| 摘要 |
<p>The invention provides a process for the isolation of crystalline 1,3-cyclohexanedione from the crude product formed in the catalytic gaseous phase cyclization of 5-oxohexanoic acid. Before or directly after condensation an auxiliary component consisting of at least one compound selected from the group consisting of cyclic hydrocarbons, chlorinated aliphatic hydrocarbons and monoethers is added to the crude product, subsequently the mixture of crude product and auxiliary component is distilled under normal or reduced pressure until the reaction water is removed and the residual content of auxiliary component in the remaining concentrate has attained a defined value, and the precipitated crystalline 1,3-cyclohexanedione is filtered off. Alternatively, the auxiliary component added may be distilled off substantially completely. In this case, either the same or another of the compounds or compound mixtures indicated as auxiliary component must be added subsequently to the remaining concentrate interspersed with crystals in order to obtain a substantially complete precipitation of the 1,3-cyclohexanedione in the form of crystals and formation of a filterable crystal pulp. Alternatively, the crude product may be heated after condensation and the crude crystallized product obtained optionally after cooling be mixed with the auxiliary component. The further work-up is as described above.</p> |
