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 m2 g−1 except after thermal treatment in N2 at 823 K, which reduced the surface area to 359 m2 g−1. The areal rate of the Henry reaction over nanocrystalline MgO at 273 K was 0.015 ± 0.002 μmol 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.

Modification of nanocrystalline MgO with BINOL does not produce an enantiomeric excess of products from the base-catalyzed Henry reaction of benzaldehyde and nitromethane.Figure optionsDownload high-quality image (120 K)Download as PowerPoint slideHighlights
► Nano-MgO is an effective catalyst for reaction of benzaldehyde and nitromethane.
► The areal rate on MgO is not affected by thermal treatment between 523 and 823 K.
► No enantiomeric excess is observed in products formed over S-BINOL-modified MgO.