Non-Green Elements Takes long time as the reaction was inefficient since it needed 20 hours to achieve a complete reaction. The atom economy calculated for this reaction is only 56.31%, excluding water. Atom economy shows the amount of reactant transformed into the desired product. Thus, 56.31% is not that great. The reaction seems a one-pot reaction; So, contaminants from previous chemicals and recrystallization may need a purified with one or two more step which generates significant amounts of waste.