| Abstract: | A reduced unit cell derived from the presently accepted unit cell and a new parallel chain arrangement is proposed for cellulose II (regenerated cellulose). In the present structure, all the cellulose chains are identical and there is only one chain passing through each unit cell. The intensity data for all reflections with d spacings greater than 1.747 Å have been calculated and were found to be in good agreement with the corresponding observed x-ray intensities. The calculated agreement factor is R = 0.50. Two intrachain hydrogen bonds parallel to the fiber axis and one interchain hydrogen bond perpendicular to the fiber axis stabilize the structure. The hydrogen bonding network is in fair agreement with infrared dichroic data, and the chain arrangement conforms to stereo-chemical criteria. No short contacts are observed. The parallel chain is also compatible with the structure of cellotetraose and the accepted hypothesis of cellulose biosynthesis, as well as the latest parallel structure for Valonia. |
