The Kinetics of an Interfacial Reaction in a Microemulsion

Tjandra, Djanarko; Lade, Markus; Wagner, Ortwin; Schomäcker, Reinhard

doi:10.1002/(sici)1521-4125(199808)21:8<666::aid-ceat666>3.3.co;2-d

Cited by 4 publications

(7 citation statements)

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“…As expected, the rate constant increases with increasing volume fraction of surfactant. These results are in agreement with an observation made for a similar interfacial reaction model where the total interfacial area was calculated from known values of the headgroup area of the nonionic surfactant . The assumption that there is only a small concentration difference for KI between bulk water and interface is supported by recent studies of iodide binding to the interface.…”

Section: Discussionsupporting

confidence: 90%

A Nucleophilic Substitution Reaction Performed in Different Types of Self-Assembly Structures

2004

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A nucleophilic substitution reaction between 4-tert-butylbenzyl bromide and potassium iodide has been performed in oil-in-water microemulsions based on various C12Em surfactants, i.e., dodecyl ethoxylate with m number of oxyethylene units. The reaction kinetics was compared with the kinetics of reactions performed in other self-assembly structures based on very similar surfactants and in homogeneous liquids. The reaction was fastest in the micellar system, intermediate in rate in the microemulsions, and most sluggish in the liquid crystalline phase. Reaction in a Winsor I system, i.e., a two-phase system comprising an oil-in-water microemulsion in equilibrium with excess oil, was equally fast as reaction in a one-phase microemulsion. The reactions in microemulsion were surprisingly fast compared to reaction in homogeneous, protic liquids such as methanol and ethanol. The rate was independent of the microstructure of the microemulsion; however, the rate was very dependent on the type of surfactant used. When the C12Em surfactant was replaced by a sugar-based surfactant, octyl glucoside, the reaction was much more sluggish. The high reactivity in microemulsions based on C12Em surfactants is belived to be due to a favorable microenvironment in the reaction zone. The reaction is likely to occur within the surfactant palisade layer, where the water activity is relatively low and where the attacking species, the iodide ion, is poorly hydrated and, hence, more nucleophlic than in a protic solvent such as water or methanol. Sugar surfactants become more hydrated than alcohol ethoxylates and the lower reactivity in the microemulsion based on the sugar surfactant is probably due to a higher water activity in the reaction zone.

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Section: Discussionsupporting

confidence: 90%

A Nucleophilic Substitution Reaction Performed in Different Types of Self-Assembly Structures

2004

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“…The intercepts of the plots using i-octane and n-hexadecane at the origin of the coordinate system show that the reaction occurs only at the interface and not in the bulk phase, as it was shown for the single-phase toluene microemulsion in ref. [5]. The intercept derived from the experiments using chlorobenzene shows that in this case the reaction occurs partly in the bulk phase.…”

Section: Kineticsmentioning

confidence: 99%

“…A recent analysis [5] showed that the synthesis of 1-phenoxyoctane from 1-bromooctane and sodium phenoxide takes place only at the interface of the microemulsion, and that there is no concentration gradient between the core of the droplets and the internal interface. This result was deduced from a systematic variation of a and g.…”

Section: Introductionmentioning

confidence: 99%

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The Kinetics of an Interfacial Reaction in Microemulsions with Excess Phases

Bode¹,

Lade²,

Schomäcker³

2000

Chem. Eng. Technol.

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This work examines the reaction kinetics of the syntheses of 1-phenoxyoctane from 1-bromooctane and sodium phenoxide in microemulsions with excess phases. It can be shown that an interfacial reaction model proposed in a previous paper [5] which describes the kinetics of the same reaction in a singlephased microemulsion can also be applied to two-phase systems. In this model the microemulsion is divided into an aqueous and an organic subvolume. The reaction takes place only at the interface between these subvolumes which is covered by a monolayer of surfactant molecules. This study shows that at constant temperatures the reaction rate is proportional to the fraction of surfactant in the microemulsion and therefore to size of the interfacial area. It does not depend on the presence and the size of excess phases.

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“…1 This characteristic combined with their large liquid-liquid interfacial area allows for a fast diffusion between phases. 2 Recently, the application of micellar systems and microemulsions as thermodynamically stable biphasic systems has been demonstrated in the synthesis of a variety of fine chemicals by catalytic reactions. 3 The green chemistry aspect of using water, an environmentally and user-friendly solvent for chemical reactions, has sparked much interest with an impressive number of contributions.…”

Section: Introductionmentioning

confidence: 99%

Catalytic Reactions in Surfactant Systems:Product Isolation and Catalyst Recycling

Milano-Brusco¹,

Nowothnick²,

Schwarze³

et al. 2010

Ind. Eng. Chem. Res.

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The potential of surfactant based reaction media was studied with different homogeneous catalytic reactions. Micellar systems with the surfactants (p-tert-octylphenoxy) polyethoxyethanol (Triton X-100) and dodecyl sulfate sodium salt were used as reaction media for the enantioselective catalytic hydrogenation of dimethyl itaconate (DMI) with the Rh catalyst complexed with the chiral ligand (2S,4S)-1-tert-butoxycarbonyl-4diphenylphosphino-2-(diphenylphosphinometyl)-pyrrolidine (BPPM) at 30 °C and 1.1 bar, obtaining an enantiomeric excess (ee) of up to 69%. After complete hydrogenation was achieved, micellar enhanced ultrafiltration (MEUF) was used to recycle the catalyst achieving up to 95% retention. A microemulsion system stabilized with the surfactant Triton X-100 was used as alternative reaction media for the hydrogenation of DMI with a Rh catalyst complexed with the water-soluble tris(3-sulfophenyl)phosphine trisodium salt (TPPTS) at 50 °C and 1.1 bar. With the Triton X-100 system, phase separation by temperature induced separation allowed for up to four repetitive batches of DMI hydrogenations, resulting in a TON of 1530. Suzuki coupling for the synthesis of 4′-methyl-2-biphenylcarbonitrile proceeded faster in a narrow range alkylpolyglycol ether (Novel 8 ) Novel 1216CO-8 Ethoxylate) three-phase system than in an dioctyl sulfosuccinate sodium salt (AOT) two-phase system, demonstrating the retarding effect of the salinization on the reaction rate.

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The Kinetics of an Interfacial Reaction in a Microemulsion

Cited by 4 publications

References 0 publications

A Nucleophilic Substitution Reaction Performed in Different Types of Self-Assembly Structures

A Nucleophilic Substitution Reaction Performed in Different Types of Self-Assembly Structures

The Kinetics of an Interfacial Reaction in Microemulsions with Excess Phases

Catalytic Reactions in Surfactant Systems:Product Isolation and Catalyst Recycling

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