Electrosynthesis of p-hydroxybenzaldehydefrom sodium p-hydroxymandelate

The electrosynthesis of p-hydroxybenzaldehyde (PHB) from sodium p-hydroxymandelate (SPHM) was investigated and good synthesis conditions were obtained. The electrochemical reactor was a divided filter-press with carbon felt electrodes (anode and cathode). Two different anolytes were used depending on the membrane employed. Thus, a 0.6m SPHM 2.7m NaOH solution was used in conjunction with a cationic Nafion® 117 membrane while a 0.6m SPHM in 1.8m NaOH solution was employed with an anionic Ionac® MA-3475 membrane. The electrolysis was carried out at a constant current density of 100mAcm–2. A material yield of approximately 90% was obtained at an energy cost of 1.4–1.5kWhkg–1 PHB and a production of 49kg PHBm–2 day–1.