Design and introduction of quaternary ammonium hydroxide-functionalized graphene oxide quantum dots as a pseudo-homogeneous catalyst for epoxidation of α,β-unsaturated ketones.

In present work, design and synthesis of a novel pseudo-homogeneous catalyst is described. For this purpose, amine-functionalized graphene oxide quantum dots (N-GOQDs) were prepared from graphene oxide (GO) by a facile one-step oxidative fragmentation approach. The prepared N-GOQDs were then modified with quaternary ammonium hydroxide groups. Various characterization techniques clearly revealed that the quaternary ammonium hydroxide-functionalized GOQDs (N-GOQDs/OH-) have been successfully synthesized. TEM image revealed that the GOQDs particles are almost regularly spherical in shape and mono-dispersed with particle sizes < 10 nm. The efficiency of the synthesized N-GOQDs/OH- as a pseudo-homogeneous catalyst in epoxidation of α,β-unsaturated ketones in the presence of aqueous H2O2 as an oxidant at room temperature was investigated. The corresponding epoxide products were obtained in good to high yields. This procedure has the advantages of a green oxidant, high yields, involvement of non-toxic reagents and reusability of the catalyst without discernible loss in activity.