Preparation and surfactant properties of diglycerol esters of fatty acids

Fatty acid mono- and diesters of diglycerol constitute the major portion of commercial polyglycerol esters; hence, their composition influences the performance of the latter as emulsifiers. The correlation of structure of the fatty acids in the mono- and diesters with surfactant properties is of interest. Linear diglycerol was isolated from polymerized glycerol by acetonation, fractional distillation and regeneration. Diglycerol mono- and diesters of undecenoic, lauric, stearic, oleic and ricinoleic acids were prepared by reacting diglycerol and fatty acids in a refluxing mixture of acetonitrile-tetrahydrofuran (75:25) in the presence of p-toluenesulfonic acid and molecular sieves. Mono- and diesters were separated by silica gel column chromatography, and their purities were ascertained by thin layer chromatography and determination of saponification value. The structures were confirmed by periodic acid oxidation, chemical-ionization mass spectrometry and 13 C-NMR spectroscopy. Surfactant properties of the esters were determined. Monoesters showed higher ability in surface tension reduction, emulsification and foaming than the diesters. Short-chain fatty acid esters showed better surfactant properties than the long-chain fatty acid esters. The presence of a central double bond in the lipophilic part of the monoesters reduced emulsion stability. The presence of a hydroxy group in acyl chain retarded foaming and surface tension reducing power.     

Polyglycerol Esters

When glycerol is heated with an alkaline catalyst to over 230 C, water is evolved and polymerization occurs to form a whole family of polyglycerols ranging from diglycerol with 3 hydroxy groups, to triacontaglycerol with 32 hydroxy groups. The carboxylic acid esters of polyglycerols prepared by direct esterification or by interchange, may be solid or liquid; saturated or unsaturated; aliphatic or aromatic; mono, di- or polycarboxylic acid esters; mono-, di-, or polyesters of the polyglycerol; single or mixed acid esters; high or low molecular weight; water or oil soluble; and with an HLB from about 4 to about 13. Polyglycerol esters find utility in a wide variety of food products including beverages, desserts, topping and baked goods. They are thermally stable and find application in several industrial systems.     

Polyglycerine und Fettsäure-Polyglycerinpartialester (Herstellung,Kennzahlen, DC-Trennung)

Polyglycerols and Partial Fatty Esters of Polyglycerols (Preparation, Chemical Constants, TLC-Separation) Polyglycerols of varying degree of condensation were synthesized by condensation of 99% glycerol and these products were analyzed by TLC. The polyglycerols were directly esterified with 99% capric acid, lauric acid, myristic acid, palmitic acid and stearic acid to the corresponding fatty partial esters of polyglycerols, which were analyzed, together with commercial products, by chemical constants and TLC. Thin-layer chromatography, especially the two-dimensional technique, on boric acid impregnated silicagel 60 precoated plates enabled the separation of fatty partial esters of polyglycerols into a large number of substance classes, which were partly identified by comparison with known synthetic compounds, such as partial esters of palmitic acid with diglycerols and triglycerols. This simple TLC method provides characteristic chromatograms, gives an insight into the complex character of such fatty partial esters of polyglycerols, and enables the identification of these substances which are used as emulsifiers.     

Acetoxyglycerol acetal derivatives of mono- and polyformyloctadecanoate esters: Plasticizers for poly(vinyl chloride)

Methyl and butyl(acetoxyglycerol acetal) esters were prepared from 9(10)-formyloctadecanoate or its dimethyl acetal. Mixtures of acetoxy mono- and diglycerol acetals, plus acetoxy mono-, di-, and triglycerol acetals, were prepared respectively from hydroformylated safflower and linseed methyl esters. The glycerol acetals were characterized with respect to physical, thermal, chromatographic, and spectroscopic properties. Acetoxy-mixed glycerol acetals from safflower and linseed methyl esters were good primary plasticizers for poly(vinyl chloride) (PVC), whereas acetoxyglycerol acetals of hydroformylated methyl and butyl oleate were good secondary PVC plasticizers. As primary plasticizers, the poly(acetoxyglycerol acetal) esters showed less migration, better heat stability, and higher tensile strength than the generally used PVC plasticizer di(2-ethylhexyl) phthalate.     

Structural Analysis of Partial and Total Esters of Glycerol Undecenoate and Diglycerol Undecenoate

The direct esterification reaction between glycerol and undecylenic acid or between diglycerol and undecylenic acid generates all the possible types of glycerol or diglycerol esters. Purification by silica gel chromatography resulted in the isolation of each of these types of ester in a pure form. The molecular structures of the compounds isolated were characterized and identified by mass spectrometry, ¹H NMR, ¹³C NMR and DEPT‐135. We then studied the composition of esters of undecylenic acid formed with glycerol or diglycerol as a function of their reaction conditions, which constitute a highly complex system. We purified undecylenic acid esters from each polyol family to allow the structural identification of each ester of glycerol and each ester of diglycerol with undecylenic acid. We found that the polarity of these non‐ionic amphiphilic esters directly affected their affinity for organic and inorganic solvents and that these esters behaved very differently from anionic amphiphilic molecules, such as undecylenic acid.     

Quality control of rapeseed oil methyl esters by determination of acyl conversion

A simple procedure for the evaluation of vegetable oil conversion to methyl esters of fatty acids has been developed. These methyl esters, prepared by the transesterification of vegetable oil with methanol, are used as alternative fuel for diesel engines. A method of gas-liquid chromatography (GLC) on packed columns is used to determine the conversion of acyls bound in acylglycerols to methyl esters. This procedure is based on comparison of the peak areas of methyl esters in fuel samples before and after reaction with an effective transesterification reagent, which will transform unreacted acylglycerols to methyl esters. A correlation between the bound glycerol content, determined by the thin-layer chromatography/flame-ionization detector method, and the acyl conversion, determined by GLC, is given. In acyl conversions to methyl esters over 96.0%, the bound glycerol content is less than 0.25% by weight.     

Fatty acid composition of individual plasma steryl esters in phytosterolemia and xanthomatosis

The bulk of the plasma plant sterol in phytosterolemia occurs in the esterified form and is carried mostly in the low and high density lipoproteins. We have determined the fatty acid composition of the individual plasma steryl esters from a newly discovered subject with phytosterolemia and xanthomatosis. For this purpose the intact steryl esters were subject to high temperature gas liquid chromatography (GLC) on a polar capillary column, which separated the major esters on the basis of molecular weight and degree of unsaturation of the fatty acids. The saturated and unsaturated sterols esterified to saturated, monoenoic, dienoic and tetraenoic fatty acids were identified by GLC analysis of the sterol moieties of the corresponding AgNO₃-TLC fractions of the steryl esters. The GLC results were confirmed by reversed phase high performance liquid chromatography combined with mass spectrometry via direct liquid inlet interface. It was found that, in general, each fatty acid was esterified to the same complement of sterols, and that the esterified sterols possessed a composition comparable to that of the free plasma sterols, which was comprised of about 75% cholesterol, 6% campesterol, 4% 22,23-dihydrobrassicasterol and 15% β-sitosterol. The fatty acid composition of the steryl esters differed from that of the 2-position of the plasma phosphatidylcholines, which contained significantly less palmitic and oleic and more linoleic acid. On the basis of these results and a review of the literature it is suggested that the plasma cholesteryl and plant steryl esters in phytosterolemia originate from both synthesis in plasma via the lecithin-cholesterol acyltransferase and synthesis in tissues via the acylCoA-cholesterol acyltransferase.     

Preparation and properties of some polyglycerol esters of short and medium chain length fatty acids

Mono- and diesters of the short and medium chain acids were prepared with polyglycerols and compared with their corresponding mono- and diglycerides. The physical and chemical properties of such partial esters of polyglycerols, particularly with respect to their oil, water and solvent solubility are given. Polyglycerol esters become more hydrophilic as the molecular weight of the polyol increases. Polyglycerol esters become less hydrophilic as the length of the aliphatic chain of the acid used in esterification is increased. Polyglycerol esters of such short and medium chain fatty acids show promise in applications where surface activity and emulsification, solubilization of oil and water systems is desired. Presented at the AOCS Meeting, New York, October 1968.     

Lipid composition of millet (Pennisetum americanum) seeds

The composition of lipids extracted from a sample of millet seeds by each of 8 solvent systems is reported. Lipid components were separated by silicic acid column and thin layer chromatography (TLC) and quantitated by analysis of fatty acid methyl esters by gas liquid chromatography (GLC), with heptadecanoic acid as internal standard. Best results were obtained by extraction with hot water-saturated butanol. Lipids extracted amounted to 7.2% of the seed dry weight and consisted of 85% neutral lipids, 12% phospholipids and 3% glycolipids. Neutral lipids contained mostly (85%) triacylglycerols and small amounts of mono- and diacylglycerols, sterols and free fatty acids. Sterols consisted of campesterol, stigmasterol and 2 unidentified sterols, occurring in the same proportions in free and esterified forms. Ten glycolipid and 10 phospholipid components were separated and characterized. Contrary to previously published observations, lysophosphatidylcholine was the major phospholipid (42%) in millet seeds; smaller amounts of phosphatidylcholine (24%), lysophosphatidylethanolamine (21%) and trace amounts of phosphatidylglycerol, phosphatidic acid, phosphatidylserine and phosphatidylinositol also were present. The major glycolipids were esterified sterol glycoside, sterol glycoside, monogalactosyldiacylglycerol, digalactosyldiacylglycerol and cerebrosides (ceramide monohexosides).     

Cyclopropenoid Fatty Acids in Malagasy baobab: Adansonia grandidieri (Bombacaceae) Seed Oil

Adansonia grandidieri (bombacaceae family) seed oil gives a positive Halphen test. Composition analysis of derivatized fatty acid methyl esters, in presence of silver nitrate in anhydrous methanol, after chromatography fractionation on silicagel column, were made by gas-liquid chromatography (GLC) using a packed DEGS column. Presence of malvalic and sterculic acids were detected. GLC analysis using glass capillary columns coated with Carbowax 20 M and BDS shows that A. grandidieri seed oil contains mainly palmitic (41%), oleic (22%) and linoleic (12%) acids. Cyclopropenic fatty acid concentration was 14% with 6% for malvalic and 8% for sterculic acids. A slight proportion of dihydrosterculic acid (1.5%) was observed. GLC fatty acid methyl esters analysis, without derivatization, on the two glass capillary columns coated with Carbowax 20 M and BDS gave the same results for cyclopropenic acids content.     

The composition of beeswax alkyl esters

The alkyl esters of beeswax, after isolation from the unhydrolyzed wax by preparative layer chromatography (PLC), have been analyzed directly by high temperature GLC using 1.5% OV1 as liquid phase. In two commercial wax samples examined the ester homologues are predominantly even carbon numbered ranging from C₃₆ to C₅₄. The principal alkyl esters are C₄₀, C₄₂, C₄₄, C₄₆ and C₄₈. The GLC analysis of the ester hydrolysis products revealed that the variations in ester chain length are produced by variations in the esterified primary alcohol chain lengths. The esterified fatty acid is chiefly hexadecanoic acid. The esterified fatty acids differ in composition from the free fatty acids which are also present in the wax.     

Japanese Sardine Oil as a Source of 16:3(n-4) and 16:4(n-l) Fatty Acids

Open tubular gas liquid Chromatographic (GLC) analysis of fatty acids in Japanese sardine oil showed the contents of 1.57% hexadecatrienoic acid (16:3) and 2.55% hexadecatetraenoic acid (16:4). Concentrations of 16:3 and 16:4 were carried out through the urea adduct method, argentation thin layer chromatography (TLC) and reversed phase TLC, with the purities of 16:3 and 16:4 samples obtained being both higher than 92%. They were recognized as 16:3(n-4) and 16:4(n-1) by nuclear magnetic resonance analyses of the methyl esters and GLC analyses of the partially hydrazine hydrogenated products and their oxidative ozonolysis products. The structures were supported by the results of gas chromatographic-mass spectrometric analyses of the pyrrolidides. Other isomers of 16:3 and 16:4 have not been detected in the GLC analysis of the methyl esters. These results indicate that sardine oil is useful as a source of these fatty acids.     

Identification and characterization of fully deuterated fatty acids isolated fromScenedesmus obliquus cultured in deuterium oxide

The algaScenedesmus obliquus cultured in deuterated water, synthesized fully deuterated saturated and unsaturated long chain fatty acids. Their methyl esters were purified and their equivalent chain lengths were determined by gas liquid chromatography (GLC). They were characterized by mass spectroscopy, IR and near-IR spectroscopy, and NMR spectroscopy. Hexadeca-3,6-dienoic acid was identified. The fatty acid compositions of the total lipid and of individual lipid classes were measured. The melting point of methyl perdeuteriohexadecanoate was lower than that of its hydrogen counterpart. Methyl esters of perdeuterio fatty acids had shorter retention times in GLC chromatography on polar and nonpolar phases. Presented before ISF-AOCS Congress, Chicago, September 1970.     

O-etherification between glycerol and glycerol monooleate—demonstration of formation of diglycerol monooleate and triglycerol monooleate by fast atom bombardment-mass spectroscopy and 13C nuclear magnetic resonance

To prepare glycerol monooleate, we reacted glycerol with oleic acid in the presence of a K1411 sulfonic acid resin in the H⁺ form. We utilized glycerol monooleate as an emulsifying agent, as it is a nonionic surfactant that is compatible with the initially biphasic reaction medium. If the expected product does not form, small amounts of a highly polar compound are produced. Both diglycerol monooleate and triglycerol monooleate were isolated by preparative chromatography on a silica column (hexane/chloroform/acetone, 25∶50∶50), and were formally identified by fast atom bombardment (FAB)-mass spectroscopy in positive mode. The products were polyglycerol monoesters. The nature of the products was confirmed by the use of different FAB matrices with or without cationization by alkali metals. The structure of the product was then confirmed by ¹³C nuclear magnetic resonance. we can now propose a new method of polyglycerol ester preparation that yields interesting nonionic emulsifying agents.     

Diglycerin und höhere Oligomere des Glycerins als Synthesebausteine

Diglycerol and Higher Oligomers of Glycerol as Components for Synthesis Part 1 of the paper gives a survey on methods for the preparation of diglycerol and higher oligomers of glycerol. The reactions from diallylic ether, from isopropylideneglycerol with epichlorohydrin, and from glycidol with glycerol are reported. For polyglycerol the alkaline catalyzed condensation of glycerol is discussed. Gaschromatograms of DGLC and PGLC from DSW's Rheinberg production site are presented. Part 2 deals with diglycerol reaction products, e. g. the mono-to tetra-fatty acid esters useful as emulsifying agents, a complex ester prepared by the reaction of a fatty acid mixture and a dicarboxylic acid useful as wool wax substitute, an etherification product from epichlorohydrin, diglycoldialdehyde as oxidation product and diglyceroldiformal after condensation with formaldehyde. The production of so-called non-caloric fat-substitutes from protected (isopropylidene derivatives) and unprotected tri- or tetraglycerols is mentioned.     

Composition of the fat extracted from the seeds of theobroma bicolor

The fat fromTheobroma bicolor was analyzed for glyceride content by thin layer chromatography (TLC), and for fatty acid composition and triglyceride (carbon number) composition by gas liquid chromatography (GLC). The fat was then separated into glycerides of different degrees of unsaturation by means of silver nitrate TLC. Then, the bands were examined by GLC before and after conversion to methyl esters. From the results obtained, the distribution of the fatty acids on the individual glycerides was calculated. The fat consisted of 96.5% triglyceride with only 2.5% diglyceride and 1.7% free fatty acid. The major fatty acids present were 42.3% C18:0, 45,2% C18:1, and 6.0% C16:1. Most of the triglycerides were of carbon number 52 (18.0%) and 54 (77.6%). The major triglycerides were 38.6% 1-stearyl-2,3 diolein (SOO), 25.4% 2-oleyl-1,3 distearin (SOS) and 13.8% 1-palmito-2-oleyl-stearin (POS). Only 44.3% of the fat consisted of monounsaturated triglycerides.     

Stereospecific analysis of fatty acid esters of chloropropanediol isolated from fresh goat milk

The fatty acid esters of chloropropanediol isolated from goat milk fat in small quantities were subjected to a stereospecific analysis via phospholipase C and phosphocholine esters as intermediates. Synthetic rac-1-chloro-2,3-dioleoyl-propanediol was prepared by standard methods and was used as a control. The stereospecific analyses were performed following a release of the fatty acids from the primary positions of each chloropropanediol diester with pancreatic lipase. The resulting X-1-chloro-2-acylpropanediols were then converted into the corresponding phosphocholine derivatives by a stepwise reaction with phosphorus oxychloride and choline chloride. The X-1-chloro-2-acyl-3-phosphocholinepropanediols were subjected to hydrolysis with phospholipase C (C. perfringens), which hydrolyzed 50% of the phosphatide within two min and the rest of it in two hr. From previous experience with glycerol esters, it was assumed that the more rapidly hydrolyzed molecules were the sn-1-chloro-2-acyl-propanediol derivatives and the more slowly hydrolyzed ones the sn-2-acyl-3-chloropropanediol derivatives. A hydrolysis with phospholipase A₂ (Crotalus adamanteus) released 50% of the total fatty acid along with the corresponding lyso compound within 10 min, after which there was no further reaction. The hydrolysis products were assayed directly by gas liquid chromatography (GLC) or were isolated by thin layer chromatography (TLC) prior to quantitation by GLC. Both naturally occurring and synthetic chloropropanediol diesters behaved similarly on stereospecific analysis and were therefore concluded to be racemic.     

Chromatographic analysis of sorbitan fatty acid esters

A procedure is described for the separation, identification and quantitative estimation of mono-, di- and tri-fatty acid esters of sorbitol and of its anhydrides. Stearic, palmitic and oleic acid esters of sorbitol, 1,4-sorbitan and isosorbide were synthesized in the laboratory. Lipid classes were separated by liquid partition column chromatography and TLC. The individual mono-and di-fatty acid esters and the polyols were analyzed by GLC as trimethylsilyl ethers. Recoveries of known compounds in mixtures were in a range of 92% to 100%. Presented at the AOCS-AACC Joint Meeting, Washington, D.C., April 1968.     

Gas-liquid chromatography of polar fatty derivatives1.2

The direct separation of fatty amides is achieved using a polyamide. Versamid 900, as the partitioning agent on a support which need not be previously impregnated with strong alkali or acid, procedures usually followed in the GLC separation of highly polar materials. The combination of a neutral support and polar substrate permits the separation of unsubstituted and substituted long chain fatty amides with as many as 24 carbon atoms with good resolution, in a reasonable time, and with good peak symmetry. The observed area responses agree with the wt percentages of standard amide mixtures, indicating that no loss of amides occurs on the column under the conditions employed. The Versamid column has proved useful in the analysis of other polar fatty derivatives. Conjugated dienoic and trienoic acids run as their methyl esters are retarded sufficiently on Versamid 900 so that they may be estimated in the presence of other fatty acids. Mixtures of compounds with varying polarity, such as mono-, diand triacetin, and glycerol, may be separated easily. Hydroxy and normal fatty acid methyl esters give equally summetrical peaks. Presented at the AOCS meeting, Minneapolis, 1963 Technical Paper, No. 259, ADM Co.     

Distribution of cholesteryl esters and other lipid in subcellular fractions of the adrenal gland of the pig

Total lipids from whole pig adrenal glands as well as from their mitochondria, microsomes, liposomes, and cell sap were extracted and fractionated first into neutral lipids and phospholipids. The highest percentage of neutral lipids was found in the cell sap, and the lowest in the microsomal fraction. Neutral lipids were subfractionated into cholesteryl esters, free cholesterol, triglycerides, and free fatty acids. Cholesteryl esters were distributed throughout the liposomes. Free fatty acids represented a substantial part of cell sap lipids, but were present also in the mitochondria, microsomes, and liposomes. Fatty acids of all fractions were analyzed by gas liquid chromatography. Free fatty acids and cholesteryl ester fatty acids from all cellular fractions were similar in composition and were characterized by considerable quantities of linoleic and arachidonic acid. Triglycerides were characterized by an increased percentage of palmitic and a low content of arachidonic acid. Phosphatidyl choline, phosphatidyl ethanolamine, diphosphatidyl glycerol, and sphingomyelin plus phosphatidyl inositol were isolated from the lipids by preparative thin layer chromatography, and their fatty acids analyzed by gas liquid chromatography. Phosphatidyl choline and phosphatidyl ethanolamine from mitochondria, microsomes, and cell sap were very similar in respect of their fatty acid composition. Sphingomyelin plus phosphatidyl inositol was characterized by a high content of C22:2omega6. Diphosphatidyl glycerol was present in mitochondria and in the cell sap.