Structure of a cellulose II‐hydrazine complex

The structure of a crystalline cellulose II‐hydrazine complex has been determined by x‐ray diffraction methods as part of an investigation of cellulose‐solvent interaction. The complex studied was that formed when Fortisan fibers were swollen in hydrazine and then vacuumdried. The unit cell is monoclinic with dimensions a = 9.37 Å, b = 19.88 Å, c = 10.39 Å, and γ = 120.0° and contains disaccharide segments of four chains, with one hydrazine per glucose residue. In view of the limited x‐ray intensity data, the structure has been determined based on an approximate unit cell containing two chain segments, with a = 4.69 Å, using the linked‐atom least‐squares refinement procedures. The refined model contains antiparallel cellulose chains that are linked by both intermolecular hydrogen bonds and hydrogen‐bonded hydrazine molecules. The parallel chains in the 020 planes are packed in register, leading to stacks of chains analogous to those in chitin. All the hydroxyl groups are satisfactorily hydrogen‐bonded, and each hydrazine forms four donor and two acceptor hydrogen bonds, including an NH…N bond between hydrazines. From this work it can be seen that the interaction of cellulose II with hydrazine involves scission of the intermolecular hydrogen bonds followed by disruption of the stacks of quarter‐staggered chains. The latter effect is probably necessary for hydrazine to act as a cellulose solvent.