Potassium Carbonate → 10-(4,4-Dimethyl-3-oxa-pentyl)-1,4,7-tris-(carboxymethyl)-1,4,7,10-tetraazacyclododecane

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Reaction Steps

5 g (14.43 mmol) of 1,4,7-tris-(carboxymethyl)-1,4,7, 10-tetraazacyclododecane is stirred in 75 ml of dimethylformamide for 18 hours with 3.14 g (17.35 mmol) of (2-bromoethyl)-tert-butyl ether and 6.50 g of potassium carbonate at 95° C. It is concentrated by evaporation in a vacuum and the residue is dissolved in 100 ml of water, the pH is adjusted to 2 by adding 12 N hydrochloric acid and the solution is put on a column of 320 ml of cation exchanger IR-120 (H+ form). It is eluted with 2 l of water, which is discarded, then with 2 l of 0.5 N ammonia solution. This solution is concentrated by evaporation in a vacuum, the residue is dissolved in 100 ml of water. With stirring, enough cation exchanger IR-120 is added in portions up to pH 3.5. The solution is filtered and freeze-dried and 4.19 g of the title compound is obtained as white solid with a water content of 6.3%.

Provenance & Evidence