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AssigneeBayer Aktiengesellschaft
InventorsChristoph Jupe, Helmut Waldmann, Jurgen Baumert, Gunther Schummer
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A process for the isolation of hydroquinone, pyrocatechol, phenol and carboxylic acid from the reaction mixture containing the same such as one obtained by reaction of phenol with percarboxylic acid is disclosed. The reaction mixture is fed to a first rectification column and subjected to distillation whereby there is obtained a bottoms product containing pyrocatechol, hydroquinone and phenol. The top product is largely condensed and recycled, there being withdrawn from the top of the rectification column a mixture comprising phenol and carboxylic acid. The phenol and carboxylic acid mixture are continuously fed to a second rectification column where carboxylic acid is separated from phenol and substantially pure phenol is withdrawn from the stripping section and/or bottom of the second rectification column.
In a process for the recovery of pyrocatechol and hydroquinone from a reaction mixture obtained by reacting phenol with a percarboxylic acid having 1 to 4 carbon atoms at a molar ratio of phenol to percarboxylic acid, before the reaction, of 5 to 50:1 in which the reaction mixture comprising unreacted phenol, carboxylic acid corresponding to the percarboxylic acid, pyrocatechol and hydroquinone is worked up in a plurality of rectification apparatuses, the improvement wherein:
In a process for the recovery of pyrocatechol and hydroquinone from a reaction mixture obtained by reacting phenol with a percarboxylic acid having 1 to 4 carbon atoms at a molar ratio of phenol to percarboxylic acid, before the reaction, of 5 to 50:1 in which the reaction mixture comprising unreacted phenol, carboxylic acid corresponding to the percarboxylic acid, pyrocatechol and hydroquinone is subjected to a further treatment and then worked up in a plurality of rectification apparatuses, the improvement wherein:
Dependencies are inferred from the claim text.