Study of the competition between homogeneous and interfacial reactions during the synthesis of surfactant sucrose hydroxyalkyl ethers in water (original) (raw)
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Journal of Molecular Catalysis A: Chemical, 2002
The addition of sucrose on two fatty epoxides, 1,2-epoxydodecane and 1,2-epoxydodecan-3-ol, has been studied in DMSO and water. The study of the kinetics of the reaction showed that the 1,2-epoxydodecan-3-ol is more reactive for both interfacial and electronic reasons. In water, the induction time normally necessary is dramatically reduced with an immediate emulsification of the mixture which is beneficial to the interfacial formation of sucrose ethers. The comparison of the reaction in DMSO allowed to estimate the assistance of the ␣-hydroxyl group through intramolecular hydrogen bonding in 1,2-epoxydodecan-3-ol, revealing that both aspects are involved in the catalysis of the reaction in aqueous medium.
Synthesis in water of amphiphilic sucrose hydroxyalkyl ethers
Tetrahedron Letters, 1999
We describe the preparation of amphiphilic hydroxyalkylsucrese ethers from unprotected sucrose in water and we show that among the monosubstituted products, the 2-and 1'-regioisomers account for 60% of the mixture. The high reactivity of these positions is thus confL, med in water as it is in dipolar aprotic solvents. A careful analysis also show evidence of the formation of oligomerisation products as by-products.
Enzyme Catalyzed Regioselective Synthesis of Sucrose Fatty Acid Ester Surfactants
Journal of Carbohydrate Chemistry, 1997
In this review, a comprehensive and illustrative survey is made of the regioselective synthesis of esters of sugars and related compounds using lipases. The main emphasis has been given to the screening and use of commercially available lipases for the enzymatic esterification of neutral monosaccharides, disaccharides, sugar alcohols and their selected ether and ester derivatives. The effect of solvents and solubilizing agents in improving the yields of the resultant sugar fatty acid esters has been incorporated. Further, solvent-free esterification with molten fatty acids, use of ionic liquids and microwave radiations for improvement in the methodology have also been discussed.
Production of sucroesters using solvent-free reactive systems containing emulsifiers
The transesterification reaction of sucrose and fatty acid methyl esters to produce sucroesters was experimentally evaluated using commercial emulsifiers as compatibility agents. Reactions were carried out at temperatures between 100 and 140°C, using emulsifier concentrations in the range of 5 to 15 %wt, and potassium carbonate as catalyst. Fatty acid methyl esters consumption and sucroesters production was monitored by HPLC analysis of samples. Methyl esters conversions around 40 % were obtained with 68 %wt monoester content in sucroesters mixture. Despite the reaction times were reduced by operating at high temperatures and high emulsifier's concentration, multiple substitution and color degradation were observed. Higher productivities of sucroester and higher selectivity to monoesters were obtained when potassium palmitate was used as contacting agent. The lower monoester content in the final product was obtained when using a commercial sucroester emulsifier. Results of this study can be used for preliminary process design in a solvent-free production of biobased sucroesters.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2002
The behaviour of various sucrose fatty acid esters blends in pseudoternary mixtures {water/methyl stearate/sucrose ester+propanol or ethanol} was explored. The qualitative and quantitative analysis of the phases gave information on the distribution of the surfactant and the oil in the polyphasic systems. It was seen that the transitions between Winsor systems of type I-III can be obtained by using propanol as cosurfactant. Transition from a Winsor I behaviour to a Winsor II behaviour was observed, depending on the substitution degree of the sucrose ester. Marked differences can also be seen by this method between sucrose esters blends containing same contents of monoesters, but differing by the content of minor products, especially soaps. The Winsor behaviour can thus be used as a 'fingerprint' to distinguish different sucrose ester batches.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2022
Three new amphiphilic molecules were synthetized on a basis of a common monomer, octadecyl succinic anhydride (OSA), on which were grafted different PEGylated hydrophilic polar head. The objective of this study is to investigate a potential relationship between the chemical structure of the surfactant, and the efficiency to generate nano-emulsions through the spontaneous nano-emulsification method. Beyond the innovative synthesis and comparison of these amphiphiles, a comprehensive comparison is suggested, comparing size distribution and polydispersity for the different composition parameters, as well making a bridge with critical micelle concentration and hydrophile lipophile balance (HLB). Using OSA monomeric entity as common hydrophobic moiety, the variations in the surfactant molecules were done on the hydrophilic moiety, through the addition of one or two Jeffamine chains in different configurations, so-called C 18 ⊖-PEG, C 18-PEG and C 18-PEG 2. The results disclosed that C 18 ⊖-PEG allows producing smallest size distribution and lowest PDI values. Moreover, C 18 ⊖-PEG presents the highest critical micellar concentration, linked to a higher hydrophilicity of the molecule. This impacts the balance between surfactant affinity for oil and aqueous phases, a point probably related to the spontaneous emulsification efficiency. A last part of the study regarded the optimization of the emulsification efficiency, through a systematic study in ternary composition map, to disclosed that the best conditions are included in the lower surfactant concentrations, for water and oil contents higher and lower than 50%, respectively. The main idea behind this study was to bring further insights into the unclear relationship between the chemical structure of nonionic surfactants, and the efficiency of the emulsification by spontaneous low-energy method.
Journal of Dispersion Science and Technology, 1997
Neutral polymeric surfactants were synthesized by covalent attachment of hydrophobic groups (aromatic rings) onto a polysaccharide backbone (dextran). By changing the conditions of the modification reaction, the number of grafted hydrophobic groups per 100 glucopyranose units (substitution ratio) was varied between 7 and 22. In aqueous solution, these polymers behaved like classical associative polymers as demonstrated by viscometric measurements. The associative behavior was more pronounced when the substitution ratio increased. The surface-active properties of the modified dextrans were evidenced by surface tension (air/water) and interfacial tension (dodecane/water) measurements. In each case the surface or interfacial tension leveled down above a critical polymer concentration, which was attributed to the formation of a dense polymer layer at the liquid-air or liquid-liquid interface. Dodecane-in-water emulsions were prepared using the polymeric surfactants as stabilizers, with oil volume fractions ranging between 5 and 20%. The oil droplet size (measured by dynamic light scattering) was correlated to the amount of polymer in the aqueous phase and to the volume of emulsified oil. The thickness of the adsorbed polymer layer was estimated thanks to zeta potential measurements coupled with size measurements. This thickness increased with the amount of polymer available for adsorption at the interface. The dextran-based surfactants were also applied to emulsion polymerization of styrene and stable polystyrene particles were obtained with a permanent adsorbed dextran layer at their surface. The comparison with the use of an unmodified dextran indicated that the polymeric surfactants were densely packed at the surface of the particles. The colloidal stability of the suspensions of polystyrene particles as well as their protection against protein adsorption (bovine serum albumin, BSA, used as a test protein) were also examined.
Self-Aggregation and Emulsifying Properties of Methyl Ester Sulfonate Surfactants
Journal of Surfactants and Detergents, 2017
Methyl ester sulfonate (MES) anionic surfactants made from natural resources are of particular interest as sustainable surfactants. They offer good physicochemical properties for applications as detergents and emulsifiers. The liquid crystal structures of MES surfactants synthesized in a previous work were determined by polarizing optical microscopy (POM) and small-angle X-ray scattering (SAXS). The emulsifying activity for each surfactant was also measured, and the stability of emulsions was estimated and compared to that induced by sodium dodecyl sulfate (SDS). The POM micrographs showed the presence of birefringent textures. Several factors, including temperature and hydration, influenced the stability of the phases and their structure. SAXS confirmed the structure of the phases formed by dry and hydrated a-MES surfactants at 25°C, giving the position of peaks corresponding to the ratio 1:2:3 and revealing the phase transitions of lamellar to double lamellar or the reverse. Also, the Bragg distance (d) decreased with an increase in chain length from 13 to 17 carbon atoms and an increase in the area per molecule of surfactant. The geometric packing parameters were also determined, and suggest that surfactants are tilted. The stability of surfactant emulsions is around 60%, which is comparable to that of SDS. The micrographs show that the emulsions formed are O/W, and an increase in chain length gives rise to a decrease in the size of the emulsion droplets. These results are confirmed by the values of hydrophilic-lipophilic balance (HLB) which reveals the hydrophilic nature of these surfactants.
Process Biochemistry, 2022
The enzymatic synthesis of sugar-based surfactants is often performed in non-conventional media that do not meet longer satisfy the current environmental acceptability, especially biodegradability and cytotoxicity. In this work, we propose an innovative sustainable route by replacing the current reference organic solvent, 2-methyl-2-butanol (2M2B), by 2methyltetrahydrofuran (MeTHF), an agrosolvent and 2-methyltetrahydrofuran-3-one (MeTHF-3-one), a food-grade ingredient used as solvent. These two neoteric solvents were thus evaluated as reaction media via lipase-catalyzed esterification of glucose by lauric acid and revealed a novel matter of interest. The regioselectivity of the reaction was mainly directed toward the primary alcohol of glucose maintaining the end-product obtained in 2M2B: D-glucose-6-O-laurate. The PLS-Surface Response Design evidenced enzymatic performances in ester production of 48% in MeTHF and 79% in MeTHF-3-one. The latter solvent resulted not only in better yields compared to 2M2B, but also in an increased enzymatic stability allowing better reuse of the catalyst. Demonstrated to be readily biodegradable according to OECD standards for the first time, MeTHF-3-one was substantiated as a green medium for efficient, selective and sustainable enzymatic synthesis of sugar esters.