Which of the following statements correctly pertains to a pair of enantiomers? A) They rotate the plane of polarized light by exactly the same amount and in opposite directions. B) They rotate the plane of polarized light by differing amounts and in opposite directions. C) They rotate the plane of polarized light by differing amounts and in the same direction. D) The have different melting points. E) They have the same melting point, but they have different boiling points.
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Can one predict whether a compound with a single asymmetric carbon is dextro- or levorotatory based on the R/S assignment at this asymmetric carbon? Explain briefly
No. R/S assignment is purely a convention of nomenclature and is completely independent of the direction in which plane-polarized light is rotated by the compound
) If (S)-glyceraldehyde has a specific rotation of -8.7°, what is the specific rotation of (R)-glyceraldehyde?
A newly isolated natural product was shown to be optically active. If a solution of 2.0 g in 10 mL of ethanol in a 50 cm tube gives a rotation of +2.57°, what is the specific rotation of this natural product?
The specific rotation of pure (-)-2-butanol is -13.5°. What % of a mixture of the two enantiomeric forms is the (+)-form if the specific rotation of this mixture is +7.0°?
(-)-Lactic acid has a specific rotation of -3.8°. What is the specific rotation of a solution containing 7.5 g of (-)-lactic acid and 2.5 g of (+)-lactic acid?
Calculate the e.e. of a mixture containing 8.0 g of (-)-glyceraldehyde and 2.0 g of (+)-glyceraldehyde.
Yes. The presence of asymmetric carbons is not required for a molecule to be chiral. The only requirement is that the molecule be nonsuperimposable with its mirror image. Structural features other than asymmetric carbons can lead to chirality.
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If the absolute configuration at an asymmetric carbon does not change during the course of a reaction, the reaction is said to occur with __________ of stereochemistry
__________ is the use of an optically active reagent or catalyst to convert an optically inactive starting material into an optically active product.