GB823360A - Iodo-carboxymethyl dextran and method of making it - Google Patents

Abstract

The invention comprises iodo-carboxymethyl dextran containing per anhydroglucose unit an average of 0.5 to 2 carboxymethyl groups and in which an average of 1.0 to 2.5 of the hydroxyl groups present initially in the carboxymethyl dextran are replaced by iodine. The iodo-carboxymethyl dextran may be prepared by dissolving in water the carboxymethyl dextran containing, per anhydroglucose unit, an average of 0.5 to 2 carboxymethyl groups, adding powdered crystalline iodine or Lugol's solution (5% iodine in 10% KI) to the solution with stirring and allowing the mixture to react at room temperature or heating it until the iodo-carboxymethyl dextran is formed. Alternatively the carboxymethyl dextran is dispersed in a solution of a sulphonic acid chloride in an organic solvent which is a chlorine acceptor, such as pyridine, whereby the sulphonyl chloride of carboxymethyl dextran is formed. A major portion of the solvent is then removed, for example by distillation, the residue is dissolved in alcohol, the solution is neutralized, the alcohol is removed under vacuum and acetone is added, an alkali metal iodide such as sodium or potassium iodide is added to the acetone solution and the mass is heated at 80-120 DEG C. for 3 to 5 hours until iodo-carboxymethyl dextran is formed. The carboxymethyl dextran starting material may be derived from native, high molecular weight dextran, or from a partial hydrolyzate of the native dextran, or from clinical dextran. It may be obtained by reacting the selected dextran with a carboxymethylating agent such as chloracetic acid, sodium chloracetate or chloracetamide, in water containing strong alkali metal hydroxide, preferably at 50-100 DEG C. for 10 minutes to 2 hours, and precipitating the alkali metal salt of the dextran ether by means of a water-miscible aliphatic alcohol or ketone. The salt is dissolved in water, acidified to pH 2.0-3.0 and the free ether is precipitated with a water-miscible alcohol or acetone. The iodocarboxymethyl dextran may be used as a disinfectant and as X-ray contrast media.ALSO:Aqueous solutions of iodo-carboxymethyl dextran containing per anhydroglucose unit an average of 0.5 to 2 carboxymethyl groups and in which an average of 1 to 2.5 of the hydroxyl groups initially present in the carboxy methyl dextran per anhydroglucose unit are replaced by iodine (for preparation see Group IV (a)), may be used as X-ray contrast media. The iodo-carboxymethyl dextran may be derived from native dextran, a partial hydrolygate of dextran or clinical dextran.