Carbon dioxide
Chemical reactions

CO is a potent electrophile having an electrophilic reactivity that is comparable to benzaldehyde or strongly electrophilic α,β-unsaturated carbonyl compounds. However, unlike electrophiles of similar reactivity, the reactions of nucleophiles with CO are thermodynamically less favored and are often found to be highly reversible. The reversible reaction of carbon dioxide with amines to make carbamates is used in CO scrubbers and has been suggested as a possible starting point for carbon capture and storage by amine gas treating.Only very strong nucleophiles, like the carbanions provided by Grignard reagents and organolithium compounds react with CO to give carboxylates:

In metal carbon dioxide complexes, CO serves as a ligand, which can facilitate the conversion of CO to other chemicals.

The reduction of CO to CO is ordinarily a difficult and slow reaction:

The redox potential for this reaction near pH 7 is about −0.53 V versus the standard hydrogen electrode. The nickel-containing enzyme carbon monoxide dehydrogenase catalyses this process.

Photoautotrophs (i.e. plants and cyanobacteria) use the energy contained in sunlight to photosynthesize simple sugars from CO absorbed from the air and water:
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