SELECTIVE PERIODATE OXIDATION OF C6-CARBOXYCELLULOSE TO C6-CARBOXY-2,3-DIALDEHYDE CELLULOSE: PROCESS OPTIMIZATION AND STRUCTURAL CHARACTERIZATION

In this study, the selective oxidation of C6-carboxycellulose with sodium periodate (NaIO₄) to obtain C6-carboxy-2,3-dialdehyde cellulose was investigated. The effects of NaIO₄ concentration and reaction duration on the formation of aldehyde groups and product yield were evaluated. Increasing the oxidant concentration and reaction time promoted aldehyde group formation; however, excessive oxidation conditions resulted in a decrease in product recovery. The optimal oxidation conditions were established at 2.5% NaIO₄, pH 3.0-3.5, 25-30 °C, and a reaction time of 20 min. Under these conditions, the aldehyde group content reached 6.0 mmol/g, while the product yield was maintained at 80%. FTIR analysis confirmed the formation of aldehyde-containing structures resulting from selective oxidation of the vicinal hydroxyl groups at the C2 and C3 positions, while XRD analysis revealed a decrease in crystalline ordering and an increase in amorphous regions after oxidation. SEM observations demonstrated pronounced morphological changes, including increased surface roughness, heterogeneous structural features, and partial disruption of the fibrillar organization of cellulose after periodate treatment. Nevertheless, preservation of the general fibrillar framework indicated controlled oxidation without complete destruction of the cellulose structure. The obtained results demonstrate that optimization of periodate oxidation parameters enables the preparation of C6-carboxy-2,3-dialdehyde cellulose with a balanced combination of aldehyde functionality, structural preservation, and potential applicability as a reactive cellulose-based intermediate for further functional material development.

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