Originator
Conray,Mallinckrodt Inc.,US,1962
Manufacturing Process
Crude 5-amino-2,4,6-triiodo-N-methylisophthalamic acid (21.0 g) was
dissolved in warm dimethylacetamide (40 ml) and acetic anhydride (30 ml)
and concentrated sulfuric acid (2 drops) were added. This solution was heated
on the steam bath for 2 hours, then heated at 110°C for 5 minutes, then
cooled. Water and ammonium hydroxide were added to destroy the excess
acetic anhydride, after which the mixture was evaporated to a volume of 50
ml. The cooled solution was acidified with concentrated hydrochloric acid and
a tan solid was collected. The crude product was dissolved in 100 ml of water
containing a slight excess of sodium hydroxide. The pH was adjusted to 4.5
with acetic acid, and the solution was treated with charcoal. The colorless
solution was acidified with concentrated hydrochloric acid and cooled, and the
precipitate was filtered off and dried under reduced pressure. The resulting 5-
acetamido-2,4,6-triiodo-N-methylisophthalamic acid decomposes about 285°C
and does not melt below 300°C.
5-acetamido-2,4,6-triiodo-N-methylisophthalamic acid was slurried in water
and dissolved by the addition of an equivalent quantity of N-methylglucamine.
The solution was evaporated to dryness to yield the meglumate salt of 5-
acetamido-2,4,6-triiodo-N-methylisophthalamic acid.
