| In this thesis, the solubility of dexibuprofen and ibuprofen in isopropyl alcohol, ethanol absolute, ethyl acetate, n-hexane were determined via the balance method using UV-vis spectrophotometer as the analytical instrument. The solubility data were correlated with the solid-liquid balance equation. Then the crystal habit and size distribution of dexibuprofen were studied under different crystallization conditions, such as solvents, cooling rate, supersaturation, crystallization temperature, crystallization time, and so on. Major results were shown as below:Within the experiment limits, the solubility of dexibuprofen in isopropyl alcohol, ethanol absolute, ethyl acetate, n-hexane was larger than the solubility of ibuprofen under the same condition. The solubility of the dexibuprofen and ibuprofen increased with the temperature, but the increasing rates were different. Different solvents had different effects on the increasing rate of the solubility with the temperature. The solubility data were correlated with the solid-liquid balance equation. The experimental values agreed well with the regression values and the relative error between them was small.Solvent had a great influence on the crystal habit of dexibuprofen, while cooling rate, supersaturation, crystallization temperature and crystallization time affected mainly the crystal size distribution. As a result, within the experiment limits, we obtained the optimal crystallization conditions: isopropanol as the solvent; cooling rate =0.5℃/ min; supersaturation=1.05; crystallization temperature=0℃; the crystallization time=3 h. Under these conditions, the average diameter of crystal was 34.85μm, the crystals of size between 19.31μm and 76.32μm accounted for 81.05 %, the maximum diameter of the crystals was 88.91μm. Compared with the raw material, both crystal habit and size distribution of the crystals have been greatly improved.
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