The Physical Basis of Optical Activity

This is one enantiomer of 3-methylhexane to emphasize chirality, a (+) [or (-)], or is sometimes added to the structure 

When it is the racemic mixture that is meant, sometimes (ij is added. However, this is not always done, and you must be alert for such times 

FIGURE 4.16 A variety of conventions is used to indicate the presence 

We have covered the way in which enantiomers differ from each other physically They rotate the plane of plane-polarized light in opposite directions. Before we go on to talk about how enantiomers differ in their chemical reactivity, let s take a little time to say something about the phenomenon of optical activity. How does a collection of atoms (a molecule) interact with a wave phenomenon (light), and how does the property of chirality (handedness) induce the observed rotation  

Light consists of electromagnetic waves vibrating in all possible directions perpendicular to the direction of propagation (Fig. 4.17). 

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