Cyclic systems, cellulosics

An overview of cellulose-based chemicals and fuels systems is presented in Figure 1. In this cyclic system, demand for fuels and chemicals leads to the organization of factors of production (land, labor, capital, etc.) for the generation of biomass for use as a renewable resource. The plant culture activity is called silviculture if trees are the desired biomass or agriculture if herbaceous plants are grown... 

Compound 9, which Is not detectably rehydrated by water or attacked by simple alcohols, Is also converted In high yield to cyclic acetals H at 70 C, pointing again to the significant thermodynamic driving force of cyclic acetal formation. This strongly favored acetal reaction Is one explanation for the excellent adhesion performance of this system on cellulosics and glass. 

Heinze et al. found that DMSO in combination with tetrabutylammonium fluoride trihydrate dissolved cellulose (degree of polymerization < 650) within 15 min at room temperature [38]. They also demonstrated that homogeneous esterification of cellulose is possible in this solvent system. The applicability of this new solvent system to cellulose grafting has recently been proved by adoption of cyclic compounds such as lactones and N-carboxy a-amino acid anhydrides (NCAs) [39]. e-Caprolactone was facilely graft-polymerized on cellulose at a graft rate of 65% (per trunk weight of 100), and NCAs at over 100%, in the respective homogeneous reaction systems at < 60 °C. 

The properties of spinach chloroplasts adsorbed onto diethylaminoethyl-cellulose have been reported and the immobilized chloroplasts used for the continuous photoreduction of 2,6-dichloroindophenol as an indicator of photosystem II activity in the chloroplasts. The formation of ATP from ADP and orthophosphate via the cyclic photophosphorylation system has been achieved using chloroplasts copolymerized with polyvinylalcohol onto an electrode. Citrobacter freundii cells immobilized by co-casting with collagen have been used in a flow type sensor for cephalosporins. ... 

Cyclic anhydrides like acetic, phthalic, and succinic anhydride have been widely used in cellulose modifications to produce different cellulose derivatives such as cellulose acetate, cellulose butyrate, cellulose benzoate, cellulose phthalate, and cellulose with or without catalyst, which have several applications such as water absorbents for soil in agriculture, drug delivery system, and as thermoplastic. 

Aloni Y, Delmer D.P., and Benziman M. 1982. Achievement of high rates of in vitro synthesis of 1, 4-beta-D-glucan activation by cooperative interaction of the Acetobacter xylinum enzyme system with GTP, polyethylene glycol, and a protein factor. Proc Natl Acad Sci USA 79(21) 6448-6452. Amikam D. and Benziman M. 1989. Cyclic diguanylic acid and cellulose synthesis in Agrobacterium tumefaciens. J Bacterid 171(12) 6649-6655. 

It should also be noted that some nonradical ionic and condensation reactions of monomers with cellulose are used to modify the properties of cellulosic products. In one type of anionic-initiated reaction of monomers, cellulose is reacted with concentrated aqueous solutions of alkali metal hydroxides to yield cellulose copolymer. Free alkali metal in liquid ammonia or alkali metal alkoxides in nonaqueous systems may also be used as initiators of cellulose alkoxide derivatives. In cationic-initiated formation of copolymers, cellulose is reacted with an acid, such as boron trifluoride, to yield a cellulosic carbonium ion which initiates reactions with vinyl monomers. Condensation reactions of cyclic monomers with cellulose also form copolymers. Cellulose is usually slightly oxidized and also has reactive hydroxyl groups on carbons C-2, C-3 and C-6 of the anhydroglucose unit. The reactions of cyclic monomers are initiated at these carbonyl groups. A heating step may increase cellulosic oxidation and thereby increase the yield of these condensation products of cellulose and cyclic monomers." ... 

---