4-dimethylaminocinnamaldehyde as a photometric reagent for primary aromatic amines

The interaction of primary aromatic amines (PAAs) with 4-dimethylaminocinnamaldehyde (DMACA) is studied in various media by UV, IR, and H-1 NMR spectroscopy. The optimum conditions for these reactions have been found, and the reasons for better analytical effects in the condensation reaction of PAAs with this reagent have been revealed. The physicochemical properties of the analytical form are studied using the aniline-DMACA model system as an example. A correlation has been found between the pH(opt) of the reactions under study and the pK(a) values of arylamines.