Lecture Note -1
Organic Chemistry CHE 502
STEREOCHEMISTRY- I
Dr. SHALINI SINGH
DEPARTMENT OF CHEMISTRY
UTTARAKHAND OPEN UNIVERSITY
, UNIT 1
BASIC CONCEPTS OF STEREOCHEMISTRY
Unit Structure
1.1 Introduction
1.2 Objectives
1.3 Stereochemistry- Definition
1.4 Terminology used in stereochemistry
1.5 Representation of three dimensional molecules
1.6 Element of symmetry
1.7 Nomenclature
1.8 Summary
1.9 Glossary
1.10 Check your progress
1.11 Bibiliography
1.12 Suggested readings
1.13 Terminal Questions
1.1. INTRODUCTION:
Stereochemistry deals with three dimensional representation of molecule in space. This
has sweeping implications in biological systems. For example, most drugs are often
composed of a single stereoisomer of a compound. Among stereoisomers one may have
positive effects on the body and another stereoisomer may not or could even be toxic. An
example of this is the drug thalidomide which was used during the 1950s to suppress the
morning sickness. The drug unfortunately, was prescribed as a mixture of stereoisomers, and
while one stereoisomer actively worked on controlling morning sickness, the other
stereoisomer caused serious birth defects.
The study of stereochemistry focuses on stereoisomers and spans the entire spectrum of
organic, inorganic, biological, physical and especially supramolecular chemistry.
Stereochemistry includes method for determining and describing these relationships; the
effect on the physical or biological properties.
, So to have the sound knowledge of stereochemistry we should have good command over their
basic concepts.
1.2. OBJECTIVES:
• Classification of stereoisomers
• Recognize a stereogenic (chiral) center in a molecular structure
• Various representation of three dimentional molecules
• To be able to predict, identify and distinguish between enantiomers and diastereomers.
• Various nomenclature of stereoisomers to define them properly
1.3. STEREOCHEMISTRY: DEFINITION
The branch of chemistry which deals with three dimensional structure of molecule and their
effect on physical and chemical properties is known as stereochemistry. To represent
molecule as three dimensional object we need at least one carbon sp3- hybridized.
Example:
H
Cl
2D drawing Not appropriate for steriochemistry
I Br
H
3D drawing appropriate for steriochemistry
Cl
I Br
Organic Chemistry CHE 502
STEREOCHEMISTRY- I
Dr. SHALINI SINGH
DEPARTMENT OF CHEMISTRY
UTTARAKHAND OPEN UNIVERSITY
, UNIT 1
BASIC CONCEPTS OF STEREOCHEMISTRY
Unit Structure
1.1 Introduction
1.2 Objectives
1.3 Stereochemistry- Definition
1.4 Terminology used in stereochemistry
1.5 Representation of three dimensional molecules
1.6 Element of symmetry
1.7 Nomenclature
1.8 Summary
1.9 Glossary
1.10 Check your progress
1.11 Bibiliography
1.12 Suggested readings
1.13 Terminal Questions
1.1. INTRODUCTION:
Stereochemistry deals with three dimensional representation of molecule in space. This
has sweeping implications in biological systems. For example, most drugs are often
composed of a single stereoisomer of a compound. Among stereoisomers one may have
positive effects on the body and another stereoisomer may not or could even be toxic. An
example of this is the drug thalidomide which was used during the 1950s to suppress the
morning sickness. The drug unfortunately, was prescribed as a mixture of stereoisomers, and
while one stereoisomer actively worked on controlling morning sickness, the other
stereoisomer caused serious birth defects.
The study of stereochemistry focuses on stereoisomers and spans the entire spectrum of
organic, inorganic, biological, physical and especially supramolecular chemistry.
Stereochemistry includes method for determining and describing these relationships; the
effect on the physical or biological properties.
, So to have the sound knowledge of stereochemistry we should have good command over their
basic concepts.
1.2. OBJECTIVES:
• Classification of stereoisomers
• Recognize a stereogenic (chiral) center in a molecular structure
• Various representation of three dimentional molecules
• To be able to predict, identify and distinguish between enantiomers and diastereomers.
• Various nomenclature of stereoisomers to define them properly
1.3. STEREOCHEMISTRY: DEFINITION
The branch of chemistry which deals with three dimensional structure of molecule and their
effect on physical and chemical properties is known as stereochemistry. To represent
molecule as three dimensional object we need at least one carbon sp3- hybridized.
Example:
H
Cl
2D drawing Not appropriate for steriochemistry
I Br
H
3D drawing appropriate for steriochemistry
Cl
I Br
