Addition of cyanide ions to aromatic aldehydes: a competition method for the determination of equilibrium constants of nucleophilic addition reactions

Abstract

The equilibrium concentration of the cyanide Meisenheimer adduct of 1,3,5-trinitrobenzene, formed from potassium cyanide–18-crown-6 and trinitrobenzene, in DMSO solution, is reduced in the presence of an aromatic aldehyde, with an accompanying decrease in the absorbance of the solution due to the intensely coloured Meisenheimer adduct. Equilibrium constants have accordingly been determined for the formation of the cyanide Meisenheimer adduct of trinitrobenzene and for the formation of members of a series of substituted benzaldehyde cyanohydrin anions in dimethyl sulphoxide solution.