Dialdehyde cellulose is cellulose whose anhydroglucose units carry two aldehyde groups at C2 and C3, produced by oxidative cleavage of the vicinal diols of the glucopyranose ring ^[1]. Cleavage opens the ring, so the product is a chain of 2,3-dialdehydic residues whose aldehyde content is expressed per anhydroglucose unit ^[1]. Because the aldehydes hydrate and form hemiacetals with neighbouring hydroxyls, the polymer is partly crosslinked and its crystallinity falls as oxidation proceeds ^[2]. The dialdehyde groups condense with amines and hydrazides to give imines and hydrazones, and that reactivity separates the material from carboxymethyl or hydroxyethyl cellulose ^[3]. Over-oxidation shortens the chain and introduces carboxyl groups ^[3].