Solvent effect on the reversibility of base catalyzed Henry reactions : Triton B catalyzed nitro aldol reactions in alcohol

The amine catalyzed nitro aldol reactions between nitromethane and aldehydes are found to be reversible in an alcohol solvent on the basis of the reaction monitoring by 1H NMR spectroscopy. The reaction in alcohols is particularly rapid to complete the equilibrium in a short period of time at room temperature, producing nitro aldol product in high yields. Triton B is especially effective as catalyst in the nitro aldol reactions of nitromethane in methanol. Only a small catalytic loading of triton B as small as 1 mol% is enough to finish the reaction. Aromatic, aliphatic, and {alpha},{beta}-unsaturated aldehydes as well as aldehyde hydrates and aqueous aldehydes are successfully employed.