Patent ID: 8530675

Claim:
A process for the preparation of a compound of Formula 4: wherein R 1 is independently Cl or Br, R 2 , R 3 , R 4 and R 5 are I, R 6 is H, and R 11 and R 12 are independently H or a counter-ion capable of forming a pharmaceutically acceptable salt, comprising: a) combining a compound of Formula 1, wherein R 1 is independently Cl or Br, with about two equivalents of a compound of Formula 2, wherein R 7 , R 8 , R 9 and R 10 are H, in an acidic solution substantially free of chloride ions and substantially free of chloride-ion producing impurities, to an intermediate compound of Formula 3a, wherein R 1 is independently Cl or Br and R 2 , R 3 , R 4 , R 5 and R 6 are H; b) combining the intermediate compound of Formula 3a with at least about 4 equivalents of iodine in a solution substantially free of chloride ions and substantially free of chloride-producing impurities to form the compound of Formula 4 substantially free of transhalogenated impurities of the compound of Formula 4 wherein R 1 is independently Cl or Br; at least one of R 2 , R 3 , R 4 and R 5 is Cl and the remainder are I; R 6 is H; and R 11 and R 12 are independently H, Na, K, Li, or a counter-ion capable of forming a pharmaceutically acceptable salt.