Method for oxidizing a 1,1,-bis-(3,4-dimethylphenyl)-alkane to 3,3′,4,4′-benzophenone tetracarboxylic acid
AssigneeEvonik Fibres GmbH
InventorHarald Rögl
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Abstract
In a method for oxidizing 1,1-bis-(3,4-dimethylphenyl)-alkane with nitric acid in a pressure vessel to produce 3,3′,4,4′-benzophenone tetracarboxylic acid with concurrent formation of nitric oxide, passing nitric oxide from the pressure vessel into an absorption vessel and reacting nitric oxide in the absorption vessel with molecular oxygen and water to produce an aqueous nitric acid solution prevents discharge of nitric oxide, avoids the risk of oxygen inhibiting the nitric acid oxidation and reduces nitric acid consumption when the nitric acid from the absorption vessel is used for oxidizing the 1,1-bis-(3,4-dimethylphenyl)-alkane.
Claims20
A method for oxidizing a 1,1-bis-(3,4-dimethylphenyl)-alkane to 3,3′,4,4′-benzophenone tetracarboxylic acid, comprising:
- reacting the 1,1-bis-(3,4-dimethylphenyl)-alkane or a partial oxidation product thereof with nitric acid in a pressure vessel at a temperature of from 120 to 220° C.;
- providing 3,3′,4,4′-benzophenone tetracarboxylic acid with formation of nitric oxide;
- passing the nitric oxide from the pressure vessel into an absorption vessel;
- and
- reacting the nitric oxide in the absorption vessel with molecular oxygen and water to produce an aqueous nitric acid solution.
A method for oxidizing a 1,1-bis-(3,4-dimethylphenyl)-alkane to 3,3′,4,4′-benzophenone tetracarboxylic acid, comprising the steps:
- a) reacting the 1,1-bis-(3,4-dimethylphenyl)-alkane with a first aqueous nitric acid composition at a temperature of from 90 to 115° C. to provide a reaction mixture with two liquid phases, an aqueous phase and an organic phase comprising 3,3′,4,4′-tetramethylbenzophenone;
- b) separating the aqueous phase and the organic phase of step a);
- c) reacting the organic phase separated in step b) with a second aqueous nitric acid composition a pressure vessel in a fed batch reaction, feeding an aqueous nitric acid solution comprising from 30 to 70% by weight nitric acid to the pressure vessel over a period of from 1 to 10 h, increasing the reaction temperature during said feeding from an initial value in the range of from 110 to 130° C. to a final value in the range of from 140 to 180° C.;
- d) passing nitric oxide from the pressure vessel into an absorption vessel;
- and
- e) reacting the nitric oxide in the absorption vessel with molecular oxygen and water to produce an aqueous nitric acid solution.
A method for oxidizing a 1,1-bis-(3,4-dimethylphenyl)-alkane to 3,3′,4,4′-benzophenone tetracarboxylic acid, comprising the steps
- a) reacting the 1,1-bis-(3,4-dimethylphenyl)-alkane in a fed batch reaction, charging the 1,1-bis-(3,4-dimethylphenyl)-alkane and water or an aqueous nitric acid solution to a pressure vessel to provide a nitric acid content of no more than 15% by weight in the resulting mixture and feeding an aqueous nitric acid solution comprising from 30 to 70% by weight nitric to the pressure vessel over a period of from 1 to 10 h, increasing the reaction temperature during said feeding from an initial value in the range of from 90 to 110° C. to a final value in the range of from 140 to 180° C.;
- b) passing nitric oxide from the pressure vessel into an absorption vessel;
- c) reacting the nitric oxide in the absorption vessel with molecular oxygen and water to produce an aqueous nitric acid solution;
- and
- d) passing all or a part of the aqueous nitric acid solution produced in step c) to a subsequent batch of step a).
Dependencies are inferred from the claim text.