Theoretical study on the mechanism of reaction between 3-hydroxy-3-methyl-2-butanone and malononitrile catalyzed by magnesium ethoxide

The mechanism of reaction between 3-hydroxy-3-methyl-2-butanone and malononitrile for the synthesis of 2-dicyanomethylene-4,5,5-trimethyl-2,5-dihydrofuran-3-carbonitrile catalyzed by magnesium ethoxide was investigated by density functional theory (DFT). The geometries and the frequencies of reactants, intermediates, transition states, and products were calculated at the B3LYP/6-31G(d) level, The vibration analysis and the IRC analysis demonstrated the authenticity of transition states, and the reaction processes were confirmed by the changes of charge density at bond-forming critical point. The results indicated that magnesium ethoxide is an effective catalyst in the synthesis of 2-dicyanomethylene-4,5,5-trimethyl-2,5-dihydrofuran-3-carbonitrile from malononitrile and 3-hydroxy-3-methyl-2-butanone. The activation energy of reaction with magnesium ethoxide decreased by 102.37 kJ mol(-1) compared with that of the reaction without it. The mechanism of reaction with catalyst magnesium ethoxide differs from that of reaction without it. (c) 2008 Wiley Periodicals, Inc. Int J Chem Kinet 41:227-235, 2009