Synthesis of potential antioxidants by synergy of ultrasound and acidic graphene nanosheets as catalyst in water.

Efficient synthesis of a set of bisphenolic compounds, resulting from the incorporation of 2,4-dialkylphenols and aromatic or aliphatic aldehydes, allowed the discovery of new bisphenols with relative modest to good antioxidant activity. Bisphenolic compounds were prepared via easy and simple approach under ultrasound irradiation in water. Sulfonated graphene nanosheets were employed as a catalyst for the synthesis of bisphenolic compounds. These compounds were obtained in high to excellent yields (88-98%) and relatively short reaction times (4-20 min). Moreover, some of the synthetic compounds were investigated and revealed outstanding antioxidant activity, when examined by a 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) decolorization assay system. The proposed method has a novel viewpoint in the preparation of potential antioxidant compounds.