4-Aminosalicylic Acid → 2-Hydroxy-4-iodobenzoic acid

Participants

Reaction Conditions

Reaction Steps

To 20% sulfuric acid solution (650 ml) were added 4-amino-2-hydroxybenzoic acid and 200 ml of 20% sulfuric acid solution. The solution was cooled to −10° C. and a solution of sodium nitrite (47 g, 0.34 mol) in water (100 ml) was added over 5 hours. The solution obtained was added dropwise to a suspension of potassium iodide (69.5 g, 0.42 mol) and copper(I) iodide (69.5 g, 0.36 mol) in 370 ml of 20% sulfuric acid. The mixture was stirred for 36 hours at room temperature and was then filtered. The filtrate was extracted with ethyl acetate, washed twice with saturated sodium sulfite solution and twice with water. The organic phase was concentrated on a rotary evaporator under vacuum at 40° C. The properties of the final product were as follows:

Provenance & Evidence