Polarographic reduction of aldehydes and ketones. Part 7.—Behaviour of cinnamaldehyde at higher pH-values
Abstract
When the rate of protonation of the radical anion formed in the uptake of the first electron decreases with increasing pH, the two-electron reduction wave of cinnamaldehyde decreases to a one-electron wave, followed at –1.5 V by another one-electron wave which corresponds to the radical anion reduction. With increasing alkali metal concentration a new wave iM is formed between these two waves which corresponds to the reduction of a product of a reaction of metal cations with cinnamaldehyde radical anion. In this interaction the reactivity increases in the sequence : Li+, Na+ < K+ < Rb+ < Cs+≪N(CH3)4≪N(C2H5)4. The wave of 3-phenylpropionaldehyde formed in the first two-electron uptake is observed at –1.7 V and its height is limited by the rate of dehydration.
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