| 摘要 |
PURPOSE:To crystallize and separate the subject compound in the form of sodium salt by oxidizing p-cresols in methanol, adding methanol to the resultant reaction mixture, filtering the obtained mixture, then adding water thereto, distilling away the methanol and cooling the resultant mixture. CONSTITUTION:p-Cresols are oxidized with oxygen or an oxygen-containing gas in the presence of a catalyst containing sodium hydroxide and a cobalt compound in methanol. Methanol is further added to the resultant reaction mixture and formed tar, etc., are filtered off. Water is then added to heat the resultant mixture at 50-100 deg.C temperature to distill away the methanol and cool the solution temperature to -20 to +50 deg.C, preferably 0-20 deg.C, crystallize and separate p-hydroxybenzaldehyde in the form of sodium salt. The separated crystals are subsequently dissolved in water and active carbon, etc., as necessary, are added to carry out filtration. The resultant filtrate is then neutralized with a mineral acid to crystallize and separate the objective compound. |
