Cyclodextrins preparation

Darrouzet H. Preparing cyclodextrin inclusion compounds. Manuf... 

Rohrbach, RP (1990). Method of preparing cyclodextrin-coated surfaces. US Patent 4917956. 

The use of cyclodextrins in the cosmetic industry is very similarly widespread. Most vitamins form stable complexes with cyclodextrins. These complexes have been found to increase the bioavailability of compounds such as vitamin A and retinol. The added advantage is the protection of vifamin A and retinol against oxidation. Again, as with the food indusfry, emulsions are easily prepared. Cyclodextrins have also been incorporated into many sun-block lotions. Complex-ation increases the photostability of the cream, increases its protective properties, reduces odour and decreases the staining of fabrics. 

Optical properties of cyanines can be usefiil for both chiral substituents/environments and also third-order nonlinear optical properties in polymer films. Methine-chain substituted die arbo cyanines have been prepared from a chiral dialdehyde (S)-(+)-2-j -butylmalonaldehyde [127473-57-8] (79), where the chiral properties are introduced via the chiral j -butyl group on the central methine carbon of the pentamethine (die arbo cyanine) chromophore. For a nonchiral oxadicarbocyanine, the dimeric aggregate form of the dye shows circular dichroism when trapped in y-cyclodextrin (80). Attempts to prepare polymers with carbocyanine repeat units (linked by flexible chains) gave oligomers with only two or three repeat units (81). However, these materials... 

The type of CSPs used have to fulfil the same requirements (resistance, loadabil-ity) as do classical chiral HPLC separations at preparative level [99], although different particle size silica supports are sometimes needed [10]. Again, to date the polysaccharide-derived CSPs have been the most studied in SMB systems, and a large number of racemic compounds have been successfully resolved in this way [95-98, 100-108]. Nevertheless, some applications can also be found with CSPs derived from polyacrylamides [11], Pirkle-type chiral selectors [10] and cyclodextrin derivatives [109]. A system to evaporate the collected fractions and to recover and recycle solvent is sometimes coupled to the SMB. In this context the application of the technique to gas can be advantageous in some cases because this part of the process can be omitted [109]. 

One of the latest resolutions of the anesthetic enflurane (8) has been performed by preparative GC on a y-cyclodextrin CSP, the process later being scaled-up via SMB [109] (Fig. 1-4). This is the first GC-SMB separation described. 

Inspired by the separation ability of cyclic selectors such as cyclodextrins and crown ethers, Malouk s group studied the synthesis of chiral cyclophanes and their intercalation by cation exchange into a lamellar solid acid, a-zirconium phosphate aiming at the preparation of separation media based on solid inorganic-organic conjugates for simple single-plate batch enantioseparations [77-80]. 

Electrophoretic ally Driven Preparative Chiral Separations using Cyclodextrins... 

Several model systems related to metalloenzymes such as carboxypeptidase and carbonic anhydrase have been reviewed. Breslow contributed a great deal to this field. He showed how to design precise geometries of bis- or trisimidazole derivatives as in natural enzymes. He was able to synthesize a modified cyclodextrin having both a catalytic metal ion moiety and a substrate binding cavity (26). Murakami prepared a novel macrocyclic bisimidazole compound which has also a substrate binding cavity and imidazole ligands for metal ion complexation. Yet the catalytic activities of these model systems are by no means enzymic. 

To circumvent these difficulties, a preparation of water-soluble coelenterazine has been developed (Teranishi and Shimomura, 1997a). The preparation contains coelenterazine and 50-times (by weight) of hydroxypropyl-P-cyclodextrin. To prepare this material, 0.1 ml of 3.0 mM coelenterazine in methanol and 0.2 ml of 45 mM solution of the cyclodextrin are mixed and dried under reduced pressure. The dried residue is extracted with 1.0 ml of lOmM phosphate buffer, pH 7.0, containing 2 mM EDTA (if needed), and the extract (after centrifugation) is again dried under reduced pressure. With this preparation, an aqueous solution containing up to 3 mM coelenterazine can be made. 

Micellar medium has received great attention because it solubilizes, concentrates and orientates the reactants within the micelle core and in this way accelerates the reaction and favors the regio- and stereoselectivity of the process [68], In addition the micellar medium is cheap, can be reused, is more versatile than cyclodextrins and more robust than enzymes. With regard to Diels Alder reactions, we may distinguish between (i) those in which one or both reagents are surfactants which make up the micellar medium, and (ii) those that are carried out in a micellar medium prepared by a suitable surfactant. 

Cyclodextrin solution for extraction studies was prepared at a concentration of 1.00 x 10" iif by dissolving solid y-CDx in deionized water (Continental Water Systems, Atlanta, Georgia). Fresh solution was prepared daily to prevent bacterial growth and CDx decomposition from interfering with complexation and extraction. Cyclodextrin was purchased from Advanced Separation Technologies, Inc. (Whippany, New Jersey) and was used as received. Solid CDx from one lot number was used for all extractions. 

In this study, complexation of A9-THC and cannabidiol (prepared by freeze drying) with randomly methylated b-cyclodextrin and hydroxypropyl-b-cyclodextrin (HP-fi-CD) was studied by the phase-solubiHty method. The aqueous solubility of CBD and THC increased as a function of CD concentration, and the dissolution increased for THC and CBD cyclodextrin complexes significantly in contrast to plain THC and CBD. These results demonstrate that cyclodextrins increased both the aqueous solubility and dissolution rate... 

Enzymatic preparation of radiolabeled linear maltodextrins and cyclodextrins 43... 

There is a wide variety of commercially available chiral stationary phases and mobile phase additives.32 34 Preparative scale separations have been performed on the gram scale.32 Many stationary phases are based on chiral polymers such as cellulose or methacrylate, proteins such as human serum albumin or acid glycoprotein, Pirkle-type phases (often based on amino acids), or cyclodextrins. A typical application of a Pirkle phase column was the use of a N-(3,5-dinitrobenzyl)-a-amino phosphonate to synthesize several functionalized chiral stationary phases to separate enantiomers of... 

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