Peculiar behavior of starch 2,3-dialdehyde towards sulfanilamide and sulfathiazole

• Synthesis of two novel Schiff's base.
• Difference in reactivity aldehyde starch and aldehyde cellulose towards Schiff base formation.
• Starch aldehyde reactivity comparison towards sulfanilamide and sulfathiazole.

In this study, starch (1) was oxidized to starch-2,3-dialdehyde (DAS; 2) using potassium periodate. In addition, two novel Schiff’s bases (5 & 6) were synthesized via a condensation reaction between DAS (2) and sulfa drugs (sulfanilamide; 3 & sulfathiazole; 4). The synthesized Schiff’s bases (5 & 6) were characterized by FT-IR spectroscopy, X-ray diffraction and DSC analysis. DAS can easily be oxidized owing to its high aldehyde content (91.0%). However, it has low reactivity towards sulfanilamide (3) and sulfathiazole (4). According to the diffraction functional theory, this peculiar behavior is caused by the absence of V-shape in α−glucan linkage in DAS molecules, making the carbonyl group least electropositive. This reduces the nucleophilic attacks of the amino group in sulfa drugs towards the carbonyl group in DAS.