Preparation of polyphenols by oxidation of hydroxybenzaldehydes
AssigneeRhone-Poulenc Industries
InventorsKarel Formanek, Daniel Michelet, Dominique Petre
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Abstract
Optionally aldehyde substituted polyphenols are prepared by oxidizing, with hydrogen peroxide, a hydroxybenzaldehyde bearing at least one aldehyde substituent ortho- and/or para- to the nuclear hydroxyl group, in an aqueous reaction medium and in the presence of an alkali or alkaline earth metal base, the process being characterized in that the pH of the reaction medium is continuously maintained at a value no greater than 7 throughout the course of the oxidation reaction. The subject process is well suited for the preparation of, e.g., hydroxy-p-vanillin from guaiacol, and the novel compound 2,4,6-triformylphenol.
Claims36
In a process for the preparation of optionally aldehyde substituted polyphenols by oxidizing, with hydrogen peroxide, a hydroxybenzaldehyde bearing at least one aldehyde substituent ortho- and/or para- to the nuclear hydroxyl group, in an aqueous reaction medium and in the presence of an alkali or alkaline earth metal base, the improvement comprising maintaining the pH of the said reaction medium in the range of from about 2 to 7 throughout the course of the oxidation reaction, with the hydrogen peroxide and an alkali metal base or alkaline earth metal base being added gradually to the reaction medium, whereby at least one formyl of the hydroxybenzaldehyde is oxidized to a hydroxyl.
Dependencies are inferred from the claim text.