Monomer synthesis saccharides

For the synthesis of carbohydrate-substituted block copolymers, it might be expected that the addition of acid to the polymerization reactions would result in a rate increase. Indeed, the ROMP of saccharide-modified monomers, when conducted in the presence of para-toluene sulfonic acid under emulsion conditions, successfully yielded block copolymers [52]. A key to the success of these reactions was the isolation of the initiated species, which resulted in its separation from the dissociated phosphine. The initiated ruthenium complex was isolated by starting the polymerization in acidic organic solution, from which the reactive species precipitated. The solvent was removed, and the reactive species was washed with additional degassed solvent. The polymerization was completed under emulsion conditions (in water and DTAB), and additional blocks were generated by the sequential addition of the different monomers. This method of polymerization was successful for both the mannose/galactose polymer and for the mannose polymer with the intervening diol sequence (Fig. 16A,B). 

Another important discovery in the area of combinatorial synthesis with di- and tri-saccharides was made by Kahne and co-workers at Princeton [4c]. Kahne s approach utilized solid phase technology to synthesize a saccharide library (Scheme 3), which was especially challenging since, in order for a solid phase approach to be successful, bonds between monomers must be formed in high yields. This is not trivial since most high-yielding coupling reactions in carbohydrate chemistry are not general in nature [5]. 

The same procedure of catalyst synthesis applied to other polysaccharides, such as -carrageenan and chitosan, allowed data on the influence of the chemical structure of the support to be obtained. The differences in turnover numbers (moles of product per moles of Pd per hour), close to 500 for alginates, 190 for carrageenan, and only 40 for chitosan, indicated that the activities were correlated to the electrostatic properties of the support. Carrageenans only bear one sulfate group per two saccharide monomers, while alginate presents one carboxylic group... 

Two striking differences distinguish the essence of this chapter from most other chapters, namely (i) the fact that the furan compounds relevant to polymer synthesis are not found as such in nature but are instead obtained from parent renewable resources and (ii) it is possible in principle to envisage a whole new realm of polymer materials based on furan monomers and furan chemistry, covering a very wide spectrum of macromolecular structures. Concerning the first point, the massive availability of saccharidic precursors and their relatively sirt5)le conversion into furan derivatives, eliminate in fact any apparent problem of absence of such natural structures. As for the second point, its unique relevance has to do with the potential perspective of a viable alternative to the present reality based on polymer chemistry derived from fossil resources. In other words, the biomass refinery concept would be applied here to the synthesis of different furan monomers, simulating the equivalent petroleum counterpart. 

Macromolecule is a general name for a very large molecule. A high polymer is a macromolecule. A polymer produced by chemical synthesis is usually made from a limited number of repeating units, or monomer units. Polypeptides produced by chemical synthesis are made from amino acids. Proteins that are produced by biosynthesis contain mainly amino acids and may contain a few saccharidic or lipidic units. 

Similarly, self-doped PABA can be prepared using excess of saccharide and one equivalent of fluoride to monomer. Complexation between saccharides and aromatic boronic acids is highly pH dependent, presumably due to the tetrahedral intermediate involved in complexation [25]. Because the pKa of 3-aminophenylboronic acid is 8.75, complexation requires pH values above 8.6. This pH range is not compatible with the electrochemical synthesis of polyaniline, which is typically carried out near a pH value of 0. However, Smith et al. have shown that the addition of fluoride can stabilize the complexation of molecules containing vicinal diols with aromatic boronic acids [23]. Based on this work, it was postulated that the electrochemical polymerization of a saccharide complex with 3-aminophenylboronic acid in the presence of one molar equivalent of fluoride at pH values lower than 8 is possible if a self-doped polymer is produced in the process. 

Dane, E.L., and M.W. Grinstaff. 2012. Poly-amido-saccharides synthesis via anionic polymerization of a p-lactam sugar monomer. Journal of the American Chemical Society 134 (39) 16255-16264. 

Saccharides have a number of attributes that make them very attractive as raw materials for the synthesis of polymers. The confluence in saccharides of different functionalities such as multiple hydroxyl groups and latent reactivity, which is difficult to realize in wholly synthetic materials, is of particular interest to us. The preparation of monomers derived from saccharides and the subsequent polymerization of these materials is one approach that has been extensively pursued as a means to introduce saccharide groups into synthetic polymers (1-9). With a few exceptions (2), most of this previously reported work has involved attaching a polymerizable moiety onto a mono- or disaccharide. The practical synthesis of a new family of monomers derived from carbohydrates ranging from monosaccharides to large oligosaccharides and the use of these monomers to produce a detectable water treatment polymer are described in this paper. 

A very practical and broadly applicable two-step synthesis of a new family of monofunctional saccharide monomers was developed (16). In this synthesis, all reactions are done in water, no protecting groups are employed, and no by-products are formed. These saccharide-derived monomers were found to be useful as tags for water treatment polymers (7 7). 

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