[单选题]
The structural formulae of t
, de(:f,1 xkqjfo wp7kue*r7t hree
+bcr;nn6 hpb6 c

ompounds are shown.
A student measures the optical activities of the three compounds using a polarimeter. Which of the following results are they most likely to obtain?
A. Activity of 1 / degrees is 3.0 ; Activity of 2 / degrees is 5.0 ; Activity of 3 / degrees is 3.2
B. Activity of 1 / degrees is 3.0 ; Activity of 2 / degrees is -5.0 ; Activity of 3 / degrees is 0.0
C. Activity of 1 / degrees is 5.0 ; Activity of 2 / degrees is 5.0 ; Activity of 3 / degrees is 3.2
D. Activity of 1 / degrees is 5.0 ; Activity of 2 / degrees is -5.0 ; Activity of 3 / degrees is 0.0
参考答案:
D
本题详细解析:
Explanation:
1 and 2 are enantiomers, exhibiting opposite optical activities (rotate plane polarised light in opposite directions by the same amount).
Compound 3 is achiral, so it has a rotation angle of 0 degrees.
This question is in the “hard” category, as the student must be able to determine a molecule's chirality and recall how polarimetry can be used to distinguish between stereoisomers.