Method of preparing 5-amino salicylic acid
AssigneeNobel Kemi AB
InventorUlf Sjostrand
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Abstract
The disclosure relates to a method of producing 5-amino salicylic acid from salicylic acid, with sulphanilic acid as the recyclable auxiliary chemical. The method according to the present invention includes linking between the diazonium salt of the sulphanilic acid and the salicylic acid, followed by a splitting by hydrogenation with hydrogen gas and catalyst, and selective precipitation of the desired product.
Claims7
A method of producing 5-amino salicylic acid with sulphanilic acid as auxiliary chemical, characterized in that 5-(p-sulphophenyl azo) salicylic acid, produced by linking of the double sodium salt of the salicylic acid with a diazonium salt of sulphanilic acid, is split by hydrogenation with hydrogen gas and a catalyst at elevated pressure and temperature in excess of 50.degree. C., whereafter the thus obtained 5-amino salicylic acid is precipitated from the mother liquor by acidification thereof.
Dependencies are inferred from the claim text.