The Fixation of Carbon Dioxide and Nitrogen

The Fixation of Carbon Dioxide and Nitrogen.—As reduced carbon compounds are convenient fuels, the possibility of achieving the reductive fixation of COa in vitro is appealing, if remote. There are very few data on photochemical reactions involving carbon dioxide, for it has no low-lying excited states and has not historically been of much interest to the photochemist. However, what appears to be the first example of photofixation of COa in a non-biological system has been briefly reported.18 Photoirradiation (with a high-pressure mercury lamp) of phenanthrene in the presence of an amine and C02 in a polar solvent (MeaSO or HCONMea) yielded 9,10-dihydrophenanthrene-9-carboxylic acid, in unspecified quantum yield. The mechanism appears to involve formation of COaT by electron transfer from the photoexcited amine, followed by attack of COaT on position 9 of phenanthrene. Similar reductive carboxylation of anthracene, pyrene, naphthalene, and biphenyl was observed. 

Chapman6 has pointed out that bivalent carbon can fix both COa and Na according to reactions (2) and (3). 

The fixation of molecular nitrogen has been discussed by Fischler and Koerner von Gustorf,22 who point out that Mn+,N=N has a CTTL transition this 

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