For your un Review Questions
2. Describe how a polarimeter measures optical rotation.
b. A sample of pure (S)-2-butanol was placed in a 10.0 cm polarimeter tube. Using the D line
of a sodium lamp, the observed rotation at 20°C was +1049. The density of this compound is
0.805 g ml! What is the specific rotation of (S)-2-butanol?
c. Calculate the observed rotation of a solution of 0.5245g of (S)-1-amino-1-phenylethane
diluted to a volume of 10.0 mL with methanol at 20°C, using the D line of a sodium lamp
and a 1.00 dm tube. Specific rotation of this material: [] D23 = -30.09
d. What is the expected observed rotation of a 1.0 x 10-4 M methanol solution of the potent
anticancer drug paclitaxel (also called Taxol)? []d2° = -49° (c = 1, CH3OH). Paclitaxel has a
molecular weight of 853.93 g mole-?
e. A certain compound has a specific rotation of -43.2° (c = 5, toluene). What is the observed
rotation of a sample of 1.24 g of the enantiomer of this compound when diluted to a
g concentration of 1.00 gml in the same solvent?
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