MERCERIZATION OF CELLULOSE .5. CRYSTAL AND MOLECULAR-STRUCTURE OF NA-CELLULOSE .1.

The crystal structure of Na-cellulose I, a NaOH-cellulose complex formed by treating cellulose I with aqueous NaOH, has been investigated by X-ray diffraction analysis combined with stereochemical modeling. The structure crystallizes in a four-chain unit cell dimensions a = 8.83 angstron, b = 25.28 angstron c (fiber axis) = 10.29 angstrom, and all angles 90-degrees. The probable space group is P2(1). The unit cell contains eight anhydroglucopyranose residues, eight Na+ ions, and an undetermined amount of water. For the most likely composition, C6H10O5.NaOH.2H2O, the calculated density rho-c = 1.38 g/cm3. An antiparallel arrangement of chains is slightly favored over a parallel one. The chain conformations of the most probable structure differ in the rotational positions of the O(6) hydroxyls: tg in the "up" chains and gt in the "down" chains. All eight Na+ ions form secondary ionic bonds with O(2) and O(6) hydroxyls, but not with the O(3) hydroxyls.