Process for the preparation of isobenzofurandiones
AssigneeBayer Aktiengesellschaft
InventorsJosef Kasbauer, Helmut Fiege
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Abstract
Isobenzofurandiones are obtained in particularly advantageous manner by the dehydrogenation of tetrahydroisobenzofurandiones in the presence of catalysts at elevated temperature by a process in which distilled tetrahydro-isobenzofurandiones are heated to temperatures of between 120.degree. and 300.degree. C. in the presence of supported palladium and/or platinum catalysts and in the presence of maleic acid derivatives in a trickle-phase or liquid-phase procedure, the temperature in the liquid-phase procedure being increased at a rate of 0.6.degree. to 3.degree. C. per minute above 80.degree. to 110.degree. C.
Claims8
Process for the preparation of an isobenzofurandione by the dehydrogenation of a tetrahydroisobenzofurandione in the presence of a catalyst at elevated temperature, characterized in that a solution of a distilled tetrahydroisobenzofurandione and a maleic acid derivative selected from the group consisting of maleic anhydride, maleimides, maleamic acid and alkyl maleates is contacted with a supported palladium catalyst, a supported platinum catalyst or both in a trickle-phase process at a temperature of 120.degree. to 300.degree. C.
Process for the preparation of an isobenzofurandione by the dehydrogenation of a tetrahydroisobenzofurandione in the presence of a catalyst at elevated temperature, characterized in that a distilled tetrahydroisobenzofurandione is heated to temperatures of between 120.degree. and 300.degree. C. in the presence of a supported palladium catalyst, a supported platinum catalyst or both, and in the presence of a maleic acid derivative selected from the group consisting of maleic anhydride, maleimides, maleamic acid and alkyl maleates in a liquid-phase process, wherein, when the temperature is being increased to reaction temperature, it is increased at a rate of from 1.0.degree. to 3.degree. C. per minute as the temperature passes through the range of from above 80.degree. to 110.degree. C.
Dependencies are inferred from the claim text.