Comparison of nitroaldol reaction mechanisms using accurate ab initio calculations.
In the nitroaldol reaction, condensation between a nitroalkane and an aldehyde yields a nitroalcohol that can undergo dehydration to yield a nitroalkene. Amine-functionalized, MCM-41-type mesoporous silica nanosphere (MSN) materials have been shown to selectively catalyze this reaction. Gas-phase reaction paths for the several competing mechanisms for the nitroaldol reaction have been mapped out using second-order perturbation theory (MP2). Improved relative energies were determined using singles and doubles coupled cluster theory with perturbative triples, CCSD(T). The mechanism in the absence of a catalyst was used to provide a baseline against which to assess the impact of the catalyst on both the mechanism and the related energetics. Catalyzed mechanisms can either pass through a nitroalcohol intermediate as in the classical mechanism or an imine intermediate.
Zorn
Deborah
D
Ames Laboratory and Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA.
Lin
Victor S-Y
VS
Pruski
Marek
M
Gordon
Mark S
MS