Hoechst Aktiengesellschaft

Helmut Meidert

Werner H Muller

Wilfried Pressler

Heinz Litterer

Hansjorg Hey

Wilhelm Riemenschneider

Hans Krekeler

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.

Process for the isolation of crystalline 1,3-cylohexanedione

8-Oxo-5,6,7,8-tetrahydro-2-quinolone is a novel compound which is prepared by hydrolyzing the hydrochloride of the corresponding 8-chloro compound or the hydrobromide of the corresponding 8-bromo compound to give the corresponding 8-hydroxy compound, and dehydrogenating the latter one.

8-Oxo-5,6,7,8-tetrahydro-2-quinolone and process for the preparation

8-Chloro-5,6,7,8-tetrahydro-2-quinolone and 8-bromo-5,6,7,8-tetrahydro-2-quinolone, the hydrochloride or hydrobromide thereof and their manufacture by reacting 3,4,5,6,7,8-hexahydro-2-quinolone with chlorine or bromine in an inert solvent at 10.degree. to 50.degree. C. with heating of the reaction mixture to 60.degree. to 80.degree. C. after the halogen addition.

8-Chloro-5,6,7,8-tetrahydro-2-quinolone and

Cyclohexane-1,3-diones of the formula ##STR1## having up to 24 carbon atoms are prepared in admixture with 6-alkyl-3,4-dihydro-2-pyranones of the formula ##STR2## having up to 24 carbon atoms, in which formulae the radicals R and R' may be identical or different and represent each a hydrogen atom, an alkyl, a cycloalkyl or an aryl group each having up to 12 carbon atoms and the two radicals R' together optionally represent a --(CH.sub.2).sub.3 -group, by passing 4-oxocarboxylic acids of the formula ##STR3## having up to 24 carbon atoms and in which R and R' have the above meaning at a temperature of from 250.degree. to 500.degree. C in the gaseous phase over a dehydration catalyst and the pyranones are converted into cyclohexane-1,3-diones by passing them in the gaseous phase over a dehydration catalyst at a temperature of from 250.degree. to 500.degree. C.

Process for the manufacture of cyclohexane-1,3-diones and

A process for the preparation of a mixture of carbon tetrachloride and phosgene in the absence of a catalyst from

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Frankfurt am Main, Germany

Helmut Meidert