Fatty acids of Thespesia populnea: Mass spectrometry of picolinyl esters of cyclopropene fatty acids

Thespesia populnea belongs to the plant family of Malvaceae which contain cyclopropane and cyclopropene fatty acids. However, previous literature reports vary regarding the content of these compounds in Thespesia populnea seed oil. In this work, the content of malvalic acid (8,9‐methylene‐9‐heptadecenoic acid) in the fatty acid profile of Thespesia populnea seed oil was approximately 7% by GC. Two cyclopropane fatty acids were identified, including dihydrosterculic acid. The methyl and picolinyl esters of Thespesia populnea seed oil were also prepared. The mass spectrum of picolinyl malvalate was more closely investigated, especially an ion at m/e 279, which does not fit the typical series of ions observed in picolinyl esters. It is shown that this ion is caused by cleavage at the picolinyl moiety and contains the fatty acid chain without the picolinyl moiety. This type of cleavage has previously not been observed prominently in picolinyl esters and may therefore be diagnostic for picolinyl esters of cyclopropene fatty acids. The NMR spectra of Thespesia populnea methyl esters are also discussed. Practical applications: The work reports the fatty acid composition of Thespesia seed oil whose derivatives have not yet been extensively utilized for industrial purposes, for example, biodiesel. Knowing this composition is essential for understanding potential uses and, for example, in case of biodiesel the fuel properties. Besides this issue, some data (mass spectrometry and NMR) crucial for obtaining the composition information are analyzed in detail. The biodiesel properties of methyl esters of Thespesia populnea will be reported separately.     

Homogeneously catalyzed hydrogenation and gas-liquid chromatographic analysis of the methyl esters of cyclopropene fatty acids

Various concentrations of cyclopropene fatty acids have been determined down to 0.2% by the use of gas liquid chromatographic (GLC) analysis of the methyl esters of fatty acids that have been quantitatively hydrogenated using a homogeneous transition metal complex catalyst. The effectiveness of the use of bromotris(triphenylphosphine)-rhodium(I), Br(P(C₆H₅)₃)₃Rh, as a homogeneous hydrogenation catalyst to convert the cyclopropene ring to a cyclopropane ring has been evaluated and compared with the analogous chloro- and iodo-complexes. The hydrogenation/GLC method of analysis has been compared with the method of titration with hydrogen bromide in benzene and with the method involving the use of high resolution nuclear magnetic resonance (NMR).     

Gas-liquid chromatographic analysis of cyclopropene fatty acids

A gas-liquid chromatographic method is described for the quantitative estimation of cyclopropene fatty acids as their methyl mercaptan derivatives. This method estimates individual cyclopropene acids as well as normal and cyclopropane acids. Nine seed oils were analyzed for their cyclopropene fatty acid content. Evidence was obtained for the presence of a cyclopropene fatty acid of shorter chain length than malvalic inAlthaea rosea cav and one with a higher chain length than sterculic inBombacopsis glabra seed oil. This method is less accurate for cottonseed oil than for the other oils tested because of the appearance of some unsymmetrical peaks of unknown origin. The mercaptan derivatives of the cyclopropene acids may be isolated by silver ion thin-layer chromatography. Small amounts of cyclopropane fatty acids were found in a number of the oils analyzed for cyclopropene fatty acids. Presented at the AOCS meeting, Chicago, October 1964.     

Glycidyl esters. II. Synthesis of esters of commercial and pure fatty acids

The reaction of salts of earboxylic acids with epichlorohydrin in the presence of quaternary ammonium halides to form glycidyl esters has been demonstrated to be applieable to a variety of acids derived from fats, including commercial mixtures. The glycidyl esters of pelargonic, lauric, oleic, dimerized linoleic, ricinoleic, behenic, and sebacic acids as well as those of the fatty acids derived from tallow, wool wax, and soya oil have been prepared in 80–95% yields and purities. Eastern Utilization Research and Development Division, Agricultural Research Service, U.S. Department of Agriculture.     

The biosynthesis of cyclopropane and cyclopropene fatty acids in plant tissues

The biosynthesis of cyclopropane and cyclopropene fatty acids was investigated in seeds of several species of the order Malvales, including species with a high content of sterculic acid, a high content of malvalic acid, and a low content of these cyclopropene fatty acids. The fatty acid composition of the lipids in young and developing seeds is compared with particular attention to variations in cyclopropane and cyclopropene fatty acid contents. Incubation studies employing several¹⁴C compounds indicate that the methyl group of methionine is the most likely precursor of the ring-methylene carbon. A pathway for the synthesis of the cyclopropane and cyclopropene fatty acids is postulated. The origin of malvalic acid is also considered.     

Addition of chlorine to unsaturated fatty acids and esters

Summary Methyl oleate, oleic acid, and ethyl linoleate were chlorinated with elemental chlorine at temperatures near −20°C. Approximately quantitative yields of the addition products were obtained, with little or no concurrent substitution. The products prepared in this manner had not previously been reported in the pure state. Two new compounds, ethyl tetrachlorostearate and tetrachlorostearic acid, were prepared. Methyl dichlorostearate was found to distil with no apparent decomposition at 190–200°C. under pressures below 1 mm. Removal of the chlorine atoms required more drastic conditions that removal of bromine atoms from the same positions and was accompanied by complicating side reactions. Journal Paper No. 755 of the Purdue University Agricultural Experiment Station, Lafayette, Ind.     

Potentiometric titration of cyclopropene esters

The quantitative determination of cyclopropene acids occurring as esters in seed oils can be made by a direct titration with hydrogen bromide in toluene, but the color indicator used heretofore to determine the end point presented problems. A potentiometric titration that avoids these problems was devised. A silver-silver chloride indicator electrode and a calomel reference electrode connected to the titration cell by a salt bridge were employed. The precision of the cyclopropene analysis of purified samples seems to depend primarily on the accuracy to which the amount of titrant can be determined. At the 1% level, reproductible values to about ±0.01% are obtained. One of the facilities of the Southern Region, Science and Education Administration, U.S. Department of Agriculture.     

Mass spectra of TMS esters of deuterated decanoic acids and of TMS ethers of deuterated decanols

Mass spectra of trimethylsilyl esters of nine specifically deuterated decanoic acids and of trimethylsilyl ethers of the corresponding deuterated decanols and of tri[²H₃] methylsilyl derivatives of most of the acids and of decanol have been measured. The fragmentation patterns have been used to examine the formation of ions m/z 117, 129, 131, 132, 145, 159, 171, 185 and 201 in the spectrum of the TMS ester of decanoic acid. Mechanisms of breakdown of one ion to another have been proposed. Similarities and differences in ion formation between spectra of TMS esters and methyl esters have been examined. It has been shown that ion m/z 132 is produced by the McLafferty rearrangement and that ion m/z 117 is formed from it by loss of a silyl methyl group. Ion m/z 145 is formed by hydrogen transfer from C-5, C-6 or C-7 to the carbonyl oxygen and γ-cleavage. Ion m/z 129 is formed from ion m/z 145 by loss of the previously transferred hydrogen and a silyl methyl group. A mechanism of formation of ions m/z 115, 129, 143 and 157, which contained only one silyl methyl group, observed in the mass spectrum of the TMS ether of decanol, has been proposed. Ions in spectra of the derivatives can be used to locate the position of deuterium, or other substituents, at a number of the carbons of decanoic acid or decanol.     

Selective hydrogenation of fatty acids and methyl esters of fatty acids to obtain fatty alcohols–a review

In this paper, a review is presented of the evolution of different catalytic systems and operating conditions used in the selective hydrogenation of acids and esters of fatty acids to obtain fatty alcohols, which have broad industrial applications in the oleochemical industry. In addition, the current status of the different technologies used industrially (Lurgi, Davy and Henkel) for obtaining fatty alcohols, as well as major global sources of raw materials for the oleochemical industry are put forward. Finally, the reaction mechanisms of the selective hydrogenation process of oleic acid and methyl oleate to obtain the corresponding unsaturated alcohol as well as the new catalysts proposed by researchers are described. © 2016 Society of Chemical Industry     

Preparation of fully deuterated fatty acids by simple method

Lipids - An economical, simple, efficient system of deuterating saturated fatty acids at atmospheric pressure has been developed. Exchange is carried out between fatty acids and deuterium gas over...     

Sulfonated branched chain fatty acids and esters

In continuation of work reported a year ago describing branched chain fatty acids, a series of monosodium methyl 2-sulfo-2-alkylalkanoates [RR'C (SO₃Na) CO₂CH₃] were synthesized. The surface active properties of these compounds were evaluated and compared with the corresponding disodium 2-sulfo-2-alkylalkanoates [RR'C (SO₃Na)CO₂Na]. Alkaline hydrolysis rates show that the sodium methyl esters are stable. Relative to the disodium salts, these compounds exhibit better wetting properties and more stable foams. Presented at the AOCS Meeting, Cincinnati, October 1965. E. Utiliz. Res. Dev. Div., ARS, USDA.     

Ring position in cyclopropene fatty acids and stearic acid desaturation in hen liver

Four cyclopropene fatty acids, having the double bond of the cyclopropene ring at the 8,9, 9,10, 10,11 and 11,12 positions, respectively, were tested as inhibitors of stearic acid desaturation by the desaturase enzyme system of hen liver. The first three were powerful inhibitors, but the last was not. The cyclopropene acids with the 9,10 and 10,11 double bonds were equally strong inhibitors, while the acid with the 8,9 double bond was less effective. To account for the specificity of those cyclopropene fatty acids in which the C9 or C10 carbon atom is included in the cyclopropene ring, it is suggested that the conformation and structure of the CoA derivatives of these acids is such that they can irreversibly occupy the site on the enzyme responsible for 9,10-desaturation.     

Reaction of cyclopropene esters with hydrogenation catalysts

Methyl esters of stereulic and malvalic acids were heated under nitrogen in the presence of various hydrogenation catalysts, and the effect on the cyclopropene moiety was established. Similar tests were conducted with cottonseed oil, which contains glycerides of sterculic and malvalic acids. Palladium catalysts, and some palladium compounds which were tested, readily gave cyclopropene-free products, while nickel and platinum catalysts did not. Palladium catalysts freshly activated with hydrogen were not as active as those freed of adsorbed hydrogen. The catalysts could be reused. Heating cottonseed oil (0.73% cyclopropenes, calculated as trimalvalin) with 0.02% palladium, as a 10% palladium-on-carbon catalyst, gave a cyclopropene-free oil after 2 hr at 150 C. The treated oil was unaltered in appearance, and the noncyclopropene components were unaffected. Heating methyl sterculate with palladium catalyst produced a mixture of unsaturated condensation products and a number of unsaturated monoesters of practically unchanged molecular weight. The palladium treatment was shown to cleave the cyclopropene ring and produce methyl and methylene substituted fatty acid groups. Presented at the AOCS-AACC Joint Meeting, Washington, D.C., April 1968.     

Effects of protected cyclopropene fatty acids on the composition of ruminant milk fat

Unsaturated fatty acids can be protected from ruminal hydrogenation, and, when fed to lactating ruminants, the constituent acids are incorporated into milk triacylglycerols. By this means, it has been possible to reduce the melting point of milk triglycerides and to make softer butter fat. This report shows that, by feeding small amounts of protected cyclopropene fatty acids, one is also able to make harder butter fat.Sterculia foetida seed oil, a rich source of cyclopropene fatty acids, was emulsified with casein and spray dried to yield a free flowing dry powder. When this material was treated with formaldehyde and fed to lactating goats (ca. 1 g cyclopropene fatty acids per day), there were substantial increases in the proportions of stearic acid and decreases in the proportions of oleic acid in milk fat. Similar results were obtained when the formaldehyde-treated supplements were fed to lactating cows (ca. 3 g cyclopropene fatty acids per day). The effect was considerably less apparent when theS. foetida seed oilcasein supplement was not treated with formaldehyde, suggesting that cyclopropene fatty acids are hydrogenated in the rumen as are other unsaturated fatty acids. The effect of feeding protected cyclopropene fatty acids on the stearic: oleic ratio in milk fat is probably due to cyclopropene-mediated inhibition of the mammary desaturase enzymes.     

Fatty acid desaturase systems of hen liver and their inhibition by cyclopropene fatty acids

Hen liver preparations which desaturate stearic acid at the 9,10 position to form oleic acid have been found to desaturate other saturated fatty acids of carbon chain length from 12 to 20 and 22. The 9,10-monoenoic fatty acid of the same chain length as the substrate fatty acid is the major product formed. Minor amounts of the 10,11- and 11, 12-monoenoic acids are also formed. Maximum desaturation occurred with the C₁₄ fatty acid substrate and with the fatty acids C₁₇ and C₁₈, suggesting the presence of at least two desaturating systems. The cyclopropene fatty acids, sterculic and malvalic acids, inhibited the desaturation of all thefatty acids at the 9,10 position but desaturation at the 10,11 and 11, 12 positions was affected only slightly. The effect is not due to inhibition of the primary activating enzyme, the long chain acyl CoA synthetase. Sterculic acid is a more effective inhibitor than either malvalic acid or sterculyl alcohol, probably because these cyclopropene compounds do not block the desaturating site of the enzyme as completely as sterculic acid.     

Observations on the destruction of cyclopropene fatty acids of cottonseed oil on exposure to visible light

The destruction of cyclopropene fatty acids of cottonseed oil on exposure to light from a 500 W tungsten bulb was studied under various conditions in the laboratory. The Halphen test was used to determine the destruction. Visible light exerted a strong catalytic effect and oxygen, at least in traces, was necessary. In 4–12 hr the Halphen response was negative for refined cottonseed oil (0.2–10 ml) sealed in a 50 ml flask at 1 mm Hg without apparent peroxide development. No significant difference was noticed in the peroxide development pattern of the exposed and unexposed samples in the airoven stability test.     

The distribution of cyclopropane and cyclopropene fatty acids in higher plants (Malvaceae)

The occurrence and distribution of cyclopropane and cyclopropene fatty acids has been investigated in seeds, leaves and other tissues of several species of Malvaceae. Sterculic and malvalic acids and their dihydro-analogs were present in all the plant tissues examined, the highest proportions generally being in immature seeds. The cyclic acids were mainly concentrated in the neutral lipids with lesser proportions in phospholipid or glycolipid classes. The occurrence of these acids in all tissues of some species offered the attractive possibility of establishing callus tissue cultures capable of synthesizing cyclopropane and cyclopropene fatty acids and thereby providing a more convenient and reproducible system for biosynthetic studies. Substantial proportions of these cyclic acids were found in callus tissue cultures propagated from twoMalva species.