科研之友
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摘要
We report a theoretical study on non-conventional structures of 1:1 complexes between carbon dioxide and carbonyl compounds. These structures have never been reported before but are relevant for understanding the solubility of carbonyl compounds in supercritical CO2. The work is based on the results of ab initio calculations at the MP2 and CCSD(T) levels using aug-cc-pVDZ and aug-cc-pVTZ basis sets. Investigated systems include aldehydes, ketones and esters, together with some fluorinated derivatives. The results are interpreted in terms of natural bond orbital analyses. Harmonic vibrational frequency calculations have also been done in order to compare them with available experimental data. We show for the first time that complexes where CO2 behaves globally as a Lewis base are stable in the case of ketones and esters, but not in the case of aldehydes, and their stability is similar to that of traditional complexes in which CO2 behaves as a Lewis acid. This finding considerably modifies the concept of CO2-philicity and may have important ramifications in the development of green reactions in supercritical CO2.
- 出版日期2012-10-8
