Abstract 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 2 ) 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° to 500° 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° to 500° C.
A process for the manufacture of cyclohexane- 1,3-diones of the formula I ##STR8## having up to 24 carbon atoms in admixture with 6-alkyl-3,4-dihydro-2-pyranones of the formula II ##STR9## having up to 24 carbon atoms, in which formulae the radicals R and R' may be identical or different and each represent 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 2 ) 3 -group, which comprises passing 4-oxocarboxylic acids of the formula III ##STR10## having up to 24 carbon atoms and in which R and R' have the above meaning at a temperature of from 250° to 500° C. in the gaseous phase over a dehydration catalyst.
Claim 2
Dependent Claim
125 words
A process for the manufacture of cyclohexane- 1,3-diones of the formula I ##STR8## having up to 24 carbon atoms in admixture with 6-alkyl-3,4-dihydro-2-pyranones of the formula II ##STR9## having up to 24 carbon atoms, in which formulae the radicals R and R' may be identical or different and each represent 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 2 ) 3 -group, which comprises passing 4-oxocarboxylic acids of the formula III ##STR10## having up to 24 carbon atoms and in which R and R' have the above meaning at a temperature of from 250° to 500° C. in the gaseous phase over a dehydration catalyst.
Claim 3
Dependent Claim
20 words
The process of claim 1, wherein the catalyst is phosphoric acid or polyphosphoric acid supported on an inert carrier material.
Claim 4
Dependent Claim
37 words
The process of claim 1, wherein the catalyst is γ-aluminum oxide, titanium dioxide in the anatase modification, thorium oxide, tungsten oxide, silicon dioxide, zirconium dioxide, a mixture thereof or a mixed oxide thereof, or an aluminum silicate.