Chapter 15 The Three-Dimensional Shape of Molecules CHEM 2124 – General Chemistry II Alfred State College Professor Bensley

Learning Objectives  Recognize whether a molecule is chiral or achiral.  Identify chirality centers.  Draw two enantiomers in three dimensions around the chirality center.  Explain why some chiral drugs have very different properties from their mirror images.  Draw Fischer projection formulas.  Recognize the difference between enantiomers and diastereomers.  Explain the relationship between the shape and odor of a molecule.

3-D Molecules A.Isomers B.Constitutional Isomers C.Stereoisomers 1.Cis and trans molecules I.Review

3-D Molecules II.Chirality Achiral example

Which of the following objects are chiral?

3-D Molecules

A carbon atom with four different groups like CHBrClF is called a chirality center. 3-D Molecules III.Enantiomers and Chirality Centers

Drawing a Pair of Enantiomers HOW TO Draw Two Enantiomers of a Chiral Compound Example Draw two enantiomers of 2-butanol in 3D around the chirality center.

Is C1 a chirality center? 3-D Molecules Is C3 a chirality center:

Focus on Health & Medicine The Unforgettable Legacy of Thalidomide The anti-nausea drug thalidomide, which was given to pregnant women in the early 1960’s had a chirality center.

A racemic mixture is an equal mixture of two enantiomers. 3-D Molecules IV.Racemic Mixtures

3-D Molecules V.Fischer Projections

3-D Molecules VI.Multiple Chirality Centers (Stereocenters) VII. Optical Activity / Specific Rotation

3-D Molecules