C19H29IO2 416.34

Benzenedecanoic acid,iodo-i-methyl-,ethyl ester.
Ethyl 10-(iodophenyl)undecanoate [1320-11-2].

Packaging and storage— Preserve in tight,light-resistant containers.Store at 25,excursions permitted between 15and 30.

Identification— Place about 1mLof Iophendylate,15mLof water,and 7g of potassium dichromate in a round-bottom,50-mLflask.Carefully add 10mLof sulfuric acid,moderating the ensuing vigorous reaction by cooling the flask with tap water.When the reaction has subsided,reflux the mixture for 2hours.Pour the cooled contents of the flask into 25mLof water,filter the mixture with suction,and wash the precipitate with a small quantity of cold water.Crystallize the precipitate from 10mLof diluted alcohol,and sublime the solid so obtained:the sublimate of p-iodobenzoic acid melts between 268and 272.

Specific gravity á841ñ: between 1.248and 1.257.

Refractive index á831ñ: between 1.524and 1.526.

Residue on ignition á281ñ: not more than 0.1%.

Free acids— Transfer about 4g,accurately weighed,to a small flask,and add 20mLof alcohol.Swirl to dissolve the test specimen,add 5drops of phenolphthalein TS,and titrate with 0.050Nalcoholic potassium hydroxide to a pink color that persists for 30seconds:not more than 0.60mLof 0.050Nalcoholic potassium hydroxide is required for neutralization,correction being made for the amount of 0.050Nalcoholic potassium hydroxide consumed by a blank (0.3%as iodophenylundecanoic acid).

Free iodine— Determine its absorbance in a 4-cm cell,at 485nm,with a suitable spectrophotometer,using water as the blank:the absorbance is not greater than 0.16(7.5ppm).

Saponification value— Transfer about 1g,accurately weighed,to a 250-mLflask,add 25.0mLof 0.5Nalcoholic potassium hydroxide VS,and reflux the mixture on a steam bath for 1hour.Cool,add 25mLof water and 0.7mLof phenolphthalein TS,and titrate with 0.5Nhydrochloric acid VS.The saponification value (see Fats and Fixed Oils á401ñ)is between 132and 142.

Assay— Dissolve about 50mg of Iophendylate,accurately weighed,in 5mLof toluene contained in a 125-mLseparator fitted with a suitable,inert plastic stopcock.Add 15mLof sodium biphenyl,and shake vigorously for 2minutes.Extract gently with three 10-mLportions of 5Mphosphoric acid,combining the lower phases in a 125-mLiodine flask.Add 1Nsodium hypochlorite dropwise to the combined extracts until the solution turns brown,and then add an additional 0.5mL.Shake intermittently for 3minutes,add 5mLof freshly prepared,saturated phenol solution,mix,and allow to stand for 1minute,accurately timed.Add 1g of potassium iodide,shake for 30seconds,and titrate rapidly with 0.1Nsodium thiosulfate VS,adding 3mLof starch TSas the endpoint is approached.Each mLof 0.1Nsodium thiosulfate is equivalent to 6.939mg of C19H29IO2.

Expert Committee:(RMI)Radiopharmaceuticals and Medical Imaging Agents

USP28–NF23Page 1048

Phone Number:1-301-816-8305