Cellulose, (1f4)--D-glucopyranan, was for the first time synthesized by cationic ring-opening polymerization of 3,6-di-O-benzyl-R-D-glucose 1,2,4-orthopivalate (5) into 3,6-di-O-benzyl-2-O-pivaloyl--D-glucopyranan (6) and subsequent removal of the protective groups. Polymerization of the orthoester 5 by triphenyl carbenium tetrafluoroborate gave 3,6-di-O-benzyl-2-O-pivaloyl--D-glucopyranan with [R] D -37.2°and a number-average molecular weight of 8.3 × 10 3 (DP n ) 19.3). Removal of the pivaloyl and benzyl groups and subsequent acetylation gave acetylated (1f4)--D-glucopyranan which was completely identical with cellulose triacetate (CTA) prepared from low molecular weight cellulose. The synthesized CTA was converted by deacetylation to cellulose, which has the cellulose-II crystal structure.

Demethylation of guaiacyl-type synthetic lignin (GDHP) with three different reagents, 1-dodecanethiol (DSH), hydroiodic acid (HI), and iodocyclohexane (ICH), was investigated as a basic study for lignin functionalization. Demethylation did not proceed efficiently in the reaction with DSH, although cleavage of the lignin side chains and nucleophilic substitution by DSH occurred. Demethylation proceeded efficiently in the reactions with HI and ICH, with significant cleavage of the lignin side chains. Furthermore, a recondensation reaction also occurred in the reaction with ICH. As a result, ICH was found to be the most effective demethylation reagent for increasing the phenolic-OH levels in the synthetic lignin. GDHP demethylated with ICH showed higher tannin-like properties (bovine serum albumin adsorption, 2,2-diphenyl-1-picrylhydrazyl radical scavenging, and iron(III) binding abilities) than nondemethylated GDHP. The latter two abilities especially were significantly improved. In addition, it was found from preliminary experiments that the demethylated GDHP was a useful precursor for lignin-based epoxy resin. These results suggested that chemical demethylation is an effective method for the functionalization of lignin.

Prion diseases are fatal, progressive, neurodegenerative diseases caused by prion accumulation in the brain and lymphoreticular system. Here we report that a single subcutaneous injection of cellulose ethers (CEs), which are commonly used as inactive ingredients in foods and pharmaceuticals, markedly prolonged the lives of mice and hamsters intracerebrally or intraperitoneally infected with the 263K hamster prion. CEs provided sustained protection even when a single injection was given as long as one year before infection. These effects were linked with persistent residues of CEs in various tissues. More effective CEs had less macrophage uptake ratios and hydrophobic modification of CEs abolished the effectiveness. CEs were significantly effective in other prion disease animal models; however, the effects were less remarkable than those observed in the 263K prion-infected animals. The genetic background of the animal model was suggested to influence the effects of CEs. CEs did not modify prion protein expression but inhibited abnormal prion protein formation in vitro and in prion-infected cells. Although the mechanism of CEs in vivo remains to be solved, these findings suggest that they aid in elucidating disease susceptibility and preventing prion diseases.

The direct anodic oxidation of non-phenolic lignin model compounds was investigated to understand their basic behaviors. The results of cyclic voltammetry (CV) studies of monomeric model, such as 1-(4-ethoxy-3-methoxyphenyl)ethanol, are interpreted as the oxidation for C a -carbonylation did not proceed in the reaction without a catalyst, but a base promotes this reaction. Indeed, the bulk electrolyses of the monomeric lignin model compounds with 2,6-lutidine afforded the corresponding C a -carbonyl compounds in high yields (60-80%). It is suggested that deprotonation at C a -H in the ECEC mechanism (Eselectron transfer and Cschemical step) is important for C a -carbonylation. In the uncatalyzed bulk electrolysis of a b-O-4 model dimeric compound, 4-ethoxy-3-methoxyphenylglycerol-b-guaiacyl ether, the corresponding C a -carbonyl compound was not detected but as a result of C a -C b cleavage 4-O-ethylvanillin was found in 40% yield. In the electrolysis reaction in the presence of 2,6-lutidine (as a sterically hindered light base), the reaction stopped for a short time unexpectedly. These results indicate the different electrochemical behavior of simple monomeric model compounds and dimeric b-O-4 models. The conclusion is that direct electrooxidation is unsuitable for C a -carbonylation of lignin.

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