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crystals. Filtration, oven drying at 40 °C, and solid-state
characterization for Form II crystals were then implemented.
The yield is about 65 mol % (practically obtained/theoretical
amount = 42 g (0.28 mol)/65 g (0.43 mol) × 100%).
Solubility Values Measurement. About 20 mg of solid
samples of acetaminophen Form I or Form II were weighed in
a 20 mL scintillation vial. Drops of water, 3.22 M acetic
acid(aq), and 3.0 M sodium acetate(aq) were titrated carefully
by a micropipet into the vial separately with intermittent
shaking until all solids were just dissolved. The solubility value
of solids in a solvent or solution at a given temperature was
calculated as the weight of solids divided by the total volume of
solvent or solution added to a vial. Solubility values of solids in
a solvent or solution at five different temperatures of 7, 25, 40,
60, and 80 °C were determined in a water bath. Although the
gravimetric method36 appeared to have an inherent inaccuracy
of about 10%, its advantages were its robustness, simplicity,
without the need of performing any calibration, and the
concern of solvate formation. All measurements were repeated
at least three times.
AUTHOR INFORMATION
■
Corresponding Author
*Phone: +886-3-422-7151 ext. 34204. Fax: + 886-3-425-2296.
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
This research was supported by the grants from the National
Science Council of Taiwan, R.O.C. (Grant 102-2221-E-008-
071-MY2). We are greatly indebted to Ms. Jui-Mei Huang, Ms.
Shew-Jen Weng, and Ms. Ching-Tien Lin for their assistance
with DSC, PXRD, and SEM at the Precision Instrument Center
in National Central University, Taiwan R.O.C.
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ASSOCIATED CONTENT
* Supporting Information
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S
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Hermann, A.-M. J. Therm. Anal. 1997, 48, 447−458.
Materials, instrumentations, Figures S1−S6, and Tables S1−S3.
This material is available free of charge via the Internet at
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