Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
2003-11-24
2004-12-07
Barts, Samuel (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S347000, C568S355000, C568S356000
Reexamination Certificate
active
06828464
ABSTRACT:
The present invention relates to a process for preparing 2-cyclopentenones by converting 2- or 3-hexene-1,6-dicarboxylic acids or their esters in the presence of heterogeneous catalysts which consist of alkali metal oxides on catalyst supports.
The synthesis of 2-cyclopentenones by converting substituted or unsubstituted 2- or 3-hexene-1,6-dicarboxylic acids or their esters over solid oxidic catalysts at from 150° C. to 450° C. is disclosed by EP-A 297 447. The catalysts used are solid oxidic catalysts of main groups I to V, transition groups I to VIII of the Periodic Table of the Elements or oxides of the rare earth metals or mixtures of the oxides mentioned. Particular preference is given to carrying out the reaction in the gas phase using a fluidized catalyst bed. According to the four examples of EP-A 297 447, the catalyst used is more preferably &ggr;-aluminum oxide or barium oxide-doped aluminum oxide.
The experiments in the four examples were conducted at 345° C./atmospheric pressure in the presence of steam, nitrogen as a carrier gas, and &ggr;-aluminum oxide or &ggr;-aluminum oxide/barium oxide fluidized bed catalysts, each for 6 hours. The highest yield when using &ggr;-aluminum oxide was 51% (selectivity 65%, example 1), and when using &ggr;-aluminum oxide/10% barium oxide 55% (selectivity 69%, example 4).
It is an object of the present invention to further improve the process for preparing cyclopentenones from 2- or 3-hexene-1,6-dicarboxylic acids or their esters, especially with regard to the cyclopentenone selectivity, by finding still better catalysts. A very high cyclopentenone yield should be combined with a high cyclopentenone selectivity, in order to have to recycle very little 2- or 3-hexene-1,6-dicarboxylic acids or their esters in the process. The catalysts should also have a very long on-stream time.
We have found that this object is achieved by a process for preparing 2-cyclopentenones of the general formula:
where R
1
to R
4
are each hydrogen atoms or are alkyl or alkenyl radicals having from 1 to 12 carbon atoms, cycloalkyl or cycloalkenyl radicals having from 5 to 7 carbon atoms, aralkylene or aryl radicals, by converting hexenedioic acids and/or their esters of the general formulae
where R
1
to R
4
are each as defined above and R
5
and R
6
are each hydrogen atoms or are alkyl radicals having from 1 to 12 carbon atoms, cycloalkyl radicals having 5 or 6 carbon atoms, aralkyl or aryl radicals, at temperatures of from 150 to 450° C., over solid, oxidic catalysts which, on an oxidic support material, comprise from 0.01 to 5% by weight, preferably from 0.1 to 3% by weight, more preferably from 0.3 to 2% by weight, of at least one alkali metal oxide. Percentages by weight are based in each case on the overall catalyst composed of active metal oxide and support material.
Useful alkali metal oxides are lithium oxide, sodium oxide, potassium oxide, rubidium oxide, and cesium oxide or mixtures thereof. Particular preference is given to sodium oxide and potassium oxide as the catalytically active composition.
Useful support materials are metal oxides of main groups II to V, transition groups I to VIII of the Periodic Table of the Elements, or oxides of the rare earth metals or mixtures thereof. Examples of such supports are magnesium oxide, calcium oxide, barium oxide, and also boron trioxide, aluminum oxide, silicon oxide, for example in the form of silica gel, kieselguhr or quartz, and also tin dioxide, bismuth oxide, copper oxide, zinc oxide, lanthanum oxide, titanium dioxide, zirconium dioxide, vanadium oxides, chromium oxides, molybdenum oxides, tungsten oxides, manganese oxides, iron oxides, cerium oxides, neodymium oxides, or mixtures of such oxides.
Preference is given to using aluminum oxide and/or silicon oxide as the support material.
The supported catalysts used in accordance with the invention can be prepared by processes known per se, for example by precipitating the catalytically active component from its salt solutions in the presence of the support material by adding an alkali metal hydroxide or carbonate solutions. The particular hydroxides, oxide hydrates, basic salts or carbonates are precipitated in this way.
The precipitates are subsequently dried and converted by calcining, generally at from 300 to 1300° C., preferably from 400 to 1200° C., to the corresponding oxides, mixed oxides and/or mixed-valency oxides.
In addition to the abovementioned precipitation catalysts which can be used as supported catalysts, also suitable are supported catalysts in which the catalytically active components have been applied to the support material in another way.
For example, the catalytically active components can be applied by impregnating with solutions or suspensions of the salts or oxides of the appropriate elements and drying.
The supported catalysts can also be prepared by mixing the support with an alkali metal salt and water, kneading and extruding the mixture and subsequently drying and calcining.
The catalytically active components can also be applied to the support by impregnating the support with solutions of salts which readily decompose thermally and heating the support treated in this way to temperatures of from 300 to 600° C., which thermally decomposes the adsorbent metal compounds.
Salts which readily decompose thermally are, for example, nitrates and complexes which readily decompose thermally, such as carbonyl or hydrido complexes of the catalytically active metals. Preference is given to carrying out the thermal decomposition in a protective gas atmosphere. Suitable protective gases are, for example, nitrogen, carbon dioxide, hydrogen or noble gases.
The catalytically active component can also be deposited on the support material by vapor deposition or flame spraying.
The reaction according to the invention can be illustrated, for example, for the conversion of dimethyl 3-hexene-1,6-di-carboxylate to 2-cyclopentenone by the following reaction equation:
Useful starting materials of the formulae II and III include 3-hexene-1,6-dicarboxylic acid or 2-hexene-1,6-dioic acid, each of which may optionally be substituted by the R
1
to R
4
radicals. The R
1
to R
4
radicals may be alkyl or alkenyl radicals having from 1 to 12 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, hexyl, nonyl, allyl, hexenyl or nonenyl radicals, cycloalkyl or cycloalkenyl radicals having from 5 to 7 carbon atoms, such as cyclohexyl, cyclopentyl, 2-cyclohexenyl or 2-cyclopentenyl radicals, aralkyl or aryl radicals, such as phenyl or benzyl radicals. The esters of the formulae II and III are aliphatic, cycloaliphatic, araliphatic or aromatic mono- or diesters of the dicarboxylic acids mentioned. Useful R
5
and R
6
radicals are, for example, methyl, ethyl, propyl, isopropyl, tert-butyl, hexyl, nonyl, dodecyl, cyclopentyl, cyclohexyl, phenyl or benzyl radicals.
The following starting materials, for example, can be used:
3-hexene-1,6-dioic acid, 2-hexene-1,6-dioic acid, 2-methyl-3-hexene-1,6-dioic acid, 2,5-dimethyl-3-hexene-1,6-dioic acid, 3,4-dimethyl-3-hexene-1,6-dioic acid, 2-allyl-3-hexene-1,6-dioic acid, 3-cyclohexyl-2-hexene-1,6-dioic acid, 3-(2-cyclopentyl)-3-hexene-1,6-dioic acid, 3-phenyl-3-hexene-1,6-dioic acid and 2-benzyl-3-hexene-1,6-dioic acid, dimethyl 3-hexene-1,6-dioate, dimethyl 2-hexene-1,6-dioate, monomethyl 3-hexene-1,6-dioate, diethyl 3-hexene-1,6-dioate, dibutyl 2-hexene-1,6-dioate, dicyclohexyl 3-hexene-1,6-dioate, dibenzyl 3-hexene-1,6-dioate, dimethyl 2-methyl-3-hexene-1,6-dioate, dimethyl 2,5-dimethyl-3-hexene-1,6-dioate, dimethyl 3,4-dimethyl-3-hexene-1,6-dioate, dimethyl 2-allyl-3-hexene-1,6-dioate, diethyl 3-cyclohexyl-2-hexene-1,6-dioate, dimethyl 3-(2-cyclopentenyl)-3-hexene-1,6-dioate, diethyl 3-phenyl-3-hexene-1,6-dioate or dimethyl 2-benzyl-3-hexene-1,6-dioate. The conversion of the esters is of particular industrial interest.
Although it is possible to carry out the reaction according to the invention without addition of water, the addition of water achieves a remarkable increase of
Fischer Rolf-Hartmuth
Haunert Andrea
Huber-Dirr Sylvia
Liang Shelue
Barts Samuel
BASF - Aktiengesellschaft
Keil & Weinkauf
Witherspoon Sikarl A.
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