| 摘要 |
The invention relates to a process for the isolation of crystalline 1,3-cyclohexanedione from the crude product formed in catalytic gas-phase cyclisation of 5-oxohexanoic acid. This is done by adding to the crude product, before or directly after condensation, an auxiliary component comprising at least one compound from the group comprising cyclic hydrocarbons, chlorinated aliphatic hydrocarbons and monoethers, then distilling the mixture comprising crude product and auxiliary component under atmospheric or reduced pressure until the water of reaction has been removed and the residual content of auxiliary component in the remaining concentrate has reached a certain value and filtering off the crystalline 1,3-cyclohexanedione precipitated after this treatment. It is also possible to distil off the auxiliary component added virtually completely from the 1,3-cyclohexanedione. In this case, one, either the same or a different, compound or compound mixture mentioned as auxiliary components must then be added again to the remaining concentrate which is interspersed with crystals, so that the 1,3-cyclohexanedione separates out as completely as possible as crystals and a crystalline paste which can be filtered is formed.
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