Enantiomers rotate light the same amount

Enantiomers rotate light the same amount - optical rotation...

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Enantiomers rotate light the same amount, but in opposite directions. o So if one stereoisomer rotates light 4° to the right, then its enantiomer will rotate light 4° to the left. o It is important to understand that R/S configuration does not tell you whether you have the + or – enantiomer R/S configuration is a manmade convention, whereas +/- is a physical property. o It’s important to distinguish that R/S configuration has no relationship to +/-. 50/50 mixtures of enantiomers are called racemic mixtures or racemates. o These do not rotate plane-polarized light because the two enantiomers cancel each other out. Calculation of enantiomeric excess o We will not do this in this class. You are responsible for this in your lab lecture. o If you see a problem on the test which looks like it requires any sort of calculation with
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Unformatted text preview: optical rotation, then you need to look at the question again. For example, sometimes you’ll see a question like “which of the following would rotate light 1° clockwise?” followed by a series of solutions. • All but one of the answers will be achiral, so the answer is the only chiral answer. • You might have an achiral molecule, an equal mixture of enantiomers, an equal mixture of diastereomers, and another achiral molecule. • The correct answer would be the mixture of diastereomers because it is the only chiral solution given. o Chemical properties Chiral materials react with other chiral reactants selectively • Think of the glove and hand model here • If you have a bunch of right-handed gloves only right hands will fit. o Separation of enantiomers...
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Enantiomers rotate light the same amount - optical rotation...

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