PRODUCTION OF P-HYDROXYBENZALDEHYDE

PURPOSE:To obtain, with industrial advantage, the title compound by specifying the oxidation, reactor, the oxygen concentration in the gas phase, the oxygen partial pressure, the agitation power and the depth of the reaction mixture, when p-cresol is oxidized in a solvent in the presence of a cobalt compound and a base. CONSTITUTION:When the title compound is prepared by oxidation of p-cresol or a mixture thereof with oxygen or a gas containing the same in a solvent in the presence of a cobalt compound and a base, an aeration agitation type reactor in which the gas in the reactor space is sucked by rotation of the agitation blades through the agitation hollow shaft into the bottom of the reactor or a reactor in which the reaction mixture at the bottom is recycled with a pump is used for the oxidation and oxygen or a gas containing the same is introduced so that the oxygen concentration in the gas phase becomes 0.1-12% to effect the oxidation at an average oxygen partial pressure of 0.1-2atms, agitation power of 1.5Kw/m , the mixture depth of 0.2-10m. Thus, the subject compound is obtained easily through industrial operation at a high reaction rate in high yield.