| 摘要 |
<p>A process for preparing piperonal, characterized by comprising the three successive steps: (A) the addition step of reacting 1,2-methylenedioxybenzene with glyoxylic acid in the presence of a strong acid to form 3,4-methylenedioxymandelic acid, (B) the extraction step of adding an organic solvent to the reaction fluid and then neutralizing the resulting fluid with a base to thereby extract 3,4-methylenedioxymandelic acid into the organic solvent and separate the fluid into an organic solvent layer and an aqueous layer, and (C) the oxidation step of removing the aqueous layer, concentrating the organic solvent layer, adding nitric acid to the concentrate, and then making the 3,4-methylenedioxymandelic acid react with the nitric acid to form piperonal.</p> |
