Melting Points and Viscosities of Fatty Acid Esters that are Potential Targets for Engineered Oilseed

Our previous isolation of branched-chain fatty acid (BCFA) methyl esters from lanolin was improved and scaled up. Also, oleate esters of isopropanol, oleyl alcohol and normal alcohols of 1–12 carbons chain lengths were prepared. Esters were made by interesterification with sodium alcoholates and by esterification with Candida antarctica lipase. It proved easier to obtain pure esters by the enzymatic synthesis. Melting points and viscosities over the range of 0–70 °C were determined in order to better identify potential lubricant targets that might be produced by genetically modified oilseed crops. Isopropyl and butyl oleate have melting points of −33 and −32 °C, respectively and viscosities that range from ~17 cp (0 °C) to ~2.5 cp (70 °C). They should have suitable stability for lubricants. BCFA esters had viscosities similar to their straight chain analogs. Viscosities increased with alcohol chain length and decreased with temperature. The dependence of viscosity on temperature was fit with an equation based on Erying’s rate equation. Some esters with branched acid or branched alcohol moieties, and some oleate esters might be utilized as biolubricants or biofuels on the basis of their melting points and viscosities.     

Synthesis and surface-active properties of trimeric-type anionic surfactants derived from tris(2-aminoethyl)amine

Trimeric-type anionic surfactants (3C_ntaAm, where n is a hydrocarbon chain length of 8, 10, or 12) with three hydrocarbon chains and three carboxylate headgroups were synthesized from tris(2-aminoethyl)amine, and their properties were investigated by surface tension, electrical conductivity, dynamic and static light-scattering, fluorescence of pyrene, and emulsification power techniques. The critical micelle concentrations (CMC) of 3C_ntaAm were 0.00092–0.00834 mmol dm⁻³, and the surface tensions at the CMC were 33.3–39.9 mN m⁻¹. The areas per molecule occupied by 3C₁₀taAm and 3C₁₂taAm were extremely small, showing they were highly compact at the air/water interface. In addition, adsorption or micellization behavior of 3C_ntaAm was estimated by parameters such as pC ₂₀ (the efficiency of surface adsorption), CMC/C ₂₀ (the ease of adsorption relative to the ease of micellization), and ΔG _M ^o (Gibbs energy of micellization). Dynamic and static light-scattering mesurements of 3C_ntaAm showed a hydrodynamic radius of 45–61 nm above the CMC and aggregation numbers of 10–82 at the CMC, respectively. The fluorescence intensity ratio of the first to the third band in the emission spectra of pyrene started to lower from far above the CMC for 3C₈taAm and 3C₁₀taAm, and below the CMC for 3C₁₂taAm. This suggests that loose micelles or premicellar aggregates are formed in solutions. Mixtures of aqueous solutions of 3C_ntaAm and toluene formed oil-in-water-type emulsions, and the stabilizing abilities were in the order of 3C₈taAm>3C₁₀taAm>3C₁₂taAm. The degree of emulsification of 3C₈taAm remained at 69% after 24 h of standing. Thus, 3C_ntaAm exhibited unique properties superior to monomeric or dimeric surfactants that were significantly influenced by their hydrocarbon chain lengths.     

Synthesis and Characterization of Sodium Nonylphenol Ethoxylate(10) Sulfoitaconate Esters

Two sodium nonylphenol ethoxylate(10) sulfoitaconate ester surfactants, namely disodium nonylphenol ethoxylate(10) sulfoitaconate monoester (DNE(10)SIM) and sodium nonylphenol ethoxylate(10) sulfoitaconate diester (SNE(10)SID), were synthesized through the esterification and sulfonation reactions with nonylphenol ethoxylate(10) ester, itaconic acid and sodium sulfite as the raw materials. The chemical structures of the prepared surfactants were confirmed by FTIR and ¹H NMR. The surface tension of the synthesized surfactants was measured at 25 °C and the surface active properties were characterized. The DNE(10)SIM had better surface activity. The CMC was 1.77 × 10⁻⁶ mol L⁻¹ and γ_CMC was 35.45 mN m⁻¹. The CMC and γ_CMC for the SNE(10)SID were 5.42 × 10⁻⁵ mol L⁻¹ and 37.67 mN m⁻¹, respectively. Moreover, the emulsification power of SNE(10)SID was better.     

Novel surfactants for ultralow interfacial tension in a wide range of surfactant concentration and temperature

This work investigates the possibility of injecting dilute aqueous solutions of novel surfactants into the Yibal field (Sultanate of Oman). This was accomplished through an experimental protocol based on the following criteria: (i) compatibility of the surfactants with the high-saline reservoir water (∼200 g/L); (ii) low interfacial tension (IFT) between crude oil and reservoir water (less than 10⁻² mN m⁻¹); and (iii) maintaining the low IFT behaviour during the entire surfactant flooding. Novel surfactants selected in this study consist of a series of ether sulfonates (AES-205, AES-128, AES-506, and 7–58) and an amphoteric surfactant (6–105). These surfactants were found to be compatible with reservoir water up to 0.1% surfactant concentration, whereas 6–105 and 7–58 showed compatibility within the full range of surfactant concentration investigated (0.001–0.5%). All surfactant systems displayed dynamic IFT behavior, in which ultralow transient minima were observed in the range 10⁻⁴–10⁻³ mN m⁻¹, followed by an increase in the IFT to equilibrium values in the range 10⁻³–10⁻¹ mN m⁻¹. The results also showed that with respect to concentration (0.05–0.5%) and temperature (45–80°C), AES-205 and 7–58 surfactants exhibit a wide range of applicability, with the IFT remaining below 10⁻² mN m⁻¹, as required for substantial residual oil recovery. In addition, ultralow IFT were obtained at surfactant concentrations as low as 0.001%, making the use of these surfactants in enhanced oil recovery extremely cost-effective.     

Carotenoids from red palm methyl esters by nanofiltration

Palm oil contains high concentrations of carotenoids and tocopherols that can be recovered by first converting them to methyl esters and then applying membrane technology to separate the carotenoids from the methyl esters. Several solvent-stable nanofiltration membranes were investigated for this application. Flux with a model red palm methyl ester solution ranged from 0.5 to 10 Lm⁻²h⁻¹, and rejection of β-carotene was 60–80% at a transmembrane pressure of 2.76 MPa and 40°C. A multistage membrane process was designed for continuous production of palm carotene concentrate and decolorized methyl esters. With a feed rate of 10 tons per hour of red palm methyl esters containing 0.5 gL⁻¹ β-carotene, the process could produce 3611 L·h⁻¹ of carotene concentrate containing 1.19 gL⁻¹ carotene and 7500 Lh⁻¹ of decolorized methyl esters containing less than 0.1 gL⁻¹ β-carotene. The economics of this process is promising.     

Synthesis of Cleavable Aryl Sulfonate Anionic Surfactants and a Study of their Surface Activity

A series of cleavable aryl sulfonate anionic surfactants were synthesized from cyanuric chloride, aliphatic amine and H-acid mono sodium salt. Their structures were identified by ¹H NMR, Infrared Spectrum (IR) and Elementary Analysis (EA). Their critical micelle concentrations (CMC) in aqueous solutions at 25 °C were determined by a steady-state fluorescence probe method and a surface-tension method. With the increasing length of the carbon chain, the value of their CMCs and surface tensions under CMC (γ _CMC) initially decreased and then reached a minimum (respectively 2.63 × 10⁻⁵ mol L⁻¹ and 28.29 mN m⁻¹) when the carbon number was 10. The CMC and γ _CMC then increased when the carbon number was increased to 12. The results showed that, compared with sodium dodecyl benzene sulfonate (SDBS), such kinds of surfactants have much lower surface adsorption amounts and greater molecular areas on the aqueous surface.

Gas chromatographic separation of cholesteryl esters of fatty acids of different degrees of unsaturation

Cholesteryl esters prepared from the fatty acid methyl esters of linseed oil, pig liver lipids, and Japanese anchovy oil have been separated on the basis of their chain lengths and number of double bonds by gas lipid chromatography on a cyanosiloxane SILAR 10C column. The equivalent chain lengths of cholesteryl esters having acyl groups with 14–22 carbons and 0–6 double bonds are presented. A significant influence of the column temperature on the equivalent chain lengths of the polyenoic fatty acid cholesteryl esters has been found. Separation of the cholestanyl and epicholestanyl esters of linseed oil fatty acids, respectively, under the same conditions is also described.     

Microwave-assisted synthesis of carboxymethylcellulose – based polymeric surfactants

Summary Carboxymethylcellulose (CMC, DS_CM = 1) was partially hydrophobized in order to prepare polymeric surfactants by the transesterification reaction using the methyl ester of the fatty acid complex of rapeseed oil (MERO). The chemical modification was performed in different reaction media (i) DMF/TSA and (ii) H₂O/DMF with and without K₂CO₃ as catalyst, at various reaction conditions and using microwave radiation with controlled power as heating source. The obtained MERO-hydrophobized CMC (MH-CMC) comprising mixed fatty acyl esters were characterized by FT-IR and NMR spectroscopic techniques, which indicated a very low degree of esterification (DS < 0.1). The derivatives showed, in spite of moderate surface tension-lowering effects, excellent emulsifying activity for ‘oil in water’ type emulsions as well as good performance properties including washing power and antiredeposition efficiency. The results suggested that surface-active MH-CMC derivatives can be prepared under microwave heating at reaction times in the range of several minutes, what is a great advantage in comparison to transesterification reactions lasting up to 6 h at conventional heating. The novel CMC esters represent biodegradable polymeric surfactants with potential applications in manufacture of consumer products and in industrial processes.     

Synthesis and properties of N-(α-carboxyalkyl)acrylamide telomer-type surfactants having multihydrocarbon chains

N-(α-Carboxyalkyl)acrylamide telomer-type surfactants (xC _n−1 AmAc where n is alkyl chain length=6, 8, 10, 12; and x is degree of polymerization=3.3–13.1) were synthesized by the telomerization of monomer (C _n−1 AmAc) in the presence of the corresponding alkanethiol as a chain transfer agent and then investigated for their surface-active properties. xC _n−1 AmAc telomers lowered the surface tension of aqueous solutions that were at pH 9–10. The critical micelle concentrations (CMC) of the telomers were lower than those of the monomers with the same alkyl chain length, and the CMC values shifted to lower concentrations with both increasing alkyl chain length and polymerization degree. xC₉AmAc with x=3.3–6.3 gave the highest efficiencies in lowering the surface tension. The cross-sectional molecular areas per molecule of xC _n−1 AmAc telomers were smaller than the values estimated on the assumption that they are assemblies of C _n−1 AmAc monomer units. The foaming abilities and the foam stabilities were both in the orders of xC₇AmAc>xC₉AmAc>xC₅AmAc>xC₁₁AmAc. Mixtures of aqueous solutions of xC _n−1 AmAc telomers and toluene formed oil-in-water emulsions. The emulsion-stabilizing abilities were in the orders of xC₇AmAc>xC₅AmAc>xC₉AmAc=xC₁₁AmAc. The addition of Ca²⁺ to the mixed solutions of telomers and toluene resulted in formation of water-in-oil type emulsions. Thus, the surface-active properties of the telomers were influenced significantly by the alkyl chain length and the polymerization degree of the telomers. In addition, these properties could be correlated with the hydrophilic-lipophilic balance (HLB); the highest surface activities were observed by using xC _n−1 AmAc with HLB of 14–18.     

Incorporation and distribution of saturated and unsaturated fatty acids into nuclear lipids of hepatic cells

Liver nuclear incorporation of stearic (18∶0), linoleic (18∶2n−6), and arachidonic (20∶4n−6) acids was studied by incubation in vitro of the [1-¹⁴C] fatty acids with nuclei, with or without the cytosol fraction at different times. The [1-¹⁴C] fatty acids were incorporated into the nuclei as free fatty acids in the following order: 18∶0>20∶4n−6≫18∶2n−6, and esterified into nuclear lipids by an acyl-CoA pathway. All [1-¹⁴C] fatty acids were esterified mainly to phospholipids and triacylglycerols and in a minor proportion to diacylglycerols. Only [1-¹⁴C] 18∶2n−6-CoA was incorporated into cholesterol esters. The incorporation was not modified by cytosol addition. The incorporation of 20∶4n−6 into nuclear phosphatidylcholine (PC) pools was also studied by incubation of liver nuclei in vitro with [1-¹⁴C]20∶4n−6-CoA, and nuclear labeled PC molecular species were determined. From the 15 PC nuclear molecular species determined, five were labeled with [1-¹⁴C]20∶4n−6-CoA: 18∶0–20∶4, 16∶0–20∶4, 18∶1–20∶4, 18∶2–20∶4, and 20∶4–20∶4. The highest specific radioactivity was found in 20∶4–20∶4 PC, which is a minor species. In conclusion, liver cell nuclei possess the necessary enzymes to incorporate exogenous saturated and unsaturated fatty acids into lipids by an acyl-CoA pathway, showing specificity for each fatty acid. Liver cell nuclei also utilize exogenous 20∶4n−6-CoA to synthesize the major molecular species of PC with 20∶4n−6 at the sn-2 position. However, the most actively synthesized is 20∶4–20∶4 PC, which is a quantitatively minor component. The labeling pattern of 20∶4–20∶4 PC would indicate that this molecular species is synthesized mainly by the de novo pathway.     

Effect of aromatic ring in the alkyl chain on surface properties of arylalkyl surfactant solutions

Surface properties of two series of anionic arylalkyl surfactants, containing different aromatic rings in the straight aliphatic chain, sodium N-aryloleyl-N-methyl-2-aminoethanesulfonates and sodium N-aryloleyl p-methoxyanili-nesulfonates, were investigated. An increase of the aromatic ring size in the alkyl chain increases the critical micelle concentration (CMC) and surface tension at CMC. However, this also decreases the efficiency and effectiveness in reducing water surface tension. The dominant factor of the decrease of efficiency and effectiveness is attributed to the function of the hydrophilic segment and hydrophobic segment for arylalkyl surfactants, respectively. The same results are found in the standard free energy of adsorption (ΔG ^o _ads) and the standard free energy of micellization (ΔG ^o _mic) values. Moreover, with the increase of the aromatic ring size, the adsorption and micellization of arylalkyl surfactants begin to weaken. The data indicate that some parts of surface properties for arylalkyl surfactants are affected by the bulkiness of the arylalkyl chain. The results provide opportunities for further detailed examination of surface properties of arylalkyl surfactants with other branched alkyl chains.     

Preparation and surface-active properties of telomer-type anionic surfactants from maleic anhydride

Maleic acid alkyl ester and N-alkyl maleamic acid monomers (R_nMa and R_nMaAm; n is alkyl chain length; n=6, 8, 10, 12, 14) were synthesized by the reaction of maleic anhydride with alkyl alcohol or alkylamine. The telomerization of R_nMa or R_nMaAm in the presence of alkanethiol as a chain transfer agent gave telomer-type anionic surfactants (xR_nMa, xR_nMaAm; x is total average number of alkyl chains; x=2.8–3.3) having multialkyl chains and multicarboxylate groups. Their surface-active properties were investigated by several techniques such as surface tension, foaming property, and emulsification power measurements. Critical micelle concentrations (CMC) of xR_nMa were 1/110–1/14 of those of R_nMa with the same alkyl chain length. xR_nMa and xR_nMaAm gave higher efficiencies in lowering the surface tension than R_nMa and R_nMaAm in aqueous solutions. In particular, the surface tension of 3.2R₁₂MaAm was 24.4 mN m⁻¹ at the CMC. Foaming abilities and foam stabilities of xR_nMa and xR_nMaAm were higher than those of R_nMa and R_nMaAm. The addition of 300 ppm of Ca²⁺ to the aqueous solutions rendered the telomers less surface active. Shaking the aqueous solutions of telomers with toluene emulsified them. The highly stable oil-in-water type emulsion was formed by using 3.0R₁₀MaAm and 3.2R₁₂MaAm, and the degree of emulsification was kept at a level of about 80% after 60 min of standing. Thus, telomer-type surfactants showed excellent surface activities that were superior to the corresponding monomers as well as to conventional surfactants. The relationship between alkyl chain length of the telomers and the properties of surface tension, foaming, and emulsification was unclear.     

Pure N-Alkylaminopropionic Acid and N-Alkylaminodipropionic Acid Sodium Salts: Synthesis, Characterization, and Physicochemical Properties

Fourteen pure β-aminopropionic acid amphoteric surfactants were synthesized from methyl acrylate using primary amines. The synthesis was done in two steps. First, Michael addition of a primary amine to methyl acrylate gave two separable addition products. Second, because the resulting esters gave, by the classical saponification procedure, undesired retro-Michael products, they were treated with sodium trimethylsilanolate to give the corresponding pure anhydrous acid salt under mild non-aqueous reaction conditions. Two types of amphoteric surfactants were obtained: the monocarboxylate and the dicarboxylate series. The pure surfactants were characterized by IR, ¹H NMR, and ¹³C NMR spectroscopy. The surfactant critical micelle concentrations were evaluated. From these the Gibbs free energy of micellizations [∆G(–CH₂–)_mic] were calculated. These are related to the methylene units that contribute an average of −1.0 (±0.3) kJ mol⁻¹ for both the monocarboxylate and the dicarboxylate series.

Synthesis and Critical Micelle Concentration of a Series of Gemini Alkylphenol Polyoxyethylene Nonionic Surfactants

A series of gemini n-alkylphenol polyoxyethylene surfactants (GAP) were successfully synthesized and their molecular structure were confirmed by NMR and FTIR spectrum. Using the same synthesis route, a gemini nonylphenol polyoxyethylene surfactant (GNP) was synthesized using an industrial nonylphenol product and paraformaldehyde, and its molecular structure was also characterized by ¹H-NMR and FTIR spectra. The optimal reaction conditions were established. The critical micelle concentration (CMC) values of GAP were determined by means of Wilhelmy plate method and steady-state fluorescence probe method. The experimental results show how the lengths of the hydrophilic polyoxyethylene chain and the hydrophobic tail alter the CMC values. The CMC values of the GAP are found to be much lower than those of corresponding conventional single tail nonionic surfactants of the polyethoxylated alkylphenol type, which indicates that the gemini species exhibit a better surface activity.     

Synthesis and Surface-Active Properties of Uronic Amide Derivatives,Surfactants from Renewable Organic Raw Materials

Short chemical syntheses were developed to produce a new set of surfactants from uronic acids derived from widely available raw materials. Three different strategies were used to synthesize uronic amide derivatives, the structures of which were totally characterized by spectrometric methods (IR, MS, ¹H-RMN and ¹³C-RMN). The best one, using an acid chloride as the synthetic intermediate, furnished the expected amides as a mixture of anomers in 46–58% global yield. Surface-active properties (CMC, γ_cmc, Γ_max, A _min) of homologous series of uronic acid N-alkylamides from C8 to C18 were also assessed. In general, these sugar-based surfactants exhibited good surface-activities, and appeared as valuable nonionic surfactants compared to octylphenol 9–10 ethylene oxide condensate, the most well-known nonionic surfactant. Increasing the alkyl chain length influenced the CMC values for both glucuronic and galacturonic N-alkylamide derivatives. The galacturonic N-alkylamides decreased γ_cmc at slower values than their counterpart’s glucuronic N-alkylamides.     

Biodiesel production by the transesterification of cottonseed oil by solid acid catalysts

Methyl esters (biodiesel) were produced by the transesterification of cottonseed oil with methanol in the presence of solid acids as heterogeneous catalysts. The solid acids were prepared by mounting H₂SO₄ on TiO₂ · nH₂O and Zr(OH)₄, respectively, followed by calcining at 823K. TiO₂-SO₄ ²⁻ and ZrO₂-SO₄ ²⁻ showed high activity for the transesterification. The yield of methyl esters was over 90% under the conditions of 230°C, methanol/oil mole ratio of 12:1, reaction time 8 h and catalyst amount (catalyst/oil) of 2% (w). The solid acid catalysts showed more better adaptability than solid base catalysts when the oil has high acidity. IR spectral analysis of absorbed pyridine on the samples showed that there were Lewis and Br?nsted acid sites on the catalysts. Translated from The Chinese Journal of Process Engineering, 2006, 6(4): 571–575 [译自: 过程工程学报]     

Surfactant property of linear alkanes with two pyrrolidone moieties in both termini

Linear alkanes with two pyrrolidone groups in both termini [abbreviation: 1,n-dipyrrolidonyl alkane (1,n-DPA) (n=3, 5, 9, and 12)] were synthesized. Their surface activities were evaluated in terms of surface tension, and compared with those of a few kinds of surfactants. Among 1,n-DPAs, 1,3-, 1,5-, and 1,9-DPAs were fully soluble in water and surface-active: especially 1,9-DPA showed a surface tension value of γW/A 32.8 mN/m at 5.9×10⁻² mol/L or 1.7 wt% and was suggested as a nonionic surfactant with simple structure and moderate activity. Critical miceller concentration (CMC) of 1,9-DPA was 1.45×10⁻² mol/L. Surface tension values of 1,5- and 1,9-DPAs were lower than those of the corresponding monofunctional pyrrolidones, N-propyl and N-pentylpyrrolidones. Minimum area per surfactant molecule (A_min) decreased with increase of methylene chain length in the series of 1,n-DPAs. The results suggested that 1,n-DPA favorably chooses a loop structure at air/water interface.     

Sugar fatty acid ester surfactants: Structure and ultimate aerobic biodegradability

Ultimate aerobic biodegradabilities of an array of sugar ester surfactants were determined by International Standards Organisation method 7827, “Water Quality—Evaluation in an Aqueous Medium of the Aerobic Biodegradability of Organic Compounds, Method by Dissolved Organic Carbon” (1984). The surfactants were nonionic sugar esters with different-sized sugar head groups (formed from glucose, sucrose, or raffinose) and different lengths and numbers of alkyl chains [formed from lauric (C₁₂) or palmitic (C₁₆) acid]. Analogous anionic sugar ester surfactants, formed by attaching an α-sulfonyl group adjacent to the ester bond, and sugar esters with α-alkyl substituents were also studied. It was found that variations in sugar head group size or in alkyl chain length and number do not significantly affect biodegradability. In contrast, the biodegradation rate of sugar esters with α-sulfonyl or α-alkyl groups, although sufficient for them to be classified as readily biodegradable, was dramatically reduced compared to that of the unsubstituted sugar esters. An understanding of the relationship between structure and biodegradability provided by the results of this study will aid the targeted design of readily biodegradable sugar ester surfactants for use in consumer products.     

The energetics of surfactant adsorption at the air-water interface

The standard free energy, enthalpy, and entropy changes (ΔG, ΔH, and ΔS, respectively) for the adsorption at the air-water interface of a commercial ethylene oxide (EO) adduct of straight chain nonylphenol from monomer solution at the critical micelle concentration (CMC) have been calculated from surface tension-concentration data at 21C–45C using the Gibbs equation, the standard free energy change equation ΔG=−RT (In interfacial monomer concentration/CMC), and the Gibbs-Helmholtz equation which gave ΔH directly from the slope of the (ΔG/T) vs (1/T) function. The CMC and surface tension at the CMC (γCMC) decreased, and −ΔG and molecular area increased slightly, with increasing temperature. The ΔH and ΔS values were positive, and appear explainable by the postulations applied to micellization. At ambient temperature (28C) an increase in the (EO) mol ratio of straight chain nonylphenol and C₁₃ secondary alcohol ethoxylates resulted in increases of CMC, γCMC, and molecular area, and slight decreases in −ΔG. A comparison of the 9 (EO) mol ratio adducts of C₁₃ straight chain primary and secondary alcohols showed that the CMC and molecular area of the secondary alcohol ethoxylate were larger, and the γCMC and −ΔG smaller, than the corresponding values of the primary alcohol ethoxylate.