24dihydroxybenzaldehyde

2,4-dihydroxybenzaldehyde, also known as protocatechualdehyde, is an aromatic organic compound with the molecular formula C7H6O3. The IUPAC name for the compound is 2,4-dihydroxybenzaldehyde, and it may also be referred to by the systematic name 1,3-dihydroxybenzaldehyde when the formyl group is considered at position 1. It is a white to pale yellow solid that is soluble in most organic solvents such as ethanol, acetone, and benzene, and it is slightly soluble in water. The compound is obtained typically by the selective oxidation of 2,4-dihydroxybenzyl alcohol or by the Bell–Rholin method from 3,4-dihydroxybenzaldehyde through a series of protection and deprotection steps. 2,4-dihydroxybenzaldehyde can also be prepared from 4-hydroxybenzenesulfonic acid using a Suzuki coupling followed by desulfonation and oxidation. In chromatography, it elutes as a moderate non-polar substance and can be characterized by its UV absorbance maximum near 240 nm and distinctive NMR signals for the aldehyde proton around 9.8 ppm.

The molecule is of interest in natural product chemistry and serves as a key intermediate in the synthesis of flavonoids and related phenolic compounds. It is also employed as a building block in the preparation of dyes, flavoring agents, and pharmaceutical intermediates. While not extensively used in large commercial processes, laboratory studies have shown that 2,4-dihydroxybenzaldehyde can function as a phenolic antioxidant and may exhibit moderate antimicrobial activity. Safety data indicate that it should be handled with caution, as the aldehyde functionality can be reactive; standard laboratory protective measures and avoidance of inhalation are advised.