Development of Green Chemical Process: The Reaction of Condensation in a Continuous Flow Microreactor System

Abstract

Aromatic heterocyclic compounds containing nitrogen in their structure have attracted considerable interest in medicine, because of their certain pharmacological properties including anticancer, anti-inflammatory, antihypertensive, antibacterial, antifungal and antiviral activities. Among them, derivatives with 2-pyridone moiety are particularly notable due to their wide application in pharmacological and dye industry. A usual procedure for synthesis of 2-pyridone moiety is classic condensation reaction of 1,3- dicarbonyl compounds with cyanoacetamide. However, in the case of various substituted reactants, drawback of this reaction can be a low yield of desirable products and long reaction time. This factor has led to the development of different methods for synthesis in order to overcome these defects. The microreactor technology and flow chemistry could play a significant role in the improving of organic synthesis efficiency. The microreactor approach could provide enhanced productivity, fast conversion and altogether less hazardous chemical synthesis. Furthermore, it pushes towards designing of chemistry with a lower environmental and economic impact. In this study the synthesis of 2-pyridone moiety in a continuous flow coil-type microreactor system was examined. In order to optimize reaction conditions, flow rates of starting reagents were varied. The desirable 2-pyridone was obtained in satisfactory yield of circa 60% in less than 10 minutes. The structure and purity of synthetized 2-pyridone moiety were confirmed by melting point, FT-IR, 1 H NMR and UV-Vis spectra. The efficiency of the presented method for the synthesis of 2-pyridone based molecules has promising scaleup potential.