Analysis of the dark-colored impurities in sulfonated fatty acid methyl ester

A fractionally distilled C₁₄−C₁₆ fatty acid methyl ester, derived from palm oil, was sulfonated with gaseous SO₃ in a falling film reactor to form an α-sulfo fatty acid methyl ester (α-SF; unbleached and unneutralized form). The included dark-colored impurities were then separated from α-SF as a diethyl ether-insoluble matter. After purification by thin-layer chromatography, the colored species were analyzed by ion-exchange chromatography, gel-permeation chromatography, and nuclear magnetic resonance spectrometry. These data suggested that the colored species were polysulfonated compounds with conjugated double bonds. Minor components in the raw fatty acid methyl ester, found by gas chromatography/mass spectrometry, were spiked into the purified methyl palmitate and then sulfonated. The unsaturated methyl ester and hydroxy ester showed the worst color results. The methyl oleate and methyl 12-hydroxystearate were then sulfonated and analyzed. Deep black products were obtained, which showed the same properties as the colored species in α-SF. It was concluded that low levels of unsaturated fatty acid methyl esters and hydroxy esters in the fatty acid methyl ester are the main causes of the coloring.     

Soap and related products: Palm and lauric oil

There are three main methods for producing soap: direct saponification of fats and oils, neutralization of fatty acids and saponification of fatty acid methyl esters. Our unique process of soapmaking, based on the methyl ester saponification method, is described here. By this process, high-quality toilet soaps can be produced from palm stearin and palm kernel oil as well as tallow and coconut oil. A new sulfonation process was developed to produce high-quality α-SFMe (α-sulfo fatty acid methyl ester) from palm stearin as the starting material. Quality and performance of α-SFMe bear comparison with those of LAS, AES, AS or AOS. Thus α-SFMe is a promising surfactant for detergents and will contribute to expanding the use of palm oil in the near future.     

Alpha sulfo fatty esters in biologically soft detergent formulations

Salts of α-sulfo tallow and coconut esters were subjected to river die-away, activated sludge and Warburg tests, and results show these derivatives to be biologically soft detergents with disappearance curves approximating those of the fatty alcohol sulfates. Selection of the proper fatty acid starting material, alcohol of esterification, and alkali for neutralization provides for a high degree of flexibility in tailor-making biologically soft surface active agents for a wide range of applications. Selected compounds have been found which exhibit remarkable foaming, lime soap dispersing, fabric and hard surface detergency, wetting and related surface-active properties. These properties allow the formulation of a variety of synthetic and soap-synthetic combinations. Primary emphasis is given to the presentation of data on surfactant formulation application studies. Salts of short chain alkyl esters of α-sulfo tallow acid are ideally suited for “combo” soap bar and built heavy-duty detergent applications. Salts of short chain alkyl esters of selected coconut fatty acids are uniquely suitable for light duty liquids, cosmetic and related surfactant applications. An improved process for the manufacture of these sulfo esters has been developed which produces high yield, high purity and light colored products, and which should provide for their acceptance on a large scale in the detergent field. Presented at the 37th Annual AOCS Meeting, Minneapolis, Minn. Oct. 1, 1963.     

Soap-based detergent formulations: IX. α-sulfo fatty alkanolamides as lime soap dispersing agents

α-Sulfo fatty alkanolamides were prepared by sodium methylate catalyzed reactions of methyl α-sulfo fatty esters with alkanolamines, such as ethanolamine, N-methyl-2-hydroxyethylamine, diethanolamine, 3-hydroxypropylamine, 2-hydroxypropylamine, and diglycolamine. Pure compounds, such as α-sulfo palmitamides and stearamides, as well as the α-sulfo tallow amides, were prepared and evaluated as surface-active agents. The α-sulfo fatty alkanolamides were found to have excellent stability to alkali. Their stability to acid ranged from excellent in the case of α-sulfo diglycolamides to poor in the case of α-sulfo diethanolamides. Poor stability to acid was related to ease of conversion to ester-amines. Washing tests on standard soil cloths showed that the compounds were good detergents by themselves and were also effective in combination with soap and silicates. Their lime soap dispersant requirements ranged from 7–10. Presented at the AOCS Meeting, September 1973, Chicago. ARS, USDA.     

Soap-based detergent formulations: XV. Amino esters of α-sulfo fatty acids

Amphoteric surfactants were prepared either by direct esterification of α-sulfo fatty acids with various alkanolamines or by rearrangement of the corresponding alkanolamides of the α-sulfo fatty acids to the amino esters with the aid of aqueous hydrochloric acid. The α-sulfo fatty acid monoesters of diethanolamine could be prepared only via the rearrangement method. The amino esters in the C₁₆−C₁₈ range possessed limited water solubility whereas α-sulfolaurate esters were soluble at room temperature. The amino esters were found to be stable to acid hydrolysis; however, they were generally not stable to alkali, by which they were either hydrolyzed or rearranged to the corresponding amide. Only the esters of isopropanolamine and diglycolamine were stable to alkali. Surface active properties of the esters were determined. The lime soap dispersant requirements of the compounds were slightly poorer than those of the corresponding amides. The compounds were good cotton detergents by themselves as well as in combination with soap and a silicate builder. The overall surface active properties of the amino esters were greatly inferior to those of the sulfobetaines previously reported. This indicates that an effective amphoteric lime soap dispersant should have its anionic group located at the very end of the molecule and the cationic group somewhat farther away, instead of the reverse. Presented at the AOCS Meeting, Philadelphia, September 1974.     

Hexitol and sucrose esters of α-sulfo fatty acids

Use of the α-sulfo acid, the acid chloride and the methyl ester was explored in the preparation of mannitol, sorbitol and sucrose esters of α-sulfopalmitic and α-sulfostearic acids. The products were difficult to purify because of solubilization of reactants. The α-sulfo esters are more soluble and more resistant to hydrolysis than hexitol and sucrose palmitates and stearates. Presented at the AOCS Meeting, New York, October 1968. ARS, USDA.     

α-Sulfonated fatty acids and esters: Manufacturing process,properties, and applications

α-Sulfonated fatty acid esters, because of their wide-range of application and biological properties, represent an interesting class of surfactants. A technical method for the preparation of α-sulfonated fatty acid esters is described. By using special reaction conditions it is possible to α-sulfonate saturated fatty esters directly without the use of solvents. The use of gaseous SO₃ gives the product in greater than 97% yield. A process for the bleaching of the α-sulfonated fatty esters has been developed, whereby a product of faultless color is produced without the necessity of further purification or separation techniques. The sulfonation and bleaching processes operate continuously. The process has been tried successfully on a commercial scale using the methyl esters of technical fatty acids. Methods for the preparation of α-sulfonated fatty acids are given. The chemical, technical, and biological properties of the α-sulfonated fatty acids and their esters are discussed. α-Sulfonated fatty esters possess good washing and foaming properties, have good biological degradability, possess good skin compatibility and low acute toxicity. They can be considered as surfactant components for phosphate-free or low-phosphate detergents. α-Sulfonated fatty acids and esters also possess other favorable technical properties which allow them to be used in cosmetics, as auxiliary agents in the production of fibers, plastics, and rubber, and in leather manufacture.     

α-Sulfonated fatty acid esters: I. Structural effects of sodium α-sulfonated fatty acid higher alcohol esters on surface-active properties and emulsification ability

The surface-active properties and emulsification ability of sodium α-sulfonated fatty acid esters, C_mH_2m+1CH-(SO₃Na)COOC_nH_2n+1, were studied as a function of the hydrophobic alkyl chainlength in the fatty acid (m=8−16) and the alcohol (n=8−18). As a result, it was discovered that sodium α-sulfonated fatty acid esters have a structural effect on the Krafft point different from that of amphiphiles with short alkyl chains. Moreover, some of the α-sulfonated fatty acid esters have quite low interfacial tensions, as well as non-foaming properties, which depend upon the total (m+n) number of carbon atoms in the alkyl chains.     

Performance of Φ-Sulfo Fatty Methyl Ester Sulfonate Versus Linear Alkylbenzene Sulfonate,Secondary Alkane Sulfonate and α-Sulfo Fatty Methyl Ester Sulfonate

Sulfoxidation of fatty acid methyl esters with SO_2, O₂ and ultraviolet light of appropriate wavelength, has led to the synthesis of methyl esters sulfonates or sulfoxylates, known as Φ-MES, because of the possible random position of SO₃ group in the alkyl chain. Aqueous solutions based on the sulfoxylated methyl ester of palmitic acid (Φ-MES C16) have been studied and compared to the leading types of surfactants used today: linear alkylbenzene sulfonate (LAS) secondary alkane sulfonate (SAS) and α-sulfo fatty methyl ester sulfonate (α-MES) with regard to solubility, performance and skin compatibility. The experimental results obtained indicate that Φ-MES C16 can be regarded as a potential component of detergent formulations and most likely also of body care products.

Beiträge zur Analytik von Estersulfonaten

Contributions to the Analysis of Sulfonated Esters Several methods for the characterization and determination of α-Sulfo fatty acid methyl esters are described. The sulfonated ester is detected by thin layer chromatography on silica gel plates with tetrahydrofuran + acetone (1+9 v/v) as solvent and with pinacryptol yellow/UV-light for the visualization. Pyrolysis-gas liquid chromatogrphy with heating a sample/P₂O₅-mixture at 400°C yields the chain length distribution of the fatty acids initially used. The amount of an α-sulfo fatty acid ester is determined by extraction with i-propanol and by two-phase titration (Epton). the saponification product of the sulfonated ester is in the i-propanol insoluble part. For a quantitative determination of the α-sulfo fatty acid methyl ester by thin layer chromatography the sample solution is directly applied to the thin layer plate. A range of defined volumes, with increasing amounts of the sample are applied to the plate by means of an applicator. The chromatograms are visually compared. Ion chromatogrphy with the mobile phase, NH₃/Acetonitrile separates the α-sulfo fatty acid esters by chain-length. Determination is achieved by standards with defined chain-length.     

Microaerophilic biodegradation of tallow-based anionic detergents in river water

Nine anionic detergents from five general classes (alcohol sulfates, ether alcohol sulfates, sulfated alkanolamides, α-sulfo esters and alkylbenzenesul-fonates) were rapidly screened for biodegradability under aerobic and microaerophilic conditions in river water at 25 and 35 C. In decreasing order, the ease of biodegradation under microaerophilic conditions at 35 C was as follows: alcohol sulfates, sulfated alkanolamides, α-sulfo fatty acid esters and ether alcohol sulfates. Linear alkylbenzenesulfonate did not degrade. Presented at the AOCS Meeting, New Orleans, April 1970.     

Performance of sulfoxylated fatty acid methyl esters

Sulfoxidation of fatty acid methyl esters with SO₂, O₂, and ultraviolet light of appropriate wavelength has led to the synthesis of methyl esters sulfonates or sulfoxylates known as Φ-MES because of the possible random position of SO₃ group in the alkyl chain. This work describes experimental measurements of physical properties such as solubility and viscosity of sodium Φ-MES water solutions. Amphipathic properties such as surface tension, critical micelle concentration, wetting and foaming powers were measured as well and compared to linear alkylbenzene sodium sulfonate (LAS). Finally, stability to water hardness, dishwashing test, and detergency performance were evaluated. Expectedly, these products may be used as LAS partners either in heavy-duty powders or in hand dishwashing liquids. Experimental results on Φ-MES of varying carbon number indicate that C₁₆ is the optimal carbon chain length.     

The course of biodegradation of anionic detergents by analyses for carbon,methylene blue active substance and sulfate ion

Tallow alcohol sulfates, ether alcohol sulfates and esters of α-sulfo tallow fatty acids were degraded aerobically by sewage microorganisms in a system in which detergent was the sole source of C. Biodegradation was followed by loss of C and methylene blue active substance (MBAS) and formation of SO ₄ ⁻⁻ . Tallow alcohol sulfates were rapidly and completely degraded; ether alcohol sulfates not quite as readily. Reduction in MBAS was rapid for the α-sulfo esters but loss of C and SO ₄ ⁻⁻ formation was incomplete, possibly because of the intermediate formation of a resistant sulfosuccinate. Sodiump-(1-methylundecyl) benzenesulfonate (LAS) was the reference standard. Presented at the AOCS Meeting, San Francisco, April 1969.     

Coloration Process in the Sulfonation of Fatty Acid Methyl Ester with Sulfur Trioxide

Fatty acid methyl ester sulfonate (MES), an anionic surfactant suitable as a laundry detergent, is produced commercially by the direct sulfonation of fatty acid methyl ester (ME) with SO₃. However, intense coloration occurs during the sulfonation process. The sulfonation of ME was performed through the addition of SO₃ (SO₃/ME molar ratio = 0.8–1.2) for 1–4 h and subsequent aging for 1 h at 80 °C. Even when the amount of unsaturated bonds in ME was reduced to give an iodine value (IV) of less than 0.01, coloration occurred during the sulfonation, making the unbleached product unsuitable for commercial use. The formation of olefinic units and SO₂ was observed during the reaction, and the color of the reaction mixture was strongly correlated with their amounts. Further analysis confirmed that equimolar amounts of the olefinic unit and SO₂ were formed, and the rate profiles of the formation of MES and SO₂ agreed well with each other. From these observations, we concluded that the coloration of the reaction mixture was caused by oxidation of the alkyl chain with SO₃ during the liberation of SO₃ from the 1:2 adduct of ME and SO₃, a key intermediate in the sulfonation process.     

Polyhydric alcohol esters of α-sulfo fatty acids

Direct esterification of α-sulfopalmitic and α-sulfostearic acids with excess ethylene glycol, glycerol, pentaerythritol and 2-methoxyethanol was carried out in carbon tetrachloride to give products containing essentially monoesters. Surface active properties of these compounds were measured with emphasis on washing ability in combination with soap. The detergency of these esters was compared with those of hexitol and sucrose α-sulfo fatty acid esters. Although the esters had moderate lime soap dispersing ability, their detergency showed synergism when combined with soap. Deceased. East. Market. Nutr. Res. Div., ARS, USDA.     

Synthesis, characterization, and surface properties of sulfoxylated methyl esters

Sulfoxidation of fatty methyl esters with SO₂, O₂, and ultraviolet light of appropriate wavelength has led to a synthesis of sodium methyl ester sulfonates known as Φ-MES. The designation of Φ refers to the random positioning of SO₃ in the alkyl chain. This investigation describes for the first time the operating conditions necessary to produce these new anionic surfactants as well as the analytical methods used in their isolation, analysis, identification. Some surface properties are discussed as well.     

Benzyl,cyclohexyl, and phenyl esters ofalpha-sulfo fatty acids

Sodium salts of benzyl, cyclohexyl, and phenyl esters of α-sulfopelargonic, α-sulfopalmitic, and α-sulfostearic acids were prepared by reaction of the α-sulfo acid with excess of the alcohol or phenol, in the presence of methylene chloride, carbon tetrachloride, benzene, or toluene. Synthesis from the acid chloride of the α-sulfo acid gave lower yields of a less pure product. Melting point, surface and interfacial tension, critical micelle concentration, rate of hydrolysis and wetting, foaming and detergent properties were measured. The ring esters have properties similar to the corresponding propyl, butyl, or amyl esters. Presented at the AOCS Meeting, New Orleans, May 1967. E. Util. Res. Dev. Div., ARS, USDA.     

Analysis of α-branched fatty acids by gas chromatography and mass spectrometry

Gas liquid chromatography and mass spectrometry were utilized in combination to identify isomeric α-branched chain fatty acid methyl esters. In a given isomeric series equivalent chain length, values decreased with increase in the number and size of α-alkyl substituents. Mass spectra of the α-monoalkyl derivatives are characterized by prominent McLafferty rearrangement ion peaks, whereas those of the α,α-dialkyl isomers contain the former ions plus an α-cleavage ion. Presented at the AOCS Meeting, Chicago, September 1973.     

Determination of physicochemical properties of some fatty acid methyl esters by gas liquid chromatography

Physicochemical data such as vapor pressures (p⁰), heats of vaporization (ΔH_v), activity coefficents at infinite dilution (γ^∞) and excess partial molar entropy (ΔS _e ⁰ ) are considered important for conducting unit processes and designing reactor equipment. Scanty information regarding such data is available in the literature for the higher fatty acid methyl esters. The objective of this research was to determine the physicochemical properties of higher fatty acid methyl esters (C₁₁–C₂₃) by a gas-liquid chromatographic technique with SE-30 and diethylene glycol adipate as stationary phases. Correlations between carbon numbers and various thermodynamic properties have indicated definite trends, which could be useful in predicting the properties of unknown fatty acid methyl esters. The data generated may be useful to chemical engineers in the construction of storage tanks, solvent extractors and distillation columns. IICT communication no. 2993.     

Long chain alkanesulfonates and 1-hydroxy-2-alkanesulfonates: Structure and property relations

Even chain sodium alkanesulfonates from the Strecker reaction, odd chain sodium alkanesulfonates from the alkaline decarboxylation of α-sulfo acids, and sodium 1-hydroxy-2-alkanesulfonates from the reduction of esters of α-sulfo acids were compared with respect to Krafft point, critical micelle concentration, detergency and foam height. Sodium alkanesulfonates and crude fusion products from the α-sulfo acids (mixtures of alkanesulfonates of one less carbon atom with a lesser amount of a soap of two less carbon atoms) are more soluble and have better detergent and foaming properties. Sodium 1-hydroxy-2-alkanesulfonates resemble monosodium salts of α-sulfo acids. Alkanesulfonic acids and 1-hydroxy-2-alkane-sulfonic acids obtained from the sodium salts by ion exchange have lower Krafft points and are more readily soluble. The critical micelle concentrations of 1-hydroxy-2-alkanesulfonic acids and α-sulfo acids are nearly the same and about equal to those of alkanesulfonic acids of one less carbon atom. Presented at the AOCS meeting in Toronto, Canada, 1962. A laboratory of the E. Utiliz. Res. & Dev. Div., ARS, U.S.D.A.