ËÄÉ«AV

The present invention pertains to a process for the prepn. of iodixanol and the purifn. of crude product through macroporous adsorption resin chromatog. column and recrystn. The synthesis method comprises reacting 5-acetylamino-N,N'-bis(2,3-dihydroxypropyl)-2,4,6-triiodoisophthalamide with epichlorohydrin for dimerization, wherein excessive side reactions such as alkylation are effectively inhibited by controlling the pH of the reaction mixt. with a boron-contg. acidic substance or salts thereof such as boric acid with conversion rate of 85 - 90 %. The iodixanol crude product can be purified by a macroporous adsorption resin chromatog. column, obtaining iodixanol product with recovery of 90 - 95 % and purity of 96 - 98 %. The iodixanol crude product can be recrystd. in mixed solvent contg. 2-methoxyethanol, obtaining iodixanol product with recovery of 90 - 95 % and purity of greater than 99 %.