Solve Example 17-15 Part E calculating the solution density by assuming that volumes add. Determine the error in the amount of crystals collected by comparing your answer to the answer determined with experimental density data. Data are in Figure 17-23.

Example 17-15

100.0 L of saturated lovastatin dissolved in pure acetone at 25.0C is to be crystallized by adding water, which is an antisolvent, and/or by cooling. First, we add enough water to reduce the acetone in solution to 80.0 vol%. A. How many liters of water do we add? B. What is the volume of the 80.0% solution? C. How many kg of lovastatin crystallize from the 80.0% solution and what is the yield? Why is the yield so low? D. If instead of adding water we cool the initial 100.0 L of 100.0% acetone solution to 20.0C, what weight of crystals are formed and what is the yield? E. If the initial feed has water added to create an 80.0 vol% acetone solution at 25C and the solution is then cooled to 20.0C, what weight of crystals are formed, and what is the yield of lovastatin? Data: MW acetone = 58.08, MW water = 18.016, at 25C Pacetone = 0.785 g/ml and pw 0.9971 g/ml. At 20.0C Pacetone = 0.791 g/ml and pw = 0.99816 g/ml. Densities of acetone water solutions at different weight fractions acetone and different temperatures are shown in Table 17-5. Lovastatin solubility data in solutions of acetone and water is shown in Figure 17-23. Assume lovastatin does not change densities of solutions. TABLE 17-5. Densities of Solutions of Acetone and Water TC Wt. frac. Acetone 20.0 20.0 20.0 25.0 25.0 25.0 25.0 37.78 37.78 37.78 37.78 0.9231 0.7564 0.5193 0.9293 0.7501 0.6642 0.5220 0.91283 0.7641 0.6565 0.5182 Vol. 0.9382 0.7970 0.5773 0.9435 0.7922 0.7152 0.5811 0.9299 0.8041 0.7077 0.5768 frac. Acetone Pmixture 0.8134 0.8593 0.9161 0.8063 0.8562 0.8784 0.9110 0.7965 0.8392 0.8674 0.9002 g/ml Mol% data in Thomas and McAllister (1957) was converted to weight and volume fractions. Note 37.78C = 100.00F. Solubility (mg Lov/ml solution) 100 x 100 vol% + 80 vol% 80 0 60 40 20 70 vol% 50 vol% trendlines 0 10 20 30 Temperature (C) 40 50