Ultrasonicated, Nano-ZnO Catalyzed Green Synthesis of α-Hydroxyphosphonates and their Antioxidant Activity

Abstract

A green method was developed for the synthesis of 12 α-hydroxyphosphonates 3a-l through the Pudovik reaction of diethyl phosphite (2) and aromatic/heterocyclic aldehydes 1a-l under sonication and conventional conditions using ZnO nano sheets as a catalyst. The advantages of this protocol are high yields, high purity of the desired products, short reaction times, easy workup, and reusability of the catalyst. The structure of the catalyst, ZnO nano sheets, was elucidated by EDS, TEM, XRD, and IR and the title compounds were characterized by spectral data (IR, 1 H, 13 C, 31 P NMR, and mass spectrometry) and elemental analysis. The title compounds were screened for their radical scavenging activity employing DPPH, H 2 O 2 methods and IC 50 values also determined. Compounds 3i, 3j, 3k, and 3l were exhibited promising antioxidant activity almost equal to standard BHT.