Purification Methods
The chloride can be purified in the same way as the bromide, and it can be prepared from the iodide. A few milligrams dissolved in H2O can be purified by applying onto a Dowex-1 Cl-resin column (prepared by washing with N HCl followed by CO3 -free H2O until the pH is 5.8). After equilibration for 10minutes, elution is started with CO3 -free distilled H2O, and 3mL fractions are collected and their OD values at 229nm are measured. The fractions with appreciable absorption are pooled and lyophilised at 0-5o. Note that at higher temperatures decomposition of the ester is appreciable; hydrolysis is appreciable at pH >10.5/20o. The residue is dried in vacuo over P2O5, checked for traces of iodine (add conc H2SO4 and heat, violet vapours are released), and recrystallise it from propan-1-ol. [Gal & Roth Clin Chim Acta 2 316 1957, Beilstein 4 IV 1585.]
