| 摘要 |
PURPOSE:To obtain the subject compounds useful as an intermediate for synthesis of a pyrazole derivative used as an agricultural germicide in a high yield by reacting an alkyl acetoacetate with ethyl orthoformate while continuously adding acetic anhydride catalyst thereto and distilling off generated low boiling substances. CONSTITUTION:In a reaction between an alkyl acetoacetate and ethyl orthoformate using acetic anhydride as a catalyst, the reaction is carried out while continuously adding acetic anhydride at 9-10g/min. and distilling off generated low boiling substances containing acetic acid. By addition of acetic anhydride within the above-mentioned range, a bumping due to a vigorous reaction can be prevented and thermal decomposition of the objective substance can be lowered. In addition, the decomposition can be inhibited by distilling off acetic acid. Based on 1mol alkyl acetoacetate, 1.2-1.5mol ethyl orthoformate and 3.0-4.0mol acetic anhydride are preferably used. |
