Enhanced activity of polymer-supported phase transfer catalysts

Desikan, Sridhar; Doraiswamy, L. K.

doi:10.1016/s0009-2509(00)00221-9

Cited by 34 publications

(29 citation statements)

References 8 publications

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“…We can observe the maximum in concentration at all radial positions. This behavior is similar to that observed in our previous model for isothermal reaction (Desikan and Doraiswamy, 1995). The maximum in reactant concentration is observed only for the organic reactant.…”

Section: Resultssupporting

confidence: 91%

“…In our previous paper (Desikan and Doraiswamy, 1995), we developed a dynamic model for tri phase catalyzed reaction which takes into account the reversible ion exchange reaction. In all the modeling work carried out so far, the reaction was considered to be isothermal.…”

Section: Discussionmentioning

confidence: 99%

“…The assumptions made in deriving the mass balance expressions and their validity have been presented in our previous paper on isothermal model (Desikan and Doraiswamy, 1995).…”

Section: Bim = F^rx^/^rxmentioning

confidence: 99%

“…Only a few papers have been published to address the complex problem of diffusion-reaction in tri phase catalysis Yang, 1991,1992;Desikan and Doraiswamy, 1995). In our previous paper in this area, we presented a dynamic model of triphase catalysis that takes into account the reversibility of the aqueous phase ion exchange reaction.…”

Section: Introductionmentioning

confidence: 99%

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Studies in immobilized phase transfer catalysis

Desikan

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This manuscript has been reproduced from the microfilm master. UMI films the text directly fi-om the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter &ce, vMe others may be fi'om ai^ type of computer printer.The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleedthrough, substandard margins, and improper alignment can adversely affect reproduction.In the unlikely event that the author did not send UMI a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion.Oversize materials (e.g., maps, drawings, charts) are reproduced by sectioning the original, beginning at the upper left-hand comer and continuing fi'om left to right in equal sections with small overlaps. Each original is also photographed in one exposiu-e and is included in reduced form at the back of the book.Photographs included in the original manuscript have been reproduced xerographically in this copy. Higher quality 6" x 9" black and white photographic prints are available for any photographs or illustrations appearing in this copy for an additional charge. Contact UMI directly to order. The main reason for the lack of industrial in triphase catalysts is their reduced activity due to diffusional limitations. Another reason is the lack of understanding of the complex diffusionreaction problem associated with triphase catalysis. UMIThe objective of this work is to understand the principles behind triphase catalysis to make it industrially attractive. A detailed mathematical model has thus been developed to study the diffusion-reaction problem in triphase catalysis. Also, experimental work in developing an optimal support for phase transfer catalyst has been carried out A review of the field is given followed by the development of a mathematical model for liquid-liquid-solid triphase catalysis.Simulation studies show that the reversibility of the ion exchange reaction in the aqueous phase plays a significant role in the overall conversion.In order to understand the effect of nonisothermality of the reaction, a dynamic model for triphase catalysis system which includes intraparticle heat transfer effects was developed.It was found that for highly exothermic reactions, catalyst effectiveness greater than unity could be obtained. Another significant observation is that in an unsteady state reactor, like the slurry reactor used in the present work, there is an optimum with respect to the reaction time.To address the issue of reduced activity of triphase catalysts in comparison to their solu ble analogs, experimental work was carried out on esterification of benzyl chloride with aqueous vi sodium acetate using solid supported phase transfer catalyst. Reactivities of the triphase cata lysts were compared with those of comparable soluble phase transfer catalysts. The polymer bound tributylmeth...

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Section: Resultssupporting

confidence: 91%

Section: Discussionmentioning

confidence: 99%

“…The assumptions made in deriving the mass balance expressions and their validity have been presented in our previous paper on isothermal model (Desikan and Doraiswamy, 1995).…”

Section: Bim = F^rx^/^rxmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Studies in immobilized phase transfer catalysis

Desikan

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“…Wang and Yang [7] developed a mathematical model of pseudo-steady-state approach including the considerations of mass transfer of reactants in the bulk phases, the diffusion of reactants within the catalyst pores, and the intrinsic reactions of the reactants for an etherification conducted in a solid-liquidliquid system. Desikan and Doraiswamy [8] explored the activity of triphase catalysts for the esterification of benzyl chloride with aqueous sodium acetate, and found that the triphase catalyst has a higher reactivity than its soluble analogs. A kinetic model based on the Langmuir-Hinshelwood and Eley-Rideal types was developed for nucleophilic substitution by considering the reaction rate occurred in the active site of a triphase catalyst to be the rate-limiting step [9].…”

Section: Introductionmentioning

confidence: 99%

Green Conversion of Phenolic Compound to Benzoate Over Polymer-Supported Phase-Transfer Catalysts

Yang

Huang

2008

Catal Lett

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The conversion of sodium phenoxide into benzoates over polymer-supported phase-transfer catalysts with trialkylamines as the functional groups (triphase catalysis) was investigated. The yield of product phenyl benzoate was 100% in 1 h of reaction using a small amount of tributylamine catalyst supported on 1.38% divinylbenzene (DVB) cross-linked copolymer (40-80 mesh) of styrene and chloromethylstyrene. During the reaction, the catalyst stays between the aqueous and organic phases. The overall reaction rate was strongly dependent on the stirring speed and the ionic exchange of Cl(-) of the catalyst with PhO(-) in the interfacial region. The reaction rate decreased with increasing the mean particle sizes for 1.38% DVB catalyst. The variation of the catalytic intermediate within the catalyst was determined to verify the reaction mechanism. A kinetic model was also proposed to correlate the reaction rate constants. The efficient conversion of phenolic compounds over polymer-supported catalysts shows that triphase catalysis is an efficient green technology in chemical synthesis

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Preparation of polymer‐supported polyethylene glycol and phase‐transfer catalytic activity in benzoate synthesis

2009

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The crosslinked polymeric microspheres (GMA/MMA) of glycyl methacrylate (GMA) and methyl methacrylate (MMA) were prepared by suspension polymerization. Polyethylene glycol (PEG) was grafted on GMA/MMA microsphers via the ring‐opening reaction of the epoxy groups on the surfaces of GMA/MMA microspheres, forming a polymer‐supported triphase catalyst, PEG‐GMA/MMA. The Phase‐transfer catalytic activity of PEG‐GMA/MMA microspheres was evaluated using the esterification reaction of n‐chlorobutane in organic phase and benzoic acid in water phase as a model system. The effects of various factors on the phase transfer catalysis reaction of liquid–solid–liquid were investigated. The experimental results show that the PEG‐GMA/MMA microspheres are an effective and stable triphase catalyst for the esterification reaction carried out between oil phase and water phase. The polarity of the organic solvent, the ratio of oil phase volume to water phase volume and the density of the grafted PEG on PEG‐GMA/MMA microspheres affect the reaction rate greatly. For this investigated system, the solvent with high polarity is appropriate, an adequate volume ratio of oil phase to water phase is 2:1, and the optimal PEG density on the polymeric microspheres is 15 g/100 g. Triphase catalysts offer many advantages associated with heterogeneous catalysts such as easy separation from the reaction mixture and reusability. The activity of PEG‐GMA/MMA microspheres is not nearly decreased after reusing of 10 recycles. © 2009 American Institute of Chemical Engineers AIChE J, 2010

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Enhanced activity of polymer-supported phase transfer catalysts

Cited by 34 publications

References 8 publications

Studies in immobilized phase transfer catalysis

Studies in immobilized phase transfer catalysis

Green Conversion of Phenolic Compound to Benzoate Over Polymer-Supported Phase-Transfer Catalysts

Preparation of polymer‐supported polyethylene glycol and phase‐transfer catalytic activity in benzoate synthesis

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