This chapter provides a thorough exploration of the stereochemistry of organic
compounds, a fundamental aspect of organic chemistry that influences the physical and chemical
properties of molecules. The chapter begins with isomerism, distinguishing between the different
types of isomers and setting the stage for a deeper investigation into structural isomerism and
stereoisomerism.
Structural isomerism is examined, focusing on isomers that differ in the connectivity of their atoms,
affecting their chemical behavior and properties. Stereoisomerism, which includes isomers with the
same connectivity but different spatial arrangements, is introduced as a key concept in understanding
molecular diversity.
Optical isomerism is detailed, highlighting the role of chirality and the ability of certain molecules
to rotate plane-polarized light. The concept of chirality is expanded upon, discussing chiral centers
and the absence of elements of symmetry, which leads to the existence of non-superimposable mirror
images.
Enantiomerism, the relationship between pairs of chiral molecules that are mirror images of each
other, is explored, emphasizing its significance in biological systems and pharmaceuticals.
Projection formulas, including Fischer and Newman projections, are introduced as tools to represent
three-dimensional structures in two dimensions, aiding in the visualization and differentiation of
isomers. Diastereomers, stereoisomers that are not mirror images, are discussed with a focus on their
different physical and chemical properties compared to enantiomers. The concept of prochirality is
introduced, explaining how certain molecules can become chiral through specific chemical
modifications.
Resolution techniques for separating racemic mixtures into individual enantiomers are covered,
highlighting methods such as chiral chromatography and enzymatic resolution. Racemic mixtures,
equimolar mixtures of enantiomers, are examined in terms of their formation and the challenges
they present in synthesis and analysis.
This chapter equips readers with a comprehensive understanding of stereochemistry, providing the
knowledge necessary to predict and explain the behavior of organic compounds based on their threedimensional structures, essential for advanced studies and practical applications in organic
chemistry.
Keywords: Chirality; Diastereomers; Elements of symmetry; Enantiomerism; Isomerism; Optical isomerism; Projection formulas; Prochirality; Resolution; Racemic mixtures; Structural isomerism; Stereoisomerism.
