Continuous manufacture of anthranilic acid
AssigneeBASF SE
InventorsGerhard Kilpper, Johannes Grimmer
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Abstract
Anthranilic acid is manufactured continuously by reacting an alkali metal phthalamate and/or phthalimidate with an alkali metal hypohalite in a reaction tube, the resulting anthranilic acid being treated, during or after the reaction, with reducing agents in two steps, the reducing agents employed in the two steps being different from one another, and an alkali metal dithionite or alkali metal formaldehyde-sulfoxylate being used as the reducing agent in the second treatment step. The product is a starting material for the preparation of dyes, crop protection agents and scents.
Claims15
A process for the continuous manufacture of anthranilic acid by reacting an alkali metal phthalamate, phthalimidate, or a mixture thereof, with a hypohalite in an aqueous medium in a reaction tube, wherein, during the reaction forming the anthranilic acid or after completion of the reaction,
- (1) in a first step, the anthranilic acid so obtained is treated with reducing agents which are not alkali metal dithionite or alkali metal formaldehyde-sulfoxylates and
- (2) in a second step the treated anthranilic acid is then further treated with an alkali metal dithionite, an alkali metal formaldehyde-sulfoxylate or a mixture thereof.
Dependencies are inferred from the claim text.