A comparison of green chemistry metrics for two methods of bromination and nitration of bis-pyrazolo[3,4-b;4',3'-e]pyridines

Abstract

Green chemistry metrics (E-factor, atom economy, reaction mass efficiency) and the EcoScale have been compared for conventional heating and microwave assisted bromination and nitration of bis-pyrazolo[3,4-b;4 ' ,3 '-e]pyridines. The major advantages in microwave-assisted reactions in relation to traditional evaluation of the process have encompassed higher yields, shorter reaction time and higher selectivity. The microwave-assisted reactions have shown better green chemistry parameters and EcoScale ranks than those in conventionally heated reactions. Mass reaction efficiency values have been critical for considering 'green' the reactions conducted under traditional conditions. Additional advantages of using microwaves, not considered in calculated parameters, include easier purification of the reaction mixture and isolation of the product. 2011 · Copyright © by Walter de Gruyter.