a t 135-140" and 180-185" respectively. The distillation was then interrupted and the residue, fraction C, removed from the flask. Isolation of octadecyl alcohol. Fraction A, (7 g.) came over as an almost colorless oil which solidified at room temperature. After repeated recrystallizations from acetone i t melted a t 56-57'; the mixed melting point with octadecyl alcohol of m.p. 58" was 56-58'. Anal. Calc'd for ClaHssO: C, 79.92; H, 14.16. Found: C, 79.94; H , 13.88. Octadecylphenylurethan. The alcohol was refluxed for three hours with a solution of phenylisocyanate in benzene. The solution was then evaporated to complete dryness in vacuo a t loo", and the residue recrystallized from benzene and methanol; m.p. 76". The mixed melting point with octadecylphenylurethan of m.p. 78-79" was 77-78". Anal. Calc'd for CzsH43NOz: N , 3.60. Found: N, 3.70. Octadecyl m-dinitrobenzoate. The alcohol was treated with m-dinitrobenzoyl chloride in dry pyridine. The crude, reddish product was dissolved in low-boiling petroleum ether and decolorized with Norit. After several recrystallizations from petroleum ether the compound was obtained in the form of small, colorless needles, m.p. 76.5'. The m-dinitrobenzoate of authentic octadecyl alcohol was prepared in an analogous manner. It melted at 77.5", and a mixture of the two compounds melted a t 76-77". Anal. Calc'd for CZsH4oNzOa:C, 64.63; H, 8.68. Found: C, 64.53; H, 8.68. Octadecyl iodide. Five hundred milligrams of the alcohol, 20 mg. of red phosphorus, and 25 mg. of freshly sublimed iodine were heated for four hours at 145-150". After cooling, the mixture was treated with ether, and the ether extract washed successively with water, 5% sodium hydroxide solution, and water, dried, and evaporated to dryness. The residue was recrystallized several times from an acetone-ethanol mixture, m.p. 33-33.5'. The mixed melting point with an authentic sample of octadecyl iodide of m.p. 34" was 33-34'. Batyl-bis-phenylurethan. Fraction C was treated with phenylisocyanate in the manner described above, and the reaction product was recrystallized several times from methanol;
CONSTITUENTS OF GORGONIAS
427
m.p. 100.5-101". The mixed melting point with an authentic sample of batyl-bis-phenylurethan3 of m.p. 100-101" was 100-101". Anal. Calc'd for CssHsaNzOs: C, 72.16; H , 9.28. Found: C, 72.10; H, 9.53. Batyl alcohol. The alcohol was prepared by refluxing the bis-phenylurethan for six hours with 5y0 sodium hydroxide in methanol. After several recrystallizations from dilute acetone i t melted a t 68-69'. The mixed melting point with an authentic sample of batyl alcohol3 of m.p. 70" was 68-70'. (CY): $1.4" (45.1 mg. in 3.0 cc. of chloroform). Anal. Calc'd for CZIHUOS: C, 73.25; H , 12.79. Found: C, 73.01; H , 12.69. Octadecyl iodide. The alcohol was refluxed for 150 minutes wit6 hydriodic acid, spec. gr. 1.7, and the iodide was isolated according to Heilbron and Owens (10); m.p. 33-34". The mixed melting point with octadecyl iodide of m.p. 34" was 3334". Anal. Calc'd for ClsH8,I: C, 56.83; H, 9.80. Found: C, 56.86; H , 9.72. Fraction B . After four recrystallizations from acetone, fraction B gave 0.8 g. of a colorless, crystalline substance of m.p. 62-64'. (Calc'd for CnHuO~:C, 73.25; H, 12.79; Found: C, 74.39; H , 13.19.) The phenylurethan of the substance melted a t 95-96'. (Calc'd for CSSHMN206: C, 72.16; H, 9.28; Found: C, 71.70; H , 9.49.) It appears therefore that this fraction is a mixture of batyl and octadecyl alcohols and probably some other constituents. Isolation of cetyl palmitate from Xiphogorgia s p . The acetone extract of Xiphogorgia sp. was diluted with twice its volume of warm ethanol, and the undissolved material was filtered. I t represented a greenish wax, which was subjected to repeated treatments with Norit in acetone. -4colorless material of m.p. 50-51" was eventually obtained, which gave no depression of the melting point Then mixed with an authentic sample of cetyl palmitate. The compound was identified as cetyl palmitate by its hydrolysis to cetyl alcohol, m.p. 49", and palmitic acid, m.p. 62.5" (2). SUMMARY
Octadecyl alcohol and batyl alcohol have been isolated from the unsaponifiable material of the gorgonia, Plexaura jlesuosa. Cetyl palmitate has been isolated from the acetone extract of the gorgonia, Xiphogorgia sp. NEWHAVEN,CONN. REFERENCES BERGMANN AND LESTER,Science, 92, 452 (1940). LESTERAND BEROMANN, J.Org. Chem., 6,120 (1941). BERGMANN, Ann. Entomol. SOC.Am., 31, 315 (1938). AND SOBEL, J . Biol. Chem., 109,687 (1935). NATELSON J . Am. Chem. SOC.,64, 361 (1942). SOBELAND SPOERRI, BUTENANDT AND WESTPHAL, Ber., 69, 447 (1936). HOLMES, CORBET, GEIGER,KORNBLUM, AND ALEXANDER, J . Am. Chem. SOC.,63, 2607 (1941). (8) DAVIES,HEILBRON, AND JONES, J. Chem. SOC.,1933, 166. AND BAKER, Biochem. J., 23, 274 (1929). (9) DRUMMOND (IO) HEILBRON AND OWENS, J . Chem. SOC., 1928, 942. (1) (2) (3) (4) (5) (6) (7)
3The authors are indebted to Drs. H. N. Holmes and N. Kornblum for a sample of this compound.
