| 1. |
- Holmberg, K, et al.
(författare)
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Microemulsions as reaction medium for a substitution reaction
- 1996
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Ingår i: Progress in Colloid and Polymer Science. - 0340-255X .- 1437-8027. ; 100, s. 281-285
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Tidskriftsartikel (refereegranskat)abstract
- Synthesis of sodium decyl sulfonate from 1-bromodecane and sodium sulfite was performed in microemulsions based on nonionic surfactant, in liquid crystals and in 2-phase systems with or without a phase transfer agent added. The reactions were fast in both bicontinuous and W/O microemulsion, slower in liquid crystal and very sluggish in 2-phase systems also in the presence of a Q salt or a crown ether. Addition of a small amount of anionic surfactant to the microemulsion systems decreased reaction rate. Addition of cationic surfactant either increased or decreased the reaction rate depending on the choice of counterion.
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| 2. |
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| 3. |
- Oh, S-G, et al.
(författare)
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Effect of hydrocarbon chain length on yield of lipase catalyzed triglyceride synthesis in microemulsion
- 1996
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Ingår i: Journal of Colloid and Interface Science. - 0021-9797 .- 1095-7103. ; 181, s. 341-343
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Tidskriftsartikel (refereegranskat)abstract
- Previous work on lipase catalyzed esterification of glycerol with fatty acids in w/o microemulsions gave monoglyceride as the main reaction product. Only traces of triglyceride were obtained. We show here that the reason triglycerides are not formed in these systems is that the diglyceride formed in the oil-water interfacial zone partitions into the continuous hydrocarbon domain. It is then inaccessible to the enzyme. The yield of triglyceride is increased by using longer hydrocarbons as the oil component. These have poorer solvency for mono- and diglycerides. When the hydrocarbon chain length exceeds that of the glyceride acyl groups, triglyceride is the main reaction product.
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| 4. |
- Oh, S-G, et al.
(författare)
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Microemulsions as reaction media for synthesis of sodium decyl sulfonate II: Role of ionic surfactants
- 1995
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Ingår i: Colloids and Surfaces A. - 0927-7757 .- 1873-4359. ; 104, s. 217-222
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Tidskriftsartikel (refereegranskat)abstract
- Synthesis of sodium decyl sulfonate in various types of microemulsions based on nonionic surfactants have been reported in our previous paper. As a continuation of this study the effect of ionic surfactants with different counterions on the reaction profile was investigated. As expected, the electrical potential of microemulsion droplets significantly influenced the degree of conversion probably by affecting the diffusion of ionic species into the interfacial region where the reaction occurs. The reaction yield was also highly dependent on the type of counterions. Tetradecyl trimethyl ammonium acetate increased the yield, but sodium dodecyl sulfate and tetradecyl trimethyl ammonium bromide gave decreased conversion. The counterion effect was explained by the competitive association of ions with the surfactant monolayer at the oil/water interface.
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| 5. |
- Oh, S-G, et al.
(författare)
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Microemulsions as reaction medium for synthesis of sodium decyl sulfonate I: Role of microemulsion composition
- 1995
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Ingår i: Colloids and Surfaces A. - 0927-7757 .- 1873-4359. ; 97, s. 169-179
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Tidskriftsartikel (refereegranskat)abstract
- Reaction kinetics for the formation of sodium decyl sulfonate from alkyl halide and sodium sulfite in microemulsions based on nonionic surfactant were investigated and compared with those in oil-water two-phase systems. Reactions were run at room temperature at various oil-water ratios. Whereas at room temperature almost no reaction occurred in the two-phase systems. all microemulsion-based reactions proceeded at a fair rate. No clear relationship between microemulsion structure and reaction rate could be seen. An equation describing reaction kinetics in the microemulsion system has been derived based on the pseudophase model.
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