STEREOREGULAR ACYCLIC POLYALCOHOLS AND POLYACETATES FROMCELLULOSE AND AMYLOSE

Oxidative scission with periodate of all the C(2)-C(3) bonds of the D-glucopyranose rings of cellulose and amylose followed by reduction with borohydride of the resulting polydialdehydes afforded the acyclic polyalcohols RDC and RDA [RDC = poly[(2r,4S,5~)-2,4,5-tris(hydro~ethyl)-l,3-dioxo~n~ethylene]; RDA = poly[ (2s,4S,5R)-2,4,5-tris(hydroxymethyl)-1,3-dioxopentamethylene]T]h. e corresponding triacetates (RDC-Ac and RDA-Ac) were obtained by conventional acetylation of the polyalcohols. The 13C and 'H NMR spectra of the products indicated a high degree of structural homogeneity, with retention of the different configuration at C( 1) of the original polysaccharides. The concept of stereoregularity, and stereoisomerism of polymers obtained from cellulose and amylose, is reflected also by the high crystallinity easily achieved in solid samples, with X-ray powder patterns unambiguously different for pairs of cellulose and amylose derivatives. Light scattering measurements indicate a strong tendency to association for RDC in water, as well as for the corresponding peracetate RDC-Ac in acetone, acetonitrile, and trifluoroethanol. RDA forms microgels in water, while RDA-Ac associates on increasing concentration and/or time in acetone and acetonitrile.