Antioxidative activity schiff bases

Catalytically active metallic ions may play an important role in ageing of polymers. Their effect may become evident also in transformations of an antioxidation system. From this standpoint, data149 dealing with oxidative transformation of 2,6-di-tert-butyl-4-alkylphenols in the presence of Co(II) complexes of Schiff bases are interesting. The mixture of compounds which results in this case contains 2,6,2, 6 -tetra-tert-butyl-4,4 -dioxycyclohexadiene-l-one XCVIII and compounds formed by its cleavage, among them 2,6-di-tert-butyl-4-hydroxy-4-alkyl-2,5-cyclohexadiene-l-one of the type CX, 2,6-di-tert-butyl-l,4-benzoquinone XXII, and 3,5,3, 5 -tetra-tert-butyl-4,4 -diphenoquinone XX. 

Five kinds of Schiff bases of chitosan and carboxymethyl chitosan (CMTS) have been prepared, and their respective antioxidant effect was dependent on contents of active hydroxyl and amino groups in molecular chains (Guo et al. 2005). 

Guo, Z., Xing, R., Liu, S. et al. 2005. The synthesis and antioxidant activity of the Schiff bases of chitosan and carboxymethyl chitosan. Bioorg. Chem. Lett. 15 4600-4603. 

---