Dextran anion exchangers

Dextran anion exchangers modified with lipophilic substituents were active catalysts for cyanide and iodide displacements on 1-bromoalkanes95). The catalyst structures 21-23... 

Choice of Support. The most commonly used organic support is polystyrene (cross-linked with DVB) in its microp-orous (1-2% cross-linking) form, although it has also been used in its macroporous and popcorn form (Ford et al, 1982 Shan et al.,1989). Various other polymeric catalysts have been used like polyvinylpyridine resins, commercial ion-exchange resins (Arrad and Sasson, 1989), modified dextran anion exchangers (Kise et al, 1981), and macroporous glycidyl methacrylate-ethylene dimethacrylate resins (Hradil and Svec,... 

Kise,H., K. Araki, and M Seno, Phase Transfer Catalysis of Modified Dextran Anion Exchangers, Te/r. Letf., 22,1017 (1981). 

The tetrakis-sulphoxides (67) have been reported as a new type of PT catalyst in a solid-liquid mode, for example in 5n reactions of 1-bromo-octane. Nucleophilic substitutions of 1-bromo-octane and benzyl bromide are again the test reactions in a report on the use of the sucrose-ethylene oxide adducts (68a) as PT catalysts in both solid-liquid and liquid-liquid modes. The methacrylate ester derivative (68b) has been polymerized to a cross-linked gel that acts in a TC capacity for the same reactions. In a related approach some modified dextran anion exchangers carrying lipophilic substituents, such as the modified hydroxypropylated dextran gel shown in (69), have been synthesized and shown to catalyse displacement reactions including the alkyl bromide to iodide transformation under TC conditions. ... 

TSK-DEAE-5PW(weak anion exchange, 5 /i particles) Carboxymethyl dextrans Alkaline phosphatase from E. coli periplasmic space proteins 36... 

Matrex PAE-300 (silica based, polyethyleneimine coated weak anion exchange, 10 fi particles) dextran sulfate (MW 5-500 kD), polyvinyl sulfonic acid (MW 2kD) /3-lactoglobulins A and B 30, 31... 

Waters Q-8HR (strong anion exchange, 8 (jl particles) and DEAE-8HR(weak anion exchange, 8 fi particles) Pentosan polysulfate, dextran sulfate /3-lactoglobulins A and B, a-lactalbumin, soybean trypsin inhibitor (STI) 38... 

Gadam, S. D., and Cramer, S. M. (1994). Salt effects in anion exchange displacement chromatography Comparison of pentosan polysulfate and dextran sulfate as displacers. Chromatographia 39, 409-418. 

A method for the introduction of thiol groups into proteins (and polyhydroxylic molecules such as dextran or polyvinyl alcohol) involves adding solid anhydride to a protein solution at pH 7 under nitrogen. Hydrolyzed anhydride is removed with an anion exchanger, salts with a mixed-bed exchanger or by dialysis, and the... 

Plant polyphenols Weakly and medium basic anion exchanger celluloses and poly-dextran Nagels et al. [416]... 

Newer 2-diethylaminoethyl ethers, such as 0-( 2-diethylaminoethyl )-agarose gels," are useful as media for electrophoresis and immunoelec-trophoresis, and the 2-diethylaminoethyl derivative of O-(2-hydroxy-propyl ) cross-linked dextran (Sephadex LH20) is an effective, lipophilic anion-exchanger. The relative stiffness of the molecular chain of 0-(2-diethylaminoethyl) dextran has been estimated from measurements of viscosity at various ionic strengths, and compared with that of other polysaccharide polycations and polyanions. 0-(2-Diethylaminoethyl) dextran itself is claimed to be toxic." ... 

Chloro-2-hydroxypropyl derivatives of such polysaccharides as cellulose and cross-linked dextran (Sephadex) may be prepared by treatment with epichlorohydrin in boron trifluoride etherate. These 3-chloro-2-hydroxypropylated polysaccharides may, in turn, react with ammonia, or primary, secondary, or tertiary amines, and the resultant derivatives of cellulose and Sephadex LH-20, particularly an 0-[3-(di-butylamino)-2-hydroxypropyl] derivative of the latter, are useful anion-exchangers. In the amination procedure, between 50 and 100% of the chlorine atoms are utilized, except in the reaction with tertiary... 

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