It is known that benzaldehyde (17) and its alkyl, alkoxy and halogen substitution products are easily oxidized to the corresponding acids. In many cases contact with air brings about the change (4). The presence of hydroxyl as a substituent often makes the aldehyde less reactive toward oxidizing agents. For example, Bücking (3) and Fitting and Remsen (5) reported that p-hydroxybenzaldehyde and protocatechuic aldehyde, respectively, are not readily oxidized by potassium permanganate solution, but require fusion with caustic potash to give the related acids. Tiemann (13) found that when vanillin, the 3-methyl ether of protocateuchuic aldehyde, is treated with oxidizing agents hardly any change takes place or else complete decomposition occurs, depending on conditions, while Brady and Dunn (2) failed to oxidize 5-bromovanillin with acetic acid solution of chromic acid and also by alkaline solution of potassium permanganate.
Proceedings of the Iowa Academy of Science
©1940 Iowa Academy of Science, Inc.
Webster, Victor S. and Raiford, L. Chas.
"Oxidation of 4-Acyloxy Derivatives of Cinnamic Acid,"
Proceedings of the Iowa Academy of Science, 47(1), 249-255.
Available at: https://scholarworks.uni.edu/pias/vol47/iss1/47