Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Patent
1992-09-25
1994-10-18
Nagumo, Mark
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
536103, 526207, C08F 2400
Patent
active
053570120
DESCRIPTION:
BRIEF SUMMARY
The invention relates to water-insoluble cyclodextrin bead polymers, which are formed by free radical polymerization of cyclodextrin derivatives containing polymerizable groups, and to processes for their preparation.
Cyclodextrins are cyclic, non-reducing oligosaccharides, consisting of .alpha.-D-glucose units which have exclusively 1,4-glucoside links. Currently .alpha.-, .beta.- and .gamma.-cyclodextrin, which are built up from 6, 7 and 8 anhydroglucose units respectively, are available in relatively large amounts. The most interesting property of the cyclodextrins is their ability to form inclusion complexes (host/guest compounds). In these compounds hydrophobic guest molecules of suitable size are enclosed in the cyclodextrin cavity and reversibly bonded by hydrophobic interactions, van der Waals forces and, in some cases, also hydrogen bridge bonds. By far the majority of applications of cyclodextrins are also based on the formation of these inclusion complexes. Thus, for example, they are suitable for chromatographic separations, as catalysts, as stabilizers, for solubilization or for converting liquid substances into the solid aggregate state.
Since, because of their chiral C atoms, cyclodextrins are able to act as enantion-selective receptors, chromatographic separations of suitable enantiomers are also possible with the participation of cyclodextrin inclusion compounds. As a result of these selective receptor characteristics, the stereoselectivity of chemical reactions can also be increased by cyclodextrins. However, if dissolved cyclodextrin is used as separating agent or extractant or as a catalyst, the separation of the inclusion compound from the system and the liberation of the included compound from the cyclodextrin are difficult. Therefore, an immobilization of cyclodextrins with the production of their inclusion capacity is advantageous. Immobilized cyclodextrins can be used, for example, as the stationary phase in separation processes in chromatography. Hitherto, an immobilization of cyclodextrins has been attempted in very diverse ways. However, all previously described immobilization methods have defects.
Insoluble (immobilized) cyclodextrins and their use in separation processes have already been described by Solms and Egli (Helv. Chim. Acta 48, 1225 (1965)). In German Patent Specification DE 29 27 733, J. Szejtli et al. describe cyclodextrin-polyvinyl alcohol polymers and a process for their preparation. Compared with the cyclodextrin gels known hitherto, these have somewhat better mechanical properties.
In J. Food Sci. 48, 646, (1983), P. E. Shaw and C. W. Wilson describe the use of such cyclodextrin polymers for separating bitter substances from citrus juices.
In Gordian 89 (3), 43 (1989) A. Ujhazy and J. Szejtli also describe the separation of a bitter substance (naringin) from aqueous solutions with the aid of a cyclodextrin bead polymer.
In the case of the already known cyclodextrin gels which have been mentioned, the immobilization of the cyclodextrins is achieved by bifunctional crosslinking agent units. A three-dimensional, hydrophilic cyclodextrin lattice which is swellable in water is formed. Material in bead form can be obtained by means of a method relating to inverse suspension polymerization. The crosslinking agent units used are preferably epichlorohydrin or diepoxy compounds. However, all the cyclodextrin polymers prepared in this way which have been described hitherto are unsuitable for filling columns which are operated under a pressure distinctly higher which are operated under a pressure distinctly higher than atmospheric pressure, since even under a pressure of 3 bar there is already a deformation of the packing such that the flow rates through a filled column are low. Moreover, when the pressure is increased, the flow-through rates do not increase substantially because of the softness of the material. High flow-through rates are, however, desirable on economic grounds. Furthermore, an increase in the separation efficiency can also be achieved by increasing the p
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P. E. Shaw et al., J. Food Sci. 48(1983), 646, "Debittering Citrus Juices with beta-Cyclodextrin Polymer".
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Kreuzer Franz-Heinrich
Nussstein Peter
Schmitt-Sody Wolfgang
Staudinger Guenther
Consortium fur Elektrochemische Industrie GmbH
Nagumo Mark
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