Sulfoxylated methyl esters as potential components of liquid formulations

Sulfoxylated methyl esters (Φ-MES) are obtained via sulfoxidation of fatty acid methyl esters with SO₂, O₂, and ultraviolet light of appropriate wavelength. These products may be used as co-surfactants with linear alkylbenzene sulfonate and alkyl ether sulfate, either in heavy-duty or in hand dishwashing liquids. Standard hand dishwashing formulations based on Φ-MESC₁₆ are presented and discussed with regard to solubility, viscosity, performance, and skin compatibility. The experimental results obtained indicate that the above-mentioned products can be regarded as potential components for liquid formulations.     

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.     

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.

Performance of straight-chain alkylbenzene sulfonates (LAS) in heavy-duty detergents

The foamability (dishwashing and washing machine) and detergency of LAS in heavy-duty detergents is directly compared with polypropylenė ABS (PPABS) at various mol wt, conen, water hardnesses and temp. In every case a peak in performance is obtained in the C₁₁ to C₁₇ side chain range. The peak is shifted to lower mol wt as water hardness is increased, especially at low detergent conen. LAS opt performance is generally equal to PPABS, except in dishwashing foam in soft water. The LAS peaks, however, are shifted to ca. one carbon lower mol wt than the PPABS. Therefore, best over-all performance is obtained for LAS whose average mol wt corresponds to a 12.5 carbon side chain, whereas PPABS is best with an average 13.5 carbon side chain. Dishwashing foamability is markedly different for the different isomers contained in LAS. When the phenyl group it attached to the middle of the alkyl chain, surprisingly high results are obtained. This dishwashing difference is great enough to be noticeable when the isomer distribution changes in whole products made using different alkylation catalysts. Detergency and washing machine foam are not affected enough to see differences between whole alkylates. LAS solubility is greater than PPABS and is influenced by isomer distribution. Present address: W. Reg. Res. Lab., USDA, Albany, Calif.     

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.     

Dishwashing performance of mixed palm stearin sulfonated methyl esters—Nonylphenol ethoxylate alcohol

The dishwashing performance of sodium salts of α-sulfonated methyl esters derived from palm stearin (α-SMEPS) and nonylphenol ethoxylate alcohol (NPEO) in mixed micelle systems was evaluated as a function of weight ratio at different water hardness values (5.12, 51.2, and 512.0 ppm CaCO₃) and temperatures (20, 30, and 45°C). Manipulating several parameters, such as weight ratios in α-SMEPS and NPEO mixtures, washing temperature, and water hardness, can enhance detergency performance. In comparison, detergency efficiency of the mixtures increased as follows: α-SMEPS/NPEO 400<α-SMEPS/NPEO 120<α-SMEPS/NPEO 95.     

Alpha olefin sulfonates from a commercial SO3-Air reactor

Alpha olefin sulfonate (AOS) can be made by SO₃-air sulfonation of straight chain alpha olefins followed by saponification of the neutralized product. The sulfonation step forms unsaturated sulfonic acids, sultones and sultone sulfonic acids. Hydrolysis of the various sultones yields a mixture of unsaturated and hydroxy sulfonates. Sulfonation of commercial mixtures of straight chain alpha olefins in a large-scale SO₃ falling film unit has given AOS of 1.5–3.0% oil based on active content and tristimulus color of about 40% saturation (2% solution) which is readily bleachable with 1–3% NaOCl to about 10–15% saturation. Performance of AOS made from C₁₅−C₁₈ alpha olefin is comparable to that of the high-foaming C₁₁−C₁₄ LAS in both detergency and dishwashing foam. It is superior to similar products made from internal straight chain olefins. The product shows a low order of toxicity and biodegrad-ability slightly better than that of LAS. A C₁₅−C₁₆ AOS blend is especially attractive in liquid detergent formulations. Presented at the AOCS Meeting, Los Angeles, April 1966.     

Methyl Ester Sulfonate: A High-Performance Surfactant Capable of Reducing Builders Dosage in Detergents

The detergency performance of α-sulfo fatty-methyl ester sulfonate (α-MES) under different water hardness conditions was compared against the dominant workhorse in Home Care products, linear alkylbenzene sulfonate (LAS). Results demonstrate that α-MES has a higher soil removal index and its detergency performance is not drastically affected by water hardness, compared to that of LAS. The addition of α-MES to LAS also shows an improved cleaning performance and better water hardness resistance, due to the structural characteristics of α-MES, which allow the molecules to be relatively insensitive toward polyvalent ions such as Ca²⁺ and Mg²⁺. The washing performance of α-MES, α-MES/LAS, and LAS with different builders at various dosages was studied, and the results indicated that the dosage of builders in the detergent product could be reduced up to 33% with the application of α-MES, while the detergency is not sacrificed.     

Summary of the technology for the manufacture of higher alpha-sulfo fatty acid esters

Interest in α-sulfonated higher molecular weight (up to C₂₀) fatty esters has increased in recent years in the surfactant industry due to the advent of economical sulfonation processes and methyl esters of fatty acids. In this paper, the authors present a review of the chemistry of the sulfonation of fatty esters and the two-step mechanism leading to α-sulfonation. Laboratory and pilot plant scale preparation of long chain fatty acid α-sulfoesters with vaporized SO₃ without the use of solvents are also summarized. Work on the falling film equipment with hydrogenated methyl tallowate with vaporized SO₃ is described along with procedures for neutralization and bleaching. Analytical methods for defining the α-sulfonates are discussed. A larger scale unit to continuously manufacture α-sulfo fatty esters from long chain fatty acid is described. A review of the commercially available continuous processes for sulfonation of the fatty acid esters with vaporized sulfur-trioxide have also been included. The properties of the salts of α-sulfo fatty esters including the hydrolytic stability, aqueous solubility, lime soap dispersing ability, and biological properties have been tabulated. Uses of these surfactant range α-sulfo esters are included in this discussion. Presented at the AOCS Meeting, New Orleans, April 1976.     

Effect of carbon chain and phenyl isomer distribution on use properties of linear alkylbenzene sulfonate: A comparison of ‘high’ and ‘low’ 2-phenyl LAS homologs

Phenyl isomer distributions, within current commercial limits of HF and A1C13 linear alkylbenzene sulfonates (LAS), have little effect on dishwashing performance in light-duty liquids (LDL), detergency performance in heavy-duty powders (HDP), and interfacial tension value. The most important factor in determining performance differences among commercial LAS samples is carbon chain homolog distribution. Both HF and A1C1₃ LAS perform equally well and can be used interchangeably in high-performance products. The optimum for foam stability in light-duty liquids shifts towards shorter alkyl chain length as water hardness increases. At 0 ppm water hardness the optimum occurs at C₁₃: at 50–150 ppm the optimum moves to C₁₁ and C₁₂; and above 150 ppm the optimum shifts to include C₁₀, C₁₁ and C,₁₂. The detergency performance optimum range in a phosphate built heavy-duty powder at 50 and 150 ppm water hardness includes the C₁₂, C₁₃ and C₁₄ alkyl chain lengths. In a nonphosphate built powder the optimum is similar at 50 ppm hardness to that of a phosphate built powder, but shifts at 150 ppm hardness to include C₁₁, C₁₂ and C₁₃.     

Sulfoxidation of fatty acid methyl esters: Conversion and selectivity

In this work several batch sulfoxidation reactions of different fatty acid methyl esters, having chain lengths of C12 to C18, in the presence of SO₂, O₂, and ultraviolet light of 253 nm have been carried out. The average reaction conversion for each methyl ester has been calculated and the selectivity determined by liquid chromatography. The results indicate that conversion increases dramatically with the increase of carbon chain length, whereas selectivity to monosulfonate seems to increase slightly as the chain length increases.     

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.     

Ultimate biodegradation studies of α-olefin sulfonates

Single carbon cut α-olefin sulfonates (AOS) having 12, 14, 16 and 18 carbon chain lengths and several of their blends were prepared from high-quality α-olefins by continuous SO₃ sulfonation in a laboratory falling film reactor. The ultimate biodegradability of these products was studied using a modified shake flask procedure with CO₂ evolution as the major biodegradability criterion. For comparison, commercial samples of a modified Ziegler-based AOS, linear alkylbenzene sulfonates (LAS), and an alcohol ethoxysulfate (AEOS) were included. The results showed the AOS products bio-degraded to CO₂ more completely than LAS and slightly less extensively than AEOS. CO₂ evolution decreased slightly in amount and rate as AOS carbon chain length increased in the C₁₄ to C₁₈ range. Presented at the AOCS meeting, May 1977, New York City.     

Direct conversion of lipid components to their fatty acid methyl esters

Summary Methyl esters were prepared from cholesteryl esters, phospholipids, and glycerides in substantially quantitative yields by methanolysis with large excess of sodium or potassium methoxide in absolute methanol. A silicic acid chromatographic adsorption column technique was described, which was effective in separating methyl esters from unsaponifiables such as sterols, pigments, etc., and free acids. Conditions for complete methanolysis of glyceride fats and oils requiring only 5 min. of reflux time were described. Quantitative conversion of fatty acids to methyl esters was accomplished by direct esterification with absolute methanol containing 4% HCL or H₂SO₄ and by methylation with diazomethane. Presented at the 50th Meeting, American Oil Chemists’ Society, New Orleans, La., April 20–22, 1959. Eastern Utilization Research and Development Division, Agricultural Research Service, U. S. Department of Agriculture.     

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.     

Molecular species of wax esters in jaw fat of atlantic bottlenose dolphin,Tursiops truncatus

The jaw fat of the Atlantic bottlenose dolphin (Tursiops truncatus) contains unusual wax esters which can be separated into short chain (<C₂₄) and long chain (>C₂₄) fractions by thin layer chromatography. The short chain wax esters (28 wt. %) have been characterized as a 72∶24∶4 mixture of isovaleroyl, isobutoryl, and 2-methylbutyrol, esters of C₁₄–C₁₈ n- and iso-alcohols. The intact <C₂₄ esters have been resolved into individual molecular species by gas liquid chromatography on open-tubular polyester columns. The long chain wax esters (12 wt. %) contain C₁₀–C₂₂ n- and iso-acids esterified to the same C₁₄–C₁₈ n- and iso-alcohols. Gas liquid chromatography of the intact, hydrogenated >C₂₄ esters on a short JXR column has characterized them according to carbon number and the number of methyl branches they contain.     

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.     

Linear alkylbenzene sulfonates in the prevention of vagrant dye pick-up on polyester textile fabric during laundering

The unwanted pick-up of low levels of vagrant dyes during washing of textile fabrics can be a significant contributor to long-term polyester appearance degradation. Fabric appearance loss from pick-up of small quantities of a standard yellow dye are measured on both optically brightened and unbrightened polyester. Linear alkylbenzene sulfonate (LAS) surfactant micelles act as effective dye scavengers, reducing the level of dye pick-up by the fabric substantially. The efficacy of LAS as a dye scavenger is quantified as a function of alkyl chain length and use concentration. Dye scavenging ability per unit weight of LAS increases with increasing molecular weight and decreasing critical micelle concentration (cmc). Dye scavenging of up to 80% of the transferable dye is achieved at high LAS concentrations. Results with C₉, C₁₁, C₁₃ and C₁₅ single homolog alkyl chain lengths, and with several mixed chain length blends are presented. Presented at the AOCS symposium on “Surfactants in Textiles,” New Orleans, May 1981.     

Sodium salts of alkyl esters ofa-sulfo fatty acids. Wetting,lime soap dispersion,and related properties

A series of esters of the general formula RCH(SO₃Na)-CO₂R′ of 14–19 carbon atoms prepared by the α-sulfonation of propionic, butyric, pelargonic, lauric, myristic, palmitie, and stearic acids and esterification with normal primary alcohols were compared for critical micelle concentration, surface and interfacial tension, Ca⁺⁺ stability, wetting properties, foam height, detergency, and lime soap dispersing properties. Comparison of position isomers showed that as the hydrophilic portion moved from the center toward either end, cmc and wetting efficiency decreased, surface and interfacial tension increased, and Ca⁺⁺ stability and lime soap dispersing properties improved. A coconut oil fatty acid forerun sulfonated with SO₃ vapor and esterified with 2-ethylhexanol gave a product with useful wetting properties in soft and hard water. Presented at the fall meeting, American Oil Chemists' Society, Chicago, October 30–November 1, 1961. Eastern Utilization Research and Development Division, Agricultural Research Service, U. S. Department of Agriculture.     

Synthesis and Characterization of New Biodiesels Derived From Oils of Plants Growing in Northern Wisconsin and Minnesota

We report on the preparation and selected properties of some new biodiesels which we synthesized from oils of plants growing in Northern Wisconsin and Minnesota. The composition and the low-temperature properties such as crystallization onset T _c and end of melting T _m investigated with the help of differential scanning calorimetry are presented. Some of these biodiesels exhibited remarkably good low-temperature characteristics. In order to further improve these properties, we use a variety of alcohols during the transesterification process, including isopropyl, 2-butyl, and isoamyl alcohols. Using several parameters such as oil content and crystallization onset temperature T _c, plant species that appear most promising have been identified, among those highbush cranberry (T _c ≈ −31 °C for its methyl esters, T _c ≈ −41 °C for its 2-butyl esters), dotted horsemint (T _c ≈ −17 °C for its methyl esters, T _c ≈ −40 °C for its 2-butyl esters), and American hazelnut (T _c ≈ −19 °C for its methyl esters, T _c  ≈ −30 °C for its 2-butyl esters).