Behavior of Some P-Hydroxybenzaldehyde Derivatives toward Oxidizing Agents

Benzaldehyde1 and its alkyl, alkoxy and halogen substitution products are readily oxidized to the corresponding acids. Contact with air often brings about the change.2 Biicking,3 and Fittig and Remsen4 found that p-hydroxybenzaldehyde and protocatechuic aldehyde, respectively, are not readily oxidized by potassium permanganate solution. Tiemann5 could not oxidize vanillin, the 3-methyl ether of protocatechuic aldehyde, into vanillin acid by the usual methods, and Brady and Dunn6 failed to oxidize 5- bromovanillin with acetic acid solution of chromic acid and also by alkaline solution of potassium permanganate. The behavior of many vanillin substitution products7 toward the last-named reagent is now being studied. If the hydroxyl group in position 4 is exposed almost all the starting material is recovered. When the alkyl derivatives are used the corresponding acids are obtained. Results thus far indicate that the weight of the alkyl group may determine the yield of product. When a heavy alkyl is present the yield is low. 1 Wohler and Liebig, Ann., 3,250 (1832). 2 Bornemann, Ber., 17, 1466 (1884). 3 Bucking, Ber., 9,529 (1876). 4 Fittig and Remsen, Ann., 159, 150 (1871). 5 Tiemann, Ber., 9, 415 (1876). 6 Brady and Dunn, J. Chem. Soc., 107, 1859 (1915). 7 Raiford and Wells, J. Am. Chem. Soc., 57, 2500 (1935)