Preparation and polymer-analogous reactions of a poly(vinyl sugar) with a C-C bond between sugar and polymer backbone

The synthesis of a new type of poly(vinyl sugar) is described whose polymer backbone is connected with the monosaccharide unit by a C-C bond. Such polymers can be obtained by radical initiation. They show good stability in polymer-analogous reactions in contrast to common poly(vinyl saccharides) whose sugar residues are bound to the polymeric chain by ester, ether, or glycoside bonds. Starting from 7,8-dideoxy-1,2;3,4-di-O-isopropylidene-alpha-D-galacto-oct-7- en-1,5-pyranos-6-ulose (1) polymers (P1) could be obtained by emulsion polymerization in high yields. Reduction of the keto group of P1 proceeded quantitatively and yielded poly(7,8-dideoxy-1,2;3,4-di-O-isopropylidene-D,L- glycero-alpha-D-galacto-oct-7-en-1,5-pyranose) (P3). In contrast to the following polymers without protecting groups these poly(vinyl ketones), which were soluble in tetrahydrofuran and toluene, did not follow a pure GPC-separation mechanism. The protecting groups of the poly(vinyl saccharides), either with or without keto groups, could be removed completely to give P2 and P4. The solubility of the polymers P2 with galac tose-functionalized side chains in water was limited to a weight-average molecular weight (M) over bar(w), of 1 500 000 due to association phenomena of the monosaccharide units. Reduction of the hemiacetal group and of the keto group of P2 yielded poly(1,2-dideoxy-D,L-glycero-D-galacto-oct-1-enitol) (P5) with sugar alcohol side chains instead of a cyclic monosaccharide unit. Oxidation of the hemiacetal group of P2 and P4 furnished poly(7,8-dideoxy-D-galacto-oct-7-en-6-ulsonic acid sodium salt) (P6) and poly(7,8-dideoxy-D,L-glycero-D-galacto-oct-7-enonic acid sodium salt) (P7), respectively. These polymers showed very high viscosities because of their polyelectrolyte character.