Journal of Molecular Catalysis A-Chemical, Vol.341, No.1-2, 22-27, 2011
Nanocrystalline MgO catalysts for the Henry reaction of benzaldehyde and nitromethane
Nanocrystalline MgO particles of about 3 nm were examined as catalysts for the Henry reaction between benzaldehyde and nitromethane at 273 K. The surface area of nanocrystalline MgO was greater than 600 m(2) g(-1) except after thermal treatment in N(2) at 823 K, which reduced the surface area to 359 m(2) g(-1). The areal rate of the Henry reaction over nanocrystalline MgO at 273 K was 0.015 +/- 0.002 mu mol m(-2) s(-1) and was independent of pretreatment temperature over the range of 523-823 K. Addition of (S)-BINOL to nanocrystalline MgO has been reported previously to favor the production of one enantiomer of the Henry reaction. In the current work, negligible enantiomeric excess was observed on (S)-BINOL-modified nanocrystalline MgO catalysts, regardless of the source of nanocrystalline MgO. the MgO activation temperature, the reaction temperature, the sequence of reactant addition or the loading of (S)-BINOL. Adsorption of L-proline onto nanocrystalline MgO catalyst induced a small enantiomeric excess in the Henry reaction products, but the catalytic activity of the catalyst was low. (C) 2011 Elsevier B.V. All rights reserved.