Polydimethylsiloxane membrane

Agantonovic-Kastrin S, Beresford R, Yusof AP (2001) ANN modeling of the penetration across a polydimethylsiloxane membrane from theoretically derived molecular descriptors. J Pharm Biomed Anal 26 241-254. 

Chen Y, Vayuhauwan P, Matheson LE (1996) Prediction of flux through polydimethylsiloxane membranes using atomic charge calculations application to an extended data set. Int J Pharm 137 149-158. 

Cronin MTD, Dearden JC, Gupta R, Moss GP (1998) An investigation of flux across polydimethylsiloxane membranes by use of quantitative structure-permeability relationship. J Pharm Pharmacol 50 143-152. 

Chen, Y., P. Vayumhasuwan, and L. E. Matheson. 1996. Prediction of ux through polydimethylsiloxane membranes using atomic charge calculations Application to an extended datatsdt. Pharm. 

Liu, R. and L. E. Matheson. 1994. Comparative molecular eld analysis combined with physicochemical parameters for the prediction of polydimethylsiloxane membrane ux in isopro[58iHjlm. Res. 11 257-266. 

S.Y. Lu, C.P. Chiu, FLY. Fluang, Pervaporation of acetic acid/water mixtures through silicate filled polydimethylsiloxane membranes, J. Membr. Sci. 176 (2002) 159-167. 

A FePc complex encaged in the zeolite Y supercages, in its turn, can be wrapped in a polydimethylsiloxane membrane, thus acting not only as a mechanistic but also as a formal mimic of Cytochrome P450 often found in cell membranes.[57] Such membranes, contacted on one side with substrate and on the other side with oxidant, catalyse oxygenation reactions in a membrane reactor in the absence of any solvent, the majority of the product amount being recovered from the more polar phase. 

Agatonovich-Kustrin S, Beresford R, Yusof APM (2001) ANN modeling of the penetration across a polydimethylsiloxane membrane from theoretically derived molecular descriptors. J Pharm Biomed Anal 25 227-237 Baroni M, Costantino G, Cruciani G et aL (1993) Generating optimal linear PLS estimations (GOLPE) An advanced chemometric tool for handling 3D-QS AR problems. Quant Struct-Act Relat 12 9-20... 

Scheme 6 Jacobsen s complex entrapment into a) zeolite b) polydimethylsiloxane membrane c) MCM-41.

One of the most smdied examples is the mimic of the enzyme cytochrome P-450 in the pores of a faujasite zeolite [196,204,225], The iron-phthalocyanine complex was encapsulated in the FAU supercage and is used as oxidation catalyst for the conversion of cyclohexane and cyclohexanone to adipic acid, an important intermediate in the nylon production. In this case the two step process using homogeneous catalysts could be replaced by a one step process using a heterogeneous catalyst [196]. This allowed better control of the selectivity and inhibited the auto oxidation of the active compound. In order to simulate a catalyst and the reaction conditions which are close to the enzymatic process, the so obtained catalyst was embedded in a polydimethylsiloxane membrane (mimics the phospholipid membrane in the living body) and the membrane was used to limit oxygen availability. With this catalyst alkanes were oxidized at room temperature with rates comparable to those of the enzyme [205]. 

More recently, these systems have been elevated to a new level of biomimetic sophistication, namely by embedding the zeolite-encapsulated complex in a polydimethylsiloxane membrane their performance could be improved even further [81]. The hydrophobic membrane mimics the pho holipid membrane in which cytochrome P-450 resides and acts as an interface between two immiscible phases (cyclohexane and aqueous 70%TBHP). 

A Rh complex of JOSIPHOS, a non-C2 chiral diphosphine, is effective for asymmetric hydrogenation of ethyl 3-oxobutanoate [26]. Hydrogenation of methyl 3-oxobutanoate catalyzed by a BINAP-Ru complex and p-toluenesulfonic acid immobilized in a polydimethylsiloxane membrane matrix gives a chiral alcohol in 92% ee [27]. The reaction rate is comparable with that of the homogeneous system. 

Another path of manufacture of practical catalysts is using immobilized chiral metal complexes. Thus, the complex [Rh-BESIAP] was occluded in an elastomeric t5T)e polydimethylsiloxane membrane, which gave a re-generable active membrane-catalyst with the same enantioselectivity as the homogeneous catalyst in the hydrogenation of acetoacetic acid ester into methyl (7 )-(-)-3-hydroxybutyrate, that can be pol5mierized into polyester (Scheme 7.17.). 

The most important class of solid-state enzyme mimics is based on zeolites. Zeolites are solid materials composed of Si04 or AIO4 tetrahedra linked at their corners, affording a three-dimensional network with small pores of molecular dimensions. They possess a unique feature of a strictly uniform pore diameter. In particular, zeolites with encapsulated metal complexes are used as inimics of cytochrome P-450.An efficient enzyme mimic was obtained by encapsulating an iron phthalocyanine complex into crystals of zeolite Y, which were, in turn, embedded into a polydimethylsiloxane membrane acting as a mimic of the phospholipid membrane.With t-butylhydroperoxide as the oxidant, the system hydroxyl-ates alkanes at room temperature with rates comparable to those for the enzyme. It shows similar selectivity (preference oxidation of tertiary C-H bonds) and a large kinetic isotope effect of nine. 

Hydrophobic/hydrophilic membranes for recovery of biofuel and dehydration, respectively Composite polydimethylsiloxane membrane... 

Wu Y, Huang W, Xiao Z, Zhang Y. 2004. Ethanol recovery from fermentation broth by pervaporation using a composite polydimethylsiloxane membrane. Chin. J. Chem. Eng. 12(4) 586-589. 

P. Izak, W. Ruth, Z. Fei et al.. Selective removal of acetone and butan-l-ol from water with supported ionic liquid-polydimethylsiloxane membrane by pervaporation. Chem. Engin. J. 139 (2008) 318-321. 

In the case of gasoline vapor recovery two types of membranes are used the PDMS (polydimethylsiloxane) membrane and the POMS (polyoctylmethylsilox-ane) membrane. 

Miller, A. L., and Bowden, N. B. (2007). Room temperature Ionic liquids new solvents for Schroclds catalyst and removal using polydimethylsiloxane membranes. Chem. Commun., pp. 2051-2053. 

Table m. Average Diffusion Rates of Various Steroids Across Polydimethylsiloxane Membrane ... 

FIGURE 9.10 Effect of feed sulfur content on sulfur enrichment factor for binary n-heptane-sulfur mixtures. (Reprinted from Separation and Purification Technology, 63, Zhao, C., Li. J., Qi, R., Chen, J., and Luan, Z., Pervaporation separation of n-heptane/sulfur species mixtures with polydimethylsiloxane membranes, 220-225, Copyright (2008), with permission from Elsevier.)... 

Korkmaz S, Salt Y, Hasanoglu A, Ozkan S, Salt I and Dincer S (2009), Pervaporation membrane reactor study for the esterification of acetic acid and isobutanol using polydimethylsiloxane membrane , Appl Catal A-Gen, 366,102-107. 

Izak, P. Friess, K. Hynek, V. Ruth, W. Fei, Z. Dyson, J. P. Kragl, U. (2009). Separation properties of supported ionic liquid-polydimethylsiloxane membrane in pervaporation process. Desalination, 241,182-187, ISSN 0011-9164. 

D. Hofmann, J. Ulbrich, D. Fritsch and D. Paul. Molecular dynamics simulations of the transport of water-ethanol mixture through polydimethylsiloxane membranes. Polymer 38, 1997,1035. 

Molinari R, Poerio T and Argurio P (2006), Preparation, characterisation and reactivity of polydimethylsiloxane membranes for selective oxidation of benzene to phenol . Desalination, 200,673-675. 

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