Transcript Chapter 15 The Three-Dimensional Shape of Molecules

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
I. Review
A. Isomers
B. Constitutional Isomers
C. Stereoisomers
1. Cis and trans molecules
3-D Molecules
II. Chirality
Achiral
example
Which of the following objects are chiral?
3-D Molecules
3-D Molecules
III. Enantiomers and Chirality Centers
•A carbon atom with four different groups like
CHBrClF is called a chirality center.
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.
3-D Molecules
•Is C1 a chirality center?
•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.
3-D Molecules
IV. Racemic Mixtures
•A racemic mixture is an equal mixture of two
enantiomers.
3-D Molecules
V. Fischer Projections
3-D Molecules
VI. Multiple Chirality Centers (Stereocenters)
VII. Optical Activity / Specific Rotation
3-D Molecules