Structure of a cellulose I–ethylenediamine complex

The structure of a crystalline cellulose I–ethylenediamine complex has been determined by x‐ray diffraction methods as part of an investigation of cellulose–solvent interaction. The complex studied is that formed when native ramie fibers are swollen in ethylenediamine and then vacuum‐dried. The unit cell is monoclinic with dimensions a = 12.87 Å, b = 9.52 Å, c = 10.35 Å, and γ = 118.8°, and it contains disaccharide segments of two chains, with one ethylenediamine per glucose residue. The refined model contains parallel cellulose chains that are linked by hydrogen‐bonded ethylenediamine molecules. The chains along the b‐axis are packed in register, leading to stacks of chains analogous to those in chitin. All the hydroxyl groups are satisfactorily hydrogen‐bonded and each ethylenediamine forms four donor and two acceptor hydrogen bonds. From this work it can be seen that the interaction of cellulose I with ethylenediamine involves scission of the intermolecular hydrogen bonds followed by disruption of the stacks of quarter‐staggered chains.