2,4,6-Triiodobenzoate

Chemical Name 3-(Acetylamino)-2,4,6-triiodobenzoic acid sodium salt Common Name —... 

There were obtained 109 g 3-acetylaminomethyl-5-amino-2,4,6-triiodobenzoic acid which decomposes and melts at approximately 230°C. The equivalent weight was determined experimentally as being 591, as compared to a theoretical value of 586. 

Amino-2,4,6-triiodobenzoic acid 3,6,9-Trioxaundecane diacid dichloride... 

Diacetamldo-2,4,6-triiodobenzoic acid (diatrizoic acid) (see Diatrizoate entry for synthesis) (10 g) is suspended in water (10 ml), 5 N potassium hydroxide (4.3 equivalent) is added and the mixture cooled to about 15°C. Dimethyl sulfate (0.5 equivalent) dissolved in an equal volume of acetone is added drop by drop while stirring. After the reaction mixture has... 

CN 3,3 -[(l,6-dioxo-l,6-hexanediyl)diimino]bis[2,4,6-triiodobenzoic acid] disodium salt... 

CN 3-(acetylamino)-5-[(acetylamino)methyl]-2,4,6-triiodobenzoic acid meglumine salt... 

CN 3-[[[[3-(acetylmethylamino)-2,4,6-triiodo-5-[(methylamino)carbonyl]benzoyl]amino]acetyl]amino]-5-[[(2-hydroxyethyl)amino]carbonyl]-2,4,6-triiodobenzoic acid... 

FIGURE 9.18 Transformation of 3,5-diacetamido-2,4,6-triiodobenzoate by Trametes versicolor. (From Neilson, A.H. and Allard, A.-S., The Handbook of Environmental Chemistry, Vol. 3R, Springer Verlag, 2002, pp. 1-74. With permission.)... 

AT- 8,y-dihydroxypropyl-acetyl-amino)-5-acetylaminomethyl-2,4,6-triiodobenzoic acid I-l US3867431 Zutter/Bracco 10... 

In 2,4,6-triiodobenzoic acid derivatives iodine is firmly bound. Nowadays diamides of the 2,4,6-triiodo-5-acylamino-isophthalic acid like iopromide (Ultravist, Fig. 1) are used as non-ionic (neutral) X-ray contrast agents in most cases [1]. 

Amino-2,4,6-triiodobenzoic acid (51.5 g) was mixed with 125 ml of acetic anhydride containing 2 drops of concentrated sulfuric acid and refluxed for thirty minutes. The mixture was allowed to cool slightly, and then was poured into 600 ml of water at room temperature and stirred until crystallization was complete. The mixed anhydride of 3-acetylamino-2,4,6-triiodobenzoic acid with acetic acid thus prepared was then separated by filtration and washed with water. Without drying, the solid was suspended in 600 ml of water and hydrolyzed with a slight excess of ammonium hydroxide. It was necessary to warm the mixture slightly and stir it for about one-half hour in order to dissolve all the solid. The solution was then treated with activated carbon, filtered and precipitated with an excess of hydrochloric acid, filtered, washed and dried at 70°C. The yield was 51.5 g of 3-acetylamino-2,4,6-triiodobenzoic... 

The salt was dissolved in 300 ml water, and insoluble matter was removed from the solution by filtration. The free acid was precipitated from the filtrate at 50°C to 60°C by the addition of 40 ml 1 1 hydrochloric acid. The precipitate was filtered off after a few hours, washed with water, and dried. There were obtained 34 g 3-acetylaminomethyl-5-acetylamino-2,4,6-triiodobenzoic acid (79% of theoretical yield) having a melting point of 246°C to 248°C. The equivalent weight of this practically pure acid was found to be 631 as compared to the calculated value of 627.96. 

The ammonium salt was filtered off and dissolved in water (140 ml), charcoaled twice at 80°C and the acid was precipitated at room temperature by addition of hydrochloric acid and was filtered off. The crude product was dissolved in ethyl acetate (100 ml) and the solution was washed 3 times with hydrochloric acid (2 N). By evaporating the solvent, 19 g of 3-amino-5-methoxycarbonyl-2,4,6-triiodobenzoic acid was isolated. Melting point 170°-176°C. 

A mixture of 3-amino-5-methoxycarbonyl-2,4,6-triiodobenzoic acid (198 g) and thionyl chloride (400 ml) was heated while stirring at 70°C for 16 h. The solid material dissolved slowly. Thionyl chloride was evaporated in vacuo, the residue dissolved in chloroform (1000 ml), the solution washed with water (80 ml each), twice with saturated sodium bicarbonate, then 5 times with 2 N sodium hydroxide solution and finally with water to neutral. The solution was dried with CaCI2 filtered and evaporated to dryness. The 3-amino-5-methoxycarbonyl-2,4,6-triiodobenzoyl chloride was dried at 50°C in vacuo. Yield 203.0 g. Melting point 55°-60°C. 

The precipitate is filtered, washed and suspended moist in 4 parts of water, concentrated ammonia is added to pH about 7 and the ammonium salt solution is isomerized at 90°C to 100°C for about one-half hour whereafter additional ammonia is added to pH about 9 followed by solid ammonium chloride (about 10% weight/volume) and the solution stirred overnight and the excess of 3,5-diacetamide-2,4,6-triiodobenzoic acid recovered as ammonium salt on the filter. The filtrate is precipitated by means of hydrochloric acid (1 1 ) at pH about 0.5 and the N-methyl-3,5-diacetamido-2,4,6-triiodobenzoic acid collected on a filter, washed and dried. 

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