Ivan Halasz group | Milling and monitoring

July 19, 2023.

While studying a series of imine condensations in searching for the Hammett correlation in the solid state, the one reaction with 4-nitrobenzaldehyde and 4-nitroaniline would not move, not by a single iota. We attempted catalysis by acids and found, by experiment and modelling, that carboxylic acids are ideally suited to assist in proton transfer. Dedicated to Prof. Branko Kaitner, on the occasion of his 80th birthday.

full paper

We now describe and explain the catalysis, in particular by acids, in the mechanochemical C=N bond formation. We were searching for the intermediates aiming to find the initial intermediate, the hemiaminal resulting from addition of the amine to the aldehyde, but we could not observe it directly and have inferred its formation from the intermediate formation of the aminal.