CH 220 1st Edition Lecture 15Outline of Current Lecture I. Stereochemistry at tetrahedral centers – enantiomers II. Naming enantiomersCurrent LectureI. Stereochemistry at tetrahedral centers – enantiomers Molecules that have 1 carbon and 4 different substituents have a non-superimposable mirror image – enantiomersSuch carbon atoms are stereocenters or chiral moleculesCHXYZThis results in right and left hand versionsFirst discovered by Louis Pasteur II. Naming enantiomersUses priority system, like EZ1. Rank 4 different substituents by atomic number and build with model kit2. Hold the lowest priority substituent facing away from you and look at the remaining 3 groups on a plane3. If the priorities 1,2,3 are clockwise then it is designated R (right)4. If the priorities 1,2,3 are counter-clockwise then it is designated S (left)5. If a decision cannot be reached by ranking the first atoms in the substituents, look at the second, third or fourth until there is a difference You should always build the molecule to making it easier to figure out designation (R or S) put a blue substituent on 1st priority, red on 2nd priority, yellow on 3rd priority and white on 4th priority. Once you have built it by looking at the diagram given, hold the white substituent away from you and look at the remaining three colors to assess.These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.If you forget which colors are which priorities, think of alphabet: Blue – Red – Yellow are in alphabetical order (white doesn’t count).These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a
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