Patent GB-815421-A (GB)
Title: Iodo-dextran and methods for producing the same
Inventor: NOVAK LEO J
IPC: C08B37/02
Filed: 1957-08-26
Abstract: The invention comprises Iodo-dextran.  The novel product may be prepared by dissolving or dispersing dextran in water, adding iodine or Lugol's solution (a 5 per cent solution of iodine in 10 per cent KI solution), allowing the mixture to react at room temperature or heating it at 50-80 DEG  C., with stirring until the iodo-dextran is formed.  Alternatively, the dextran is dispersed in an organic solvent which is a chlorine acceptor, such as pyridine, and containing a sulphonic acid chloride which reacts with the dextran, a major portion of the solvent is removed, the residue is dissolved in alcohol, the solution diluted with water and then neutralized, the alcohol is removed under vacuum, acetone is added, an alkali metal iodide is added and the mass is heated at 100-120 DEG  C. for 3 to 5 hours and the iodo dextran is recovered therefrom.  The dextran starting material may be native high molecular weight microbiologically produced dextran, or it may be a partial hydrolyzate of the native dextran, such as a water-soluble dextran of molecular weight in the "clinical" dextran range, i.e. molecular weight of 20,000 to 200,000 (average 60,000 to 80,000).  In general the dextran may have a molecular weight between 2000 and that of "native" dextran.  The molar ratio of dextran to iodine may be from 1 : 3 to 1 : 5.  Depending on the molecular weight of the dextran, the iodo dextran may be used externally, or for intravenous injection or as X-ray contrast media.  In examples: (1) native, unhydrolysed, wate-soluble dextran is dissolved in water, the solution is added to Lugol's solution with stirring and the mixture is allowed to stand for 12 hours or until the iodo-dextran is formed and the latter is precipitated with methanol, dissolved in water and re-precipitated with methanol; (2) a dispersion of "clinical" dextran in pyridine is cooled to - 5 DEG  C., p-toluene sulphonic acid is added, the mixture is allowed to stand for a half-hour and the pyridine is then distilled off under vacuum, the residue is dissolved in alcohol, water is added, the solution is neutralized with sodium hydroxide, the solvent is removed under vacuum, acetone is added and the solution is filtered and concentrated and sodium iodide is then added, the solution being heated at 100 DEG  C. for 4 hours to give iododextran; other sulphonic acid chlorides such as the acid chlorides of ethane-sulphonic, methanesulphonic or benzenesulphonic acids may also be used; (3) Example (2) is repeated using dextran of average molecular weight of 5000; (4) Example (2) is repeated using dextran of average molecular weight of 50,000 and ethane sulphonyl chloride.ALSO:Iodo-dextran obtained from native microbiologically-produced high molecular weight dextran may be used for external application as a disinfectant in aqueous solution or relatively dilute dispersion or as a paste.  For internal use, an iodo-derivative of a water soluble dextran in the "clinical" dextran range is suitable for intravenous injection.  The molar ratio of dextran to iodine may be from 1 : 3 to 1 : 15.  Aqueous solutions of these iodine-substituted dextrane may also be used as X-ray contrast media which cause the structure of the kidney to become visible under X-ray observation.  The products are non-irritating, stable and may be used for any of the purposes for which iodine is adapted.  (For preparation see Group IV (a).)