Role of Degree of Oxidation of Graphene Oxide on Biginelli Reaction Kinetics

摘要

The effect of varying degree of oxidation of graphene oxide on its catalytic activity for synthesis of dihydropyrimidinones via Biginelli reaction is investigated. Graphene oxide with varying degree of oxidation (GO-x) was synthesized, and characterized to confirm the change in functional groups on GO surface with different amount of oxidizing agent used during synthesis. An increase in amount of oxidant, increases the percentage of oxygen in GO-x, increasing the d-spacing and thus enhancing the exfoliation of GO-x. The carboxylic acid groups increase with increasing oxidation degree, while the proportion of hydroxyl groups is almost the same. GO-x shows excellent activity towards catalysing Biginelli reaction. An increase in oxygen content in GO-x improves its catalytic activity, which is attributed to the increased acidity in GO-x. Reaction kinetics imply a second order reaction. GO-x shows excellent recyclability with only marginal loss in activity on recycle.