4-Hydroxybenzaldehyde

4Hydroxy&shy;benzaldehyde (parahydroxy&shy;benzaldehyde) is an organic compound with the formula C6H4OH(CHO). Along with 2-hydroxybenzaldehyde and 3-hydroxybenzaldehyde, it is one of the three isomers of hydroxybenzaldehyde.

Synthesis, reactions, uses
4-Hydroxybenzaldehyde is prepared by reaction of phenol with chloroform, which gives isomeric hydroxybenzal chlorides. Hydrolysis of the C-Cl bonds gives the aldehyde.

4-Hydroxybenzaldehyde is a precursor to 4-hydroxyphenylglycine, a precursor to penicillins. In the Dakin oxidation, 4-hydroxybenzaldehyde reacts with hydrogen peroxide in base to form hydroquinone.

Metabolism and occurrence
p-Hydroxybenzaldehyde dehydrogenase is an enzyme found in carrots (Daucus carota).

4-Hydroxybenzaldehyde is found in the orchids Gastrodia elata, Galeola faberi, and the Vanilla orchids.