Efficient chemical fixation and defixation cycle of carbon dioxide under ambient conditions

Abstract

Chemical fixation of CO2 as a C1 feedstock for producing value-added products is an important post-combustion technology reducing the CO2 emission. As it is an irreversible process, not considered for the CO2 capture and release. Overall, these chemical transformations also do not help to mitigate global warming, as the energy consumed in different forms is much higher than the amount of CO2 fixed by chemical reactions. Here we describe the development of re-generable chemical fixation of CO2 by spiroaziridine oxindole, where CO2 is captured (chemical fixation) under catalyst-free condition at room temperature both in aqueous and non-aqueous medium even directly from the slow stream of flue gas producing regioselectively spirooxazolidinyl oxindoles, a potential drug. The CO2-adduct is reversed back to the spiroaziridine releasing CO2 under mild conditions. Further both the fixation-defixation of CO2 can be repeated under near ambient conditions for several cycles in a single loop using a recyclable reagent.