Chemical Education Today
Corrections The article “Chemical Reactions in Supercritical Carbon Dioxide” (Wai, C. M.; Hunt, F.; Ji, M.; Chen, X. J. Chem. Educ. 1998, 75, 1641–1645) should be corrected as follows: On page 1641 under the section Hydrogenation and Hydroformylation, the first paragraph should appear as shown at the right with corrections in boldface. The work by Jessop et al. was mistakenly cited as by Leitner et al. in the article. We apologize for the mistake. C. M. Wai Department of Chemistry University of Idaho, Moscow, ID 83844
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Hydrogenation and Hydroformylation High concentrations of CO2 in the supercritical fluid phase can be advantageous for chemical reactions that incorporate CO2. For example, in conventional synthesis, hydrogenation of CO2 to formic acid is rendered thermodynamically favorable by the addition of a base in an organic solvent. This reaction is highly efficient in sc-CO2 (Scheme I). The hydrogenation of CO2 to formic acid using an organic rhodium catalyst in dimethyl sulphoxide in a pressurized system was investigated by Graf and Leitner (11). Efficient production of formic acid in a supercritical mixture of CO 2 and H2, containing a trimethylphosphine complex of RuII as a catalyst precursor, was reported by Jessop et al. (12). The use of a sc-CO2 phase, in which hydrogen can be dissolved with a much higher concentration, leads to a very high initial rate of reaction—up to 1,400 moles of formic acid per mole of catalyst per hour. The rate of the same reaction under identical conditions in liquid organic solvents is lower by an order of magnitude (12).
Journal of Chemical Education • Vol. 76 No. 2 February 1999 • JChemEd.chem.wisc.edu
