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

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.