Soluble polymer approach

Irradiation at >320 nm releases from the polymer, whether insoluble or water-soluble, free oligosaccharides in very high yields. A simple illustration of such a sequence carried out with either insoluble 2-aminoethyl-substituted poly(acrylamide) beads or with water-soluble, substituted poly(vinyl alcohol) is presented in Scheme 9 the isolated overall yield of lactose was 29.9% (soluble-polymer approach). The synthesis on light-sensitive polymers facilitates the isolation of products, which is important from the preparative point of view and as a tool for the study of enzymes, permitting efficient comparison of acceptor specificity and being capable of demonstrating de novo synthesis. 

Hori, M. Janda, K. D., A Soluble Polymer Approach to the Fishing Out Principle Synthesis and Purification of 8-Amino Alcohols /. Org. Chem. 1998, 63,889. 

Reported applications of the technique to combinatorial syntheses include libraries of peptides ([69,71,72]), 4-amino-benzenesulfonamides ([69,71,72]), and peptidomimetics (poly-a-aza-amino acids or azatides, [69,71,73]). The latter synthesis also illustrates one of the advantages of the soluble polymer approach over solid-phase synthesis, namely. 

This section describes some of the advantages and disadvantages of potential EOR polymers. Moreover, the desired properties of an ideal EOR polymer are described. Some of these water soluble polymers approach... 

Tractable polymers can be prepared when amino and anhydride functions are not located on the same aromatic ring, and different strategies were employed to obtain soluble polymer. AB benzhydrol imide was prepared by polycondensation of 4-(3-amino-l-hydroxymethylene) phtlialic acid monomethyl ester in NMP. The polymer soluble in NMP has been used as adhesive and coating.56 A second approach was based on an ether imide structure. AB aminophenylether phthalic acids (Fig. 5.34) were prepared by a multistep synthesis from bisphenols.155 The products are stable as hydrochloride, and the polycondensation takes place by activation with triphenylphosphite. The polymers are soluble in an aprotic polar... 

In contrast to bulk polymerization, solution polymerization provided soluble polymers with high molecular weights using low FeCl3 concentration at 120-140 C.31 A major disadvantage of the above approaches is that all the metal-halide catalysts need to be removed, since the catalyst residue will deteriorate die thermal stability and electrical and other properties. 

Several soluble precursor approaches were reported to produce high-molecular-weight soluble precursors, which could be later reacted to remove the solubilizing groups. The introduction of bulky substitutions can reduce crystallinities or even suppress crystallization of a polymer, thereby improving its solubility substantially. Thus, the incorporation of removable substituents provides a strategy for... 

Soluble support-based synthetic approaches offer the advantages of both homogeneous solution-phase chemistry (high reactivity, ease of analysis) and solid-phase synthesis (large excess of reagents, simple product isolation and purification) [98,99]. As a representative example, PEG, one of the most widely used soluble polymers, has good solubility in most organic solvents (i.e., dichloromethane, acetonitrile, dimethylformamide, and toluene), but it... 

In 2004, Weberskirch and co-workers tried a new approach by synthesising [RhBr(COD)(NHC)] 23 (NHC = l-(2 -hydroxyethyl)-3-methylimidazolidine-2-ylidene) [28]. Subsequently, attaching the unsymmetrical, monohydroxy-functionalised NHC by ester groups to an amphiphilic, water-soluble polymer support (ps)... 

Barth, H., A practical approach to steric exclusion chromatography of water-soluble polymers, ]. Chromatogr. Sci., 18, 409, 1980. 

Another palladium-catalyzed coupling reaction that has been successfully performed on soluble polymers is the Sonogashira coupling. Xia and Wang have presented an approach in which the PEG 4000 utilized simultaneously serves as polymeric support, solvent, and phase-transfer catalyst (PTC) in both the coupling and... 

Hiller and Funke extensively investigated the change of the polymer structure as a function of the monomer and the initiator concentration in various solvents [231]. The content of pendant vinyl groups in the polymer was about 100% for n-BuLi concentrations below 2 mol % and for the whole range of the monomer concentration studied (20-100 g/1). The content of pendant groups decreased when the n-BuLi concentration increased and approached 80% in the transition region of a soluble polymer to a macrogel. As seen in Fig. 45, the decrease of pen-... 

Scheme 1.6 The first approaches to oligosaccharide synthesis employing soluble polymer supports.

Hildebrand developed solubility parameters to predict the solubility of nonpolar polymers in nonpolar solvents. The solubility parameter is the square root of the CED. For polar solvents, special solvent-polymer interactions can be incorporated into the solubility parameter approach. 

Though CPE has many advantages [10], some problems remain to be solved such as (1) limited number of surfactants, (2) high cloud-point, and (3) strong hydrophobic nature. In an attempt to overcome some of these limitations, Tani et al. [281] proposed a new method that involves solubilization of hydrophobic membrane proteins into aqueous micellar solutions of alkylglucosides, followed by phase separation induced by the addition of a water-soluble polymer such as poly(ethylene)glycol (PEG) and dextran T-500. Using this approach they could carry out the whole procedure from solubilization to phase separation at 0 °C. 

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