week 2 - 1 - Symmetry, Chirality, and Enantiomers N.B. Many...

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Unformatted text preview: Symmetry, Chirality, and Enantiomers N.B. Many of these slides have been borrowed from Prof. Garry Procter. Reading : Section 6.1 Chemistry S-20ab Week 2 81 Chemistry S-20ab Week 2 82 Some Important Vocabulary Words Enantiomers : stereoisomers that are non-superimposable mirror images Chirality : the property of having a non-superimposable mirror image How can I tell if a molecule is chiral? 1. Does it have a stereogenic center? Generalizations: ! If a molecule has 0 stereogenic centers, it is achiral . ! If a molecule has a single stereogenic center, it is chiral . ! If a molecule has >1 stereogenic centers, we must consider another property. CH 3 OH H 3 C CH 3 OH OH H H CH 3 OH H H 3 C 2. Is there an internal plane of symmetry in the molecule? Any molecule that has a plane of symmetry will be achiral. Any molecule that lacks a plane of symmetrty will be chiral . For each of the following molecules, determine whether it is chiral or achiral. If it is chiral, draw its enantiomer. H 3 C OH H F Cl Br H 3 C OH Reading : Section 6.1 !"#$%& (%"%)*#+,-. /0+ ! 1 " 23-4+# Here are the rules for naming enantiomers: Assign R or S conFgurations to each of the following compounds: Br H F Cl H Cl OH CH 3 C H 2 H OH CH 3 H CH 2 H 3 C H 3 C 1 2 OH H 3 C H H 2 C 3 4 CH 3 4 3 2 1 2. OH CH 3 H CH 2 H 3 C 1. Rank the groups attached to the stereocenter in priority order - as for E & Z nomenclature of alkenes. The greater the atomic number, the greater the priority. Use the first point of difference where necessary. Orient the molecule (re-draw if necessary) so that it is viewed with the lowest priority group is directed away from viewer (i.e. the bond to 4 is dashed)....
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This note was uploaded on 07/21/2010 for the course CHEM S20ab taught by Professor Mccarty during the Summer '10 term at Harvard.

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week 2 - 1 - Symmetry, Chirality, and Enantiomers N.B. Many...

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