4-Hydroxymandelic acid
# 4-Hydroxymandelic acid

4-Hydroxymandelic acid is a chemical compound used to synthesize atenolol. The compound typically occurs as a monohydrate.

## Synthesis and occurrence

It is produced from 4-hydroxypyruvic acid by the action of the enzyme (S)-p-hydroxymandelate synthase:

    $HOC_6H_4CH_2C(O)CO_2H$ + $O_2$ → $HOC_6H_4CH(OH)CO_2H$ + CO2

4-Hydroxymandelic acid can be synthesized by the condensation reaction of phenol and glyoxylic acid:

    $HOC_6H_5$ + $CHOCO_2H$ → $HOC_6H_4CH(OH)CO_2H$
