The present invention relates to a process for the preparation of iodinated X-ray contrast agents and in particular to key intermediates thereof. It particularly relates to an improved process for preparation of 5-acetamido-N,N'-bis(2,3-dihydroxypropyl)-2,4,6-triiodoisophthalamide (Compound A) or N,N'-bis(2,3-dihydroxypropyl)-5-formamido-2,4,6-triiodoisophthalamide (Compound C), which are intermediates in the industrial preparation of non-ionic X-ray contrast agents. More particularly the invention provides a process for deacylation of the acylated hydroxyl groups of an intermediate compound of Compound A and Compound C.
