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

Chemical fixation of CO as a C1 feedstock for producing value-added products is an important post-combustion technology reducing the CO emission. As it is an irreversible process, not considered for the CO 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 CO fixed by chemical reactions. Here we describe the development of re-generable chemical fixation of CO by spiroaziridine oxindole, where CO 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 CO-adduct is reversed back to the spiroaziridine releasing CO under mild conditions. Further both the fixation-defixation of CO can be repeated under near ambient conditions for several cycles in a single loop using a recyclable reagent.