The Zincke reaction poses a difficulty when attempting to purify the crude mixtures and isolate reaction products in analytically pure form. This paper introduces the successful method of using the centrifugal partition chromatography (CPC) to isolate pyridinium salts garnered by this reaction returning good yields and high degrees of purity. Efficient purifications were obtained by using (n‐BuOH/MeOH/H2O) biphasic solvent systems. The CPC confirmed its suitability for isolating compounds prone to decompose during purification on solid stationary phases. It has also proved to be an efficient method for valorizing incomplete Zincke reactions.
In the presence of amines, the degradation of glutaconaldehyde
in acidic medium can be prevented. By exploitation of this behavior,
primary amines are transformed into their corresponding pyridinium
salts, including those substrates that remain unreactive toward the
Zincke salt, which is the reagent typically used to perform this transformation.
The use of glutaconaldehyde also allows control of the nature of the
counterion of the pyridinium with no need for additional salt metathesis
reaction.
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