Dissolution/filtration apparatus

Drop in the iodine solution from dropping funnel 4 while heating. Continue the heating for another 1-1.5 hours up to complete dissolution of the antimony. Let the solution stand overnight in the apparatus and on the following day filter off the crystals of antimony (III) iodide. If no crystals precipitated and unreacted antimony remains, heat the solution and filter it while hot through a paper filter on a funnel for hot filtration. 

Stopcock leading to the vacuum system is dosed, and the flask (still attached to the distillation apparatus) is placed in a constant temperature bath at 60°. The flask is occasionally swirled to aid in dissolution of AIBN and to recover AIBN, which condenses on the upper walls of the flask. The transition to a very viscous medium occurs in approximately 2 hr. At this point, the mixture is dissolved in 50 mL of dichloromethane and the resulting solution is dropped slowly down the wall of a 400-mL beaker containing 200 mL of stirred methanol. The polymer is allowed to settle, and most of the solvent is decanted. Approximately 200 mL of additional methanol is added and then decanted after the polymer has settled. The polymer is isolated by filtration through coarse filter paper, dried in an oven at 50°, and then placed in vacuo (0.02 torr) overnight. A yield of 0.27 g (12% conversion) is obtained. Conversions of 10 to 20% are typically achieved with higher conversions being possible with extended reaction times. 

Experiments were done, using a batch crystallizer apparatus as shown in Fig.l, varying the Mg/P molar ratio from 1-4. The experimental conditions are shown in Table 2. During the process of batch crystallization, the mixed suspension was sampled at the determined crystallization time. The samples were filtered through 0.45 fjL m membrane filter, and the concentrations in the filtrate were measured. Also sampled crystals were obtained when the concentration was observed to be constant, to be observed by SEM and be analyzed by the Xray diffractometer. The composition of crystals was analyzed after dissolution by a pH 2 HCl solution. 

The concentration of spironolactone (uniformity of the dose) in eaeh powder mixture was foimd by UV analysis (HACH DR500, HACXH Company, Loveland, CO) at 242 nm. A calibration curve was built at 2.5, 5, 10, 20 and 30 pg/mL concentrations. Dissolution studies were conducted employing an Erweka (DT6-K, Erweka GmbH, Milford, CT) type 2 apparatus containing IL of O.IN HCl and 0.1 % of sodium lauryl sulfate at 37°C and 75 rpm for Ih. At 5, 15, 30, 45 and 60 min, aliquots of ImL each, were taken, filtrated and diluted (200 pL/1 mL) before measurement. 

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