| 摘要 |
A process is disclosed for making 1,3-cyclic diones by vapor-phase cyclization of delta-keto carboxylic acid esters over a carbon catalyst bed. The delta-keto ester is conveyed through the catalyst bed by a carrier gas characterized by being liquid at 25 DEG C. and having a sufficiently high boiling point that the carrier gas is easily condensable under ambient conditions. The delta-keto ester is highly soluble in the liquid carrier, while the cyclic dione product of the ester has very low solubility in the liquid carrier. Use of the described carrier in vapor-phase cyclization of delta-keto esters allows efficient separation of cyclic dione product and unreacted starting material from the carrier after the cyclization reaction.
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